1//===-- AddressSanitizer.cpp - memory error detector ------------*- C++ -*-===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9//
10// This file is a part of AddressSanitizer, an address sanity checker.
11// Details of the algorithm:
12//  http://code.google.com/p/address-sanitizer/wiki/AddressSanitizerAlgorithm
13//
14//===----------------------------------------------------------------------===//
15
16#include "llvm/Transforms/Instrumentation.h"
17#include "llvm/ADT/ArrayRef.h"
18#include "llvm/ADT/DenseMap.h"
19#include "llvm/ADT/DenseSet.h"
20#include "llvm/ADT/DepthFirstIterator.h"
21#include "llvm/ADT/SmallSet.h"
22#include "llvm/ADT/SmallString.h"
23#include "llvm/ADT/SmallVector.h"
24#include "llvm/ADT/Statistic.h"
25#include "llvm/ADT/StringExtras.h"
26#include "llvm/ADT/Triple.h"
27#include "llvm/Analysis/MemoryBuiltins.h"
28#include "llvm/Analysis/TargetLibraryInfo.h"
29#include "llvm/Analysis/ValueTracking.h"
30#include "llvm/IR/CallSite.h"
31#include "llvm/IR/DIBuilder.h"
32#include "llvm/IR/DataLayout.h"
33#include "llvm/IR/Dominators.h"
34#include "llvm/IR/Function.h"
35#include "llvm/IR/IRBuilder.h"
36#include "llvm/IR/InlineAsm.h"
37#include "llvm/IR/InstVisitor.h"
38#include "llvm/IR/IntrinsicInst.h"
39#include "llvm/IR/LLVMContext.h"
40#include "llvm/IR/MDBuilder.h"
41#include "llvm/IR/Module.h"
42#include "llvm/IR/Type.h"
43#include "llvm/MC/MCSectionMachO.h"
44#include "llvm/Support/CommandLine.h"
45#include "llvm/Support/DataTypes.h"
46#include "llvm/Support/Debug.h"
47#include "llvm/Support/Endian.h"
48#include "llvm/Support/SwapByteOrder.h"
49#include "llvm/Support/raw_ostream.h"
50#include "llvm/Transforms/Scalar.h"
51#include "llvm/Transforms/Utils/ASanStackFrameLayout.h"
52#include "llvm/Transforms/Utils/BasicBlockUtils.h"
53#include "llvm/Transforms/Utils/Cloning.h"
54#include "llvm/Transforms/Utils/Local.h"
55#include "llvm/Transforms/Utils/ModuleUtils.h"
56#include "llvm/Transforms/Utils/PromoteMemToReg.h"
57#include <algorithm>
58#include <string>
59#include <system_error>
60
61using namespace llvm;
62
63#define DEBUG_TYPE "asan"
64
65static const uint64_t kDefaultShadowScale = 3;
66static const uint64_t kDefaultShadowOffset32 = 1ULL << 29;
67static const uint64_t kIOSShadowOffset32 = 1ULL << 30;
68static const uint64_t kDefaultShadowOffset64 = 1ULL << 44;
69static const uint64_t kSmallX86_64ShadowOffset = 0x7FFF8000;  // < 2G.
70static const uint64_t kPPC64_ShadowOffset64 = 1ULL << 41;
71static const uint64_t kMIPS32_ShadowOffset32 = 0x0aaa0000;
72static const uint64_t kMIPS64_ShadowOffset64 = 1ULL << 37;
73static const uint64_t kAArch64_ShadowOffset64 = 1ULL << 36;
74static const uint64_t kFreeBSD_ShadowOffset32 = 1ULL << 30;
75static const uint64_t kFreeBSD_ShadowOffset64 = 1ULL << 46;
76static const uint64_t kWindowsShadowOffset32 = 3ULL << 28;
77
78static const size_t kMinStackMallocSize = 1 << 6;   // 64B
79static const size_t kMaxStackMallocSize = 1 << 16;  // 64K
80static const uintptr_t kCurrentStackFrameMagic = 0x41B58AB3;
81static const uintptr_t kRetiredStackFrameMagic = 0x45E0360E;
82
83static const char *const kAsanModuleCtorName = "asan.module_ctor";
84static const char *const kAsanModuleDtorName = "asan.module_dtor";
85static const uint64_t kAsanCtorAndDtorPriority = 1;
86static const char *const kAsanReportErrorTemplate = "__asan_report_";
87static const char *const kAsanRegisterGlobalsName = "__asan_register_globals";
88static const char *const kAsanUnregisterGlobalsName =
89    "__asan_unregister_globals";
90static const char *const kAsanPoisonGlobalsName = "__asan_before_dynamic_init";
91static const char *const kAsanUnpoisonGlobalsName = "__asan_after_dynamic_init";
92static const char *const kAsanInitName = "__asan_init_v5";
93static const char *const kAsanPtrCmp = "__sanitizer_ptr_cmp";
94static const char *const kAsanPtrSub = "__sanitizer_ptr_sub";
95static const char *const kAsanHandleNoReturnName = "__asan_handle_no_return";
96static const int kMaxAsanStackMallocSizeClass = 10;
97static const char *const kAsanStackMallocNameTemplate = "__asan_stack_malloc_";
98static const char *const kAsanStackFreeNameTemplate = "__asan_stack_free_";
99static const char *const kAsanGenPrefix = "__asan_gen_";
100static const char *const kSanCovGenPrefix = "__sancov_gen_";
101static const char *const kAsanPoisonStackMemoryName =
102    "__asan_poison_stack_memory";
103static const char *const kAsanUnpoisonStackMemoryName =
104    "__asan_unpoison_stack_memory";
105
106static const char *const kAsanOptionDetectUAR =
107    "__asan_option_detect_stack_use_after_return";
108
109// Accesses sizes are powers of two: 1, 2, 4, 8, 16.
110static const size_t kNumberOfAccessSizes = 5;
111
112static const unsigned kAllocaRzSize = 32;
113static const unsigned kAsanAllocaLeftMagic = 0xcacacacaU;
114static const unsigned kAsanAllocaRightMagic = 0xcbcbcbcbU;
115static const unsigned kAsanAllocaPartialVal1 = 0xcbcbcb00U;
116static const unsigned kAsanAllocaPartialVal2 = 0x000000cbU;
117
118// Command-line flags.
119
120// This flag may need to be replaced with -f[no-]asan-reads.
121static cl::opt<bool> ClInstrumentReads("asan-instrument-reads",
122                                       cl::desc("instrument read instructions"),
123                                       cl::Hidden, cl::init(true));
124static cl::opt<bool> ClInstrumentWrites(
125    "asan-instrument-writes", cl::desc("instrument write instructions"),
126    cl::Hidden, cl::init(true));
127static cl::opt<bool> ClInstrumentAtomics(
128    "asan-instrument-atomics",
129    cl::desc("instrument atomic instructions (rmw, cmpxchg)"), cl::Hidden,
130    cl::init(true));
131static cl::opt<bool> ClAlwaysSlowPath(
132    "asan-always-slow-path",
133    cl::desc("use instrumentation with slow path for all accesses"), cl::Hidden,
134    cl::init(false));
135// This flag limits the number of instructions to be instrumented
136// in any given BB. Normally, this should be set to unlimited (INT_MAX),
137// but due to http://llvm.org/bugs/show_bug.cgi?id=12652 we temporary
138// set it to 10000.
139static cl::opt<int> ClMaxInsnsToInstrumentPerBB(
140    "asan-max-ins-per-bb", cl::init(10000),
141    cl::desc("maximal number of instructions to instrument in any given BB"),
142    cl::Hidden);
143// This flag may need to be replaced with -f[no]asan-stack.
144static cl::opt<bool> ClStack("asan-stack", cl::desc("Handle stack memory"),
145                             cl::Hidden, cl::init(true));
146static cl::opt<bool> ClUseAfterReturn("asan-use-after-return",
147                                      cl::desc("Check return-after-free"),
148                                      cl::Hidden, cl::init(true));
149// This flag may need to be replaced with -f[no]asan-globals.
150static cl::opt<bool> ClGlobals("asan-globals",
151                               cl::desc("Handle global objects"), cl::Hidden,
152                               cl::init(true));
153static cl::opt<bool> ClInitializers("asan-initialization-order",
154                                    cl::desc("Handle C++ initializer order"),
155                                    cl::Hidden, cl::init(true));
156static cl::opt<bool> ClInvalidPointerPairs(
157    "asan-detect-invalid-pointer-pair",
158    cl::desc("Instrument <, <=, >, >=, - with pointer operands"), cl::Hidden,
159    cl::init(false));
160static cl::opt<unsigned> ClRealignStack(
161    "asan-realign-stack",
162    cl::desc("Realign stack to the value of this flag (power of two)"),
163    cl::Hidden, cl::init(32));
164static cl::opt<int> ClInstrumentationWithCallsThreshold(
165    "asan-instrumentation-with-call-threshold",
166    cl::desc(
167        "If the function being instrumented contains more than "
168        "this number of memory accesses, use callbacks instead of "
169        "inline checks (-1 means never use callbacks)."),
170    cl::Hidden, cl::init(7000));
171static cl::opt<std::string> ClMemoryAccessCallbackPrefix(
172    "asan-memory-access-callback-prefix",
173    cl::desc("Prefix for memory access callbacks"), cl::Hidden,
174    cl::init("__asan_"));
175static cl::opt<bool> ClInstrumentAllocas("asan-instrument-allocas",
176                                         cl::desc("instrument dynamic allocas"),
177                                         cl::Hidden, cl::init(false));
178static cl::opt<bool> ClSkipPromotableAllocas(
179    "asan-skip-promotable-allocas",
180    cl::desc("Do not instrument promotable allocas"), cl::Hidden,
181    cl::init(true));
182
183// These flags allow to change the shadow mapping.
184// The shadow mapping looks like
185//    Shadow = (Mem >> scale) + (1 << offset_log)
186static cl::opt<int> ClMappingScale("asan-mapping-scale",
187                                   cl::desc("scale of asan shadow mapping"),
188                                   cl::Hidden, cl::init(0));
189
190// Optimization flags. Not user visible, used mostly for testing
191// and benchmarking the tool.
192static cl::opt<bool> ClOpt("asan-opt", cl::desc("Optimize instrumentation"),
193                           cl::Hidden, cl::init(true));
194static cl::opt<bool> ClOptSameTemp(
195    "asan-opt-same-temp", cl::desc("Instrument the same temp just once"),
196    cl::Hidden, cl::init(true));
197static cl::opt<bool> ClOptGlobals("asan-opt-globals",
198                                  cl::desc("Don't instrument scalar globals"),
199                                  cl::Hidden, cl::init(true));
200static cl::opt<bool> ClOptStack(
201    "asan-opt-stack", cl::desc("Don't instrument scalar stack variables"),
202    cl::Hidden, cl::init(false));
203
204static cl::opt<bool> ClCheckLifetime(
205    "asan-check-lifetime",
206    cl::desc("Use llvm.lifetime intrinsics to insert extra checks"), cl::Hidden,
207    cl::init(false));
208
209static cl::opt<bool> ClDynamicAllocaStack(
210    "asan-stack-dynamic-alloca",
211    cl::desc("Use dynamic alloca to represent stack variables"), cl::Hidden,
212    cl::init(true));
213
214static cl::opt<uint32_t> ClForceExperiment(
215    "asan-force-experiment",
216    cl::desc("Force optimization experiment (for testing)"), cl::Hidden,
217    cl::init(0));
218
219// Debug flags.
220static cl::opt<int> ClDebug("asan-debug", cl::desc("debug"), cl::Hidden,
221                            cl::init(0));
222static cl::opt<int> ClDebugStack("asan-debug-stack", cl::desc("debug stack"),
223                                 cl::Hidden, cl::init(0));
224static cl::opt<std::string> ClDebugFunc("asan-debug-func", cl::Hidden,
225                                        cl::desc("Debug func"));
226static cl::opt<int> ClDebugMin("asan-debug-min", cl::desc("Debug min inst"),
227                               cl::Hidden, cl::init(-1));
228static cl::opt<int> ClDebugMax("asan-debug-max", cl::desc("Debug man inst"),
229                               cl::Hidden, cl::init(-1));
230
231STATISTIC(NumInstrumentedReads, "Number of instrumented reads");
232STATISTIC(NumInstrumentedWrites, "Number of instrumented writes");
233STATISTIC(NumInstrumentedDynamicAllocas,
234          "Number of instrumented dynamic allocas");
235STATISTIC(NumOptimizedAccessesToGlobalVar,
236          "Number of optimized accesses to global vars");
237STATISTIC(NumOptimizedAccessesToStackVar,
238          "Number of optimized accesses to stack vars");
239
240namespace {
241/// Frontend-provided metadata for source location.
242struct LocationMetadata {
243  StringRef Filename;
244  int LineNo;
245  int ColumnNo;
246
247  LocationMetadata() : Filename(), LineNo(0), ColumnNo(0) {}
248
249  bool empty() const { return Filename.empty(); }
250
251  void parse(MDNode *MDN) {
252    assert(MDN->getNumOperands() == 3);
253    MDString *MDFilename = cast<MDString>(MDN->getOperand(0));
254    Filename = MDFilename->getString();
255    LineNo =
256        mdconst::extract<ConstantInt>(MDN->getOperand(1))->getLimitedValue();
257    ColumnNo =
258        mdconst::extract<ConstantInt>(MDN->getOperand(2))->getLimitedValue();
259  }
260};
261
262/// Frontend-provided metadata for global variables.
263class GlobalsMetadata {
264 public:
265  struct Entry {
266    Entry() : SourceLoc(), Name(), IsDynInit(false), IsBlacklisted(false) {}
267    LocationMetadata SourceLoc;
268    StringRef Name;
269    bool IsDynInit;
270    bool IsBlacklisted;
271  };
272
273  GlobalsMetadata() : inited_(false) {}
274
275  void init(Module &M) {
276    assert(!inited_);
277    inited_ = true;
278    NamedMDNode *Globals = M.getNamedMetadata("llvm.asan.globals");
279    if (!Globals) return;
280    for (auto MDN : Globals->operands()) {
281      // Metadata node contains the global and the fields of "Entry".
282      assert(MDN->getNumOperands() == 5);
283      auto *GV = mdconst::extract_or_null<GlobalVariable>(MDN->getOperand(0));
284      // The optimizer may optimize away a global entirely.
285      if (!GV) continue;
286      // We can already have an entry for GV if it was merged with another
287      // global.
288      Entry &E = Entries[GV];
289      if (auto *Loc = cast_or_null<MDNode>(MDN->getOperand(1)))
290        E.SourceLoc.parse(Loc);
291      if (auto *Name = cast_or_null<MDString>(MDN->getOperand(2)))
292        E.Name = Name->getString();
293      ConstantInt *IsDynInit =
294          mdconst::extract<ConstantInt>(MDN->getOperand(3));
295      E.IsDynInit |= IsDynInit->isOne();
296      ConstantInt *IsBlacklisted =
297          mdconst::extract<ConstantInt>(MDN->getOperand(4));
298      E.IsBlacklisted |= IsBlacklisted->isOne();
299    }
300  }
301
302  /// Returns metadata entry for a given global.
303  Entry get(GlobalVariable *G) const {
304    auto Pos = Entries.find(G);
305    return (Pos != Entries.end()) ? Pos->second : Entry();
306  }
307
308 private:
309  bool inited_;
310  DenseMap<GlobalVariable *, Entry> Entries;
311};
312
313/// This struct defines the shadow mapping using the rule:
314///   shadow = (mem >> Scale) ADD-or-OR Offset.
315struct ShadowMapping {
316  int Scale;
317  uint64_t Offset;
318  bool OrShadowOffset;
319};
320
321static ShadowMapping getShadowMapping(Triple &TargetTriple, int LongSize) {
322  bool IsAndroid = TargetTriple.getEnvironment() == llvm::Triple::Android;
323  bool IsIOS = TargetTriple.isiOS();
324  bool IsFreeBSD = TargetTriple.isOSFreeBSD();
325  bool IsLinux = TargetTriple.isOSLinux();
326  bool IsPPC64 = TargetTriple.getArch() == llvm::Triple::ppc64 ||
327                 TargetTriple.getArch() == llvm::Triple::ppc64le;
328  bool IsX86_64 = TargetTriple.getArch() == llvm::Triple::x86_64;
329  bool IsMIPS32 = TargetTriple.getArch() == llvm::Triple::mips ||
330                  TargetTriple.getArch() == llvm::Triple::mipsel;
331  bool IsMIPS64 = TargetTriple.getArch() == llvm::Triple::mips64 ||
332                  TargetTriple.getArch() == llvm::Triple::mips64el;
333  bool IsAArch64 = TargetTriple.getArch() == llvm::Triple::aarch64;
334  bool IsWindows = TargetTriple.isOSWindows();
335
336  ShadowMapping Mapping;
337
338  if (LongSize == 32) {
339    if (IsAndroid)
340      Mapping.Offset = 0;
341    else if (IsMIPS32)
342      Mapping.Offset = kMIPS32_ShadowOffset32;
343    else if (IsFreeBSD)
344      Mapping.Offset = kFreeBSD_ShadowOffset32;
345    else if (IsIOS)
346      Mapping.Offset = kIOSShadowOffset32;
347    else if (IsWindows)
348      Mapping.Offset = kWindowsShadowOffset32;
349    else
350      Mapping.Offset = kDefaultShadowOffset32;
351  } else {  // LongSize == 64
352    if (IsPPC64)
353      Mapping.Offset = kPPC64_ShadowOffset64;
354    else if (IsFreeBSD)
355      Mapping.Offset = kFreeBSD_ShadowOffset64;
356    else if (IsLinux && IsX86_64)
357      Mapping.Offset = kSmallX86_64ShadowOffset;
358    else if (IsMIPS64)
359      Mapping.Offset = kMIPS64_ShadowOffset64;
360    else if (IsAArch64)
361      Mapping.Offset = kAArch64_ShadowOffset64;
362    else
363      Mapping.Offset = kDefaultShadowOffset64;
364  }
365
366  Mapping.Scale = kDefaultShadowScale;
367  if (ClMappingScale) {
368    Mapping.Scale = ClMappingScale;
369  }
370
371  // OR-ing shadow offset if more efficient (at least on x86) if the offset
372  // is a power of two, but on ppc64 we have to use add since the shadow
373  // offset is not necessary 1/8-th of the address space.
374  Mapping.OrShadowOffset = !IsPPC64 && !(Mapping.Offset & (Mapping.Offset - 1));
375
376  return Mapping;
377}
378
379static size_t RedzoneSizeForScale(int MappingScale) {
380  // Redzone used for stack and globals is at least 32 bytes.
381  // For scales 6 and 7, the redzone has to be 64 and 128 bytes respectively.
382  return std::max(32U, 1U << MappingScale);
383}
384
385/// AddressSanitizer: instrument the code in module to find memory bugs.
386struct AddressSanitizer : public FunctionPass {
387  AddressSanitizer() : FunctionPass(ID) {
388    initializeAddressSanitizerPass(*PassRegistry::getPassRegistry());
389  }
390  const char *getPassName() const override {
391    return "AddressSanitizerFunctionPass";
392  }
393  void getAnalysisUsage(AnalysisUsage &AU) const override {
394    AU.addRequired<DominatorTreeWrapperPass>();
395    AU.addRequired<TargetLibraryInfoWrapperPass>();
396  }
397  uint64_t getAllocaSizeInBytes(AllocaInst *AI) const {
398    Type *Ty = AI->getAllocatedType();
399    uint64_t SizeInBytes =
400        AI->getModule()->getDataLayout().getTypeAllocSize(Ty);
401    return SizeInBytes;
402  }
403  /// Check if we want (and can) handle this alloca.
404  bool isInterestingAlloca(AllocaInst &AI);
405  /// If it is an interesting memory access, return the PointerOperand
406  /// and set IsWrite/Alignment. Otherwise return nullptr.
407  Value *isInterestingMemoryAccess(Instruction *I, bool *IsWrite,
408                                   uint64_t *TypeSize,
409                                   unsigned *Alignment);
410  void instrumentMop(ObjectSizeOffsetVisitor &ObjSizeVis, Instruction *I,
411                     bool UseCalls, const DataLayout &DL);
412  void instrumentPointerComparisonOrSubtraction(Instruction *I);
413  void instrumentAddress(Instruction *OrigIns, Instruction *InsertBefore,
414                         Value *Addr, uint32_t TypeSize, bool IsWrite,
415                         Value *SizeArgument, bool UseCalls, uint32_t Exp);
416  void instrumentUnusualSizeOrAlignment(Instruction *I, Value *Addr,
417                                        uint32_t TypeSize, bool IsWrite,
418                                        Value *SizeArgument, bool UseCalls,
419                                        uint32_t Exp);
420  Value *createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
421                           Value *ShadowValue, uint32_t TypeSize);
422  Instruction *generateCrashCode(Instruction *InsertBefore, Value *Addr,
423                                 bool IsWrite, size_t AccessSizeIndex,
424                                 Value *SizeArgument, uint32_t Exp);
425  void instrumentMemIntrinsic(MemIntrinsic *MI);
426  Value *memToShadow(Value *Shadow, IRBuilder<> &IRB);
427  bool runOnFunction(Function &F) override;
428  bool maybeInsertAsanInitAtFunctionEntry(Function &F);
429  bool doInitialization(Module &M) override;
430  static char ID;  // Pass identification, replacement for typeid
431
432  DominatorTree &getDominatorTree() const { return *DT; }
433
434 private:
435  void initializeCallbacks(Module &M);
436
437  bool LooksLikeCodeInBug11395(Instruction *I);
438  bool GlobalIsLinkerInitialized(GlobalVariable *G);
439  bool isSafeAccess(ObjectSizeOffsetVisitor &ObjSizeVis, Value *Addr,
440                    uint64_t TypeSize) const;
441
442  LLVMContext *C;
443  Triple TargetTriple;
444  int LongSize;
445  Type *IntptrTy;
446  ShadowMapping Mapping;
447  DominatorTree *DT;
448  Function *AsanCtorFunction;
449  Function *AsanInitFunction;
450  Function *AsanHandleNoReturnFunc;
451  Function *AsanPtrCmpFunction, *AsanPtrSubFunction;
452  // This array is indexed by AccessIsWrite, Experiment and log2(AccessSize).
453  Function *AsanErrorCallback[2][2][kNumberOfAccessSizes];
454  Function *AsanMemoryAccessCallback[2][2][kNumberOfAccessSizes];
455  // This array is indexed by AccessIsWrite and Experiment.
456  Function *AsanErrorCallbackSized[2][2];
457  Function *AsanMemoryAccessCallbackSized[2][2];
458  Function *AsanMemmove, *AsanMemcpy, *AsanMemset;
459  InlineAsm *EmptyAsm;
460  GlobalsMetadata GlobalsMD;
461  DenseMap<AllocaInst *, bool> ProcessedAllocas;
462
463  friend struct FunctionStackPoisoner;
464};
465
466class AddressSanitizerModule : public ModulePass {
467 public:
468  AddressSanitizerModule() : ModulePass(ID) {}
469  bool runOnModule(Module &M) override;
470  static char ID;  // Pass identification, replacement for typeid
471  const char *getPassName() const override { return "AddressSanitizerModule"; }
472
473 private:
474  void initializeCallbacks(Module &M);
475
476  bool InstrumentGlobals(IRBuilder<> &IRB, Module &M);
477  bool ShouldInstrumentGlobal(GlobalVariable *G);
478  void poisonOneInitializer(Function &GlobalInit, GlobalValue *ModuleName);
479  void createInitializerPoisonCalls(Module &M, GlobalValue *ModuleName);
480  size_t MinRedzoneSizeForGlobal() const {
481    return RedzoneSizeForScale(Mapping.Scale);
482  }
483
484  GlobalsMetadata GlobalsMD;
485  Type *IntptrTy;
486  LLVMContext *C;
487  Triple TargetTriple;
488  ShadowMapping Mapping;
489  Function *AsanPoisonGlobals;
490  Function *AsanUnpoisonGlobals;
491  Function *AsanRegisterGlobals;
492  Function *AsanUnregisterGlobals;
493};
494
495// Stack poisoning does not play well with exception handling.
496// When an exception is thrown, we essentially bypass the code
497// that unpoisones the stack. This is why the run-time library has
498// to intercept __cxa_throw (as well as longjmp, etc) and unpoison the entire
499// stack in the interceptor. This however does not work inside the
500// actual function which catches the exception. Most likely because the
501// compiler hoists the load of the shadow value somewhere too high.
502// This causes asan to report a non-existing bug on 453.povray.
503// It sounds like an LLVM bug.
504struct FunctionStackPoisoner : public InstVisitor<FunctionStackPoisoner> {
505  Function &F;
506  AddressSanitizer &ASan;
507  DIBuilder DIB;
508  LLVMContext *C;
509  Type *IntptrTy;
510  Type *IntptrPtrTy;
511  ShadowMapping Mapping;
512
513  SmallVector<AllocaInst *, 16> AllocaVec;
514  SmallVector<Instruction *, 8> RetVec;
515  unsigned StackAlignment;
516
517  Function *AsanStackMallocFunc[kMaxAsanStackMallocSizeClass + 1],
518      *AsanStackFreeFunc[kMaxAsanStackMallocSizeClass + 1];
519  Function *AsanPoisonStackMemoryFunc, *AsanUnpoisonStackMemoryFunc;
520
521  // Stores a place and arguments of poisoning/unpoisoning call for alloca.
522  struct AllocaPoisonCall {
523    IntrinsicInst *InsBefore;
524    AllocaInst *AI;
525    uint64_t Size;
526    bool DoPoison;
527  };
528  SmallVector<AllocaPoisonCall, 8> AllocaPoisonCallVec;
529
530  // Stores left and right redzone shadow addresses for dynamic alloca
531  // and pointer to alloca instruction itself.
532  // LeftRzAddr is a shadow address for alloca left redzone.
533  // RightRzAddr is a shadow address for alloca right redzone.
534  struct DynamicAllocaCall {
535    AllocaInst *AI;
536    Value *LeftRzAddr;
537    Value *RightRzAddr;
538    bool Poison;
539    explicit DynamicAllocaCall(AllocaInst *AI, Value *LeftRzAddr = nullptr,
540                               Value *RightRzAddr = nullptr)
541        : AI(AI),
542          LeftRzAddr(LeftRzAddr),
543          RightRzAddr(RightRzAddr),
544          Poison(true) {}
545  };
546  SmallVector<DynamicAllocaCall, 1> DynamicAllocaVec;
547
548  // Maps Value to an AllocaInst from which the Value is originated.
549  typedef DenseMap<Value *, AllocaInst *> AllocaForValueMapTy;
550  AllocaForValueMapTy AllocaForValue;
551
552  bool HasNonEmptyInlineAsm;
553  std::unique_ptr<CallInst> EmptyInlineAsm;
554
555  FunctionStackPoisoner(Function &F, AddressSanitizer &ASan)
556      : F(F),
557        ASan(ASan),
558        DIB(*F.getParent(), /*AllowUnresolved*/ false),
559        C(ASan.C),
560        IntptrTy(ASan.IntptrTy),
561        IntptrPtrTy(PointerType::get(IntptrTy, 0)),
562        Mapping(ASan.Mapping),
563        StackAlignment(1 << Mapping.Scale),
564        HasNonEmptyInlineAsm(false),
565        EmptyInlineAsm(CallInst::Create(ASan.EmptyAsm)) {}
566
567  bool runOnFunction() {
568    if (!ClStack) return false;
569    // Collect alloca, ret, lifetime instructions etc.
570    for (BasicBlock *BB : depth_first(&F.getEntryBlock())) visit(*BB);
571
572    if (AllocaVec.empty() && DynamicAllocaVec.empty()) return false;
573
574    initializeCallbacks(*F.getParent());
575
576    poisonStack();
577
578    if (ClDebugStack) {
579      DEBUG(dbgs() << F);
580    }
581    return true;
582  }
583
584  // Finds all Alloca instructions and puts
585  // poisoned red zones around all of them.
586  // Then unpoison everything back before the function returns.
587  void poisonStack();
588
589  // ----------------------- Visitors.
590  /// \brief Collect all Ret instructions.
591  void visitReturnInst(ReturnInst &RI) { RetVec.push_back(&RI); }
592
593  // Unpoison dynamic allocas redzones.
594  void unpoisonDynamicAlloca(DynamicAllocaCall &AllocaCall) {
595    if (!AllocaCall.Poison) return;
596    for (auto Ret : RetVec) {
597      IRBuilder<> IRBRet(Ret);
598      PointerType *Int32PtrTy = PointerType::getUnqual(IRBRet.getInt32Ty());
599      Value *Zero = Constant::getNullValue(IRBRet.getInt32Ty());
600      Value *PartialRzAddr = IRBRet.CreateSub(AllocaCall.RightRzAddr,
601                                              ConstantInt::get(IntptrTy, 4));
602      IRBRet.CreateStore(
603          Zero, IRBRet.CreateIntToPtr(AllocaCall.LeftRzAddr, Int32PtrTy));
604      IRBRet.CreateStore(Zero,
605                         IRBRet.CreateIntToPtr(PartialRzAddr, Int32PtrTy));
606      IRBRet.CreateStore(
607          Zero, IRBRet.CreateIntToPtr(AllocaCall.RightRzAddr, Int32PtrTy));
608    }
609  }
610
611  // Right shift for BigEndian and left shift for LittleEndian.
612  Value *shiftAllocaMagic(Value *Val, IRBuilder<> &IRB, Value *Shift) {
613    auto &DL = F.getParent()->getDataLayout();
614    return DL.isLittleEndian() ? IRB.CreateShl(Val, Shift)
615                               : IRB.CreateLShr(Val, Shift);
616  }
617
618  // Compute PartialRzMagic for dynamic alloca call. Since we don't know the
619  // size of requested memory until runtime, we should compute it dynamically.
620  // If PartialSize is 0, PartialRzMagic would contain kAsanAllocaRightMagic,
621  // otherwise it would contain the value that we will use to poison the
622  // partial redzone for alloca call.
623  Value *computePartialRzMagic(Value *PartialSize, IRBuilder<> &IRB);
624
625  // Deploy and poison redzones around dynamic alloca call. To do this, we
626  // should replace this call with another one with changed parameters and
627  // replace all its uses with new address, so
628  //   addr = alloca type, old_size, align
629  // is replaced by
630  //   new_size = (old_size + additional_size) * sizeof(type)
631  //   tmp = alloca i8, new_size, max(align, 32)
632  //   addr = tmp + 32 (first 32 bytes are for the left redzone).
633  // Additional_size is added to make new memory allocation contain not only
634  // requested memory, but also left, partial and right redzones.
635  // After that, we should poison redzones:
636  // (1) Left redzone with kAsanAllocaLeftMagic.
637  // (2) Partial redzone with the value, computed in runtime by
638  //     computePartialRzMagic function.
639  // (3) Right redzone with kAsanAllocaRightMagic.
640  void handleDynamicAllocaCall(DynamicAllocaCall &AllocaCall);
641
642  /// \brief Collect Alloca instructions we want (and can) handle.
643  void visitAllocaInst(AllocaInst &AI) {
644    if (!ASan.isInterestingAlloca(AI)) return;
645
646    StackAlignment = std::max(StackAlignment, AI.getAlignment());
647    if (isDynamicAlloca(AI))
648      DynamicAllocaVec.push_back(DynamicAllocaCall(&AI));
649    else
650      AllocaVec.push_back(&AI);
651  }
652
653  /// \brief Collect lifetime intrinsic calls to check for use-after-scope
654  /// errors.
655  void visitIntrinsicInst(IntrinsicInst &II) {
656    if (!ClCheckLifetime) return;
657    Intrinsic::ID ID = II.getIntrinsicID();
658    if (ID != Intrinsic::lifetime_start && ID != Intrinsic::lifetime_end)
659      return;
660    // Found lifetime intrinsic, add ASan instrumentation if necessary.
661    ConstantInt *Size = dyn_cast<ConstantInt>(II.getArgOperand(0));
662    // If size argument is undefined, don't do anything.
663    if (Size->isMinusOne()) return;
664    // Check that size doesn't saturate uint64_t and can
665    // be stored in IntptrTy.
666    const uint64_t SizeValue = Size->getValue().getLimitedValue();
667    if (SizeValue == ~0ULL ||
668        !ConstantInt::isValueValidForType(IntptrTy, SizeValue))
669      return;
670    // Find alloca instruction that corresponds to llvm.lifetime argument.
671    AllocaInst *AI = findAllocaForValue(II.getArgOperand(1));
672    if (!AI) return;
673    bool DoPoison = (ID == Intrinsic::lifetime_end);
674    AllocaPoisonCall APC = {&II, AI, SizeValue, DoPoison};
675    AllocaPoisonCallVec.push_back(APC);
676  }
677
678  void visitCallInst(CallInst &CI) {
679    HasNonEmptyInlineAsm |=
680        CI.isInlineAsm() && !CI.isIdenticalTo(EmptyInlineAsm.get());
681  }
682
683  // ---------------------- Helpers.
684  void initializeCallbacks(Module &M);
685
686  bool doesDominateAllExits(const Instruction *I) const {
687    for (auto Ret : RetVec) {
688      if (!ASan.getDominatorTree().dominates(I, Ret)) return false;
689    }
690    return true;
691  }
692
693  bool isDynamicAlloca(AllocaInst &AI) const {
694    return AI.isArrayAllocation() || !AI.isStaticAlloca();
695  }
696  /// Finds alloca where the value comes from.
697  AllocaInst *findAllocaForValue(Value *V);
698  void poisonRedZones(ArrayRef<uint8_t> ShadowBytes, IRBuilder<> &IRB,
699                      Value *ShadowBase, bool DoPoison);
700  void poisonAlloca(Value *V, uint64_t Size, IRBuilder<> &IRB, bool DoPoison);
701
702  void SetShadowToStackAfterReturnInlined(IRBuilder<> &IRB, Value *ShadowBase,
703                                          int Size);
704  Value *createAllocaForLayout(IRBuilder<> &IRB, const ASanStackFrameLayout &L,
705                               bool Dynamic);
706  PHINode *createPHI(IRBuilder<> &IRB, Value *Cond, Value *ValueIfTrue,
707                     Instruction *ThenTerm, Value *ValueIfFalse);
708};
709
710}  // namespace
711
712char AddressSanitizer::ID = 0;
713INITIALIZE_PASS_BEGIN(
714    AddressSanitizer, "asan",
715    "AddressSanitizer: detects use-after-free and out-of-bounds bugs.", false,
716    false)
717INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)
718INITIALIZE_PASS_END(
719    AddressSanitizer, "asan",
720    "AddressSanitizer: detects use-after-free and out-of-bounds bugs.", false,
721    false)
722FunctionPass *llvm::createAddressSanitizerFunctionPass() {
723  return new AddressSanitizer();
724}
725
726char AddressSanitizerModule::ID = 0;
727INITIALIZE_PASS(
728    AddressSanitizerModule, "asan-module",
729    "AddressSanitizer: detects use-after-free and out-of-bounds bugs."
730    "ModulePass",
731    false, false)
732ModulePass *llvm::createAddressSanitizerModulePass() {
733  return new AddressSanitizerModule();
734}
735
736static size_t TypeSizeToSizeIndex(uint32_t TypeSize) {
737  size_t Res = countTrailingZeros(TypeSize / 8);
738  assert(Res < kNumberOfAccessSizes);
739  return Res;
740}
741
742// \brief Create a constant for Str so that we can pass it to the run-time lib.
743static GlobalVariable *createPrivateGlobalForString(Module &M, StringRef Str,
744                                                    bool AllowMerging) {
745  Constant *StrConst = ConstantDataArray::getString(M.getContext(), Str);
746  // We use private linkage for module-local strings. If they can be merged
747  // with another one, we set the unnamed_addr attribute.
748  GlobalVariable *GV =
749      new GlobalVariable(M, StrConst->getType(), true,
750                         GlobalValue::PrivateLinkage, StrConst, kAsanGenPrefix);
751  if (AllowMerging) GV->setUnnamedAddr(true);
752  GV->setAlignment(1);  // Strings may not be merged w/o setting align 1.
753  return GV;
754}
755
756/// \brief Create a global describing a source location.
757static GlobalVariable *createPrivateGlobalForSourceLoc(Module &M,
758                                                       LocationMetadata MD) {
759  Constant *LocData[] = {
760      createPrivateGlobalForString(M, MD.Filename, true),
761      ConstantInt::get(Type::getInt32Ty(M.getContext()), MD.LineNo),
762      ConstantInt::get(Type::getInt32Ty(M.getContext()), MD.ColumnNo),
763  };
764  auto LocStruct = ConstantStruct::getAnon(LocData);
765  auto GV = new GlobalVariable(M, LocStruct->getType(), true,
766                               GlobalValue::PrivateLinkage, LocStruct,
767                               kAsanGenPrefix);
768  GV->setUnnamedAddr(true);
769  return GV;
770}
771
772static bool GlobalWasGeneratedByAsan(GlobalVariable *G) {
773  return G->getName().find(kAsanGenPrefix) == 0 ||
774         G->getName().find(kSanCovGenPrefix) == 0;
775}
776
777Value *AddressSanitizer::memToShadow(Value *Shadow, IRBuilder<> &IRB) {
778  // Shadow >> scale
779  Shadow = IRB.CreateLShr(Shadow, Mapping.Scale);
780  if (Mapping.Offset == 0) return Shadow;
781  // (Shadow >> scale) | offset
782  if (Mapping.OrShadowOffset)
783    return IRB.CreateOr(Shadow, ConstantInt::get(IntptrTy, Mapping.Offset));
784  else
785    return IRB.CreateAdd(Shadow, ConstantInt::get(IntptrTy, Mapping.Offset));
786}
787
788// Instrument memset/memmove/memcpy
789void AddressSanitizer::instrumentMemIntrinsic(MemIntrinsic *MI) {
790  IRBuilder<> IRB(MI);
791  if (isa<MemTransferInst>(MI)) {
792    IRB.CreateCall3(
793        isa<MemMoveInst>(MI) ? AsanMemmove : AsanMemcpy,
794        IRB.CreatePointerCast(MI->getOperand(0), IRB.getInt8PtrTy()),
795        IRB.CreatePointerCast(MI->getOperand(1), IRB.getInt8PtrTy()),
796        IRB.CreateIntCast(MI->getOperand(2), IntptrTy, false));
797  } else if (isa<MemSetInst>(MI)) {
798    IRB.CreateCall3(
799        AsanMemset,
800        IRB.CreatePointerCast(MI->getOperand(0), IRB.getInt8PtrTy()),
801        IRB.CreateIntCast(MI->getOperand(1), IRB.getInt32Ty(), false),
802        IRB.CreateIntCast(MI->getOperand(2), IntptrTy, false));
803  }
804  MI->eraseFromParent();
805}
806
807/// Check if we want (and can) handle this alloca.
808bool AddressSanitizer::isInterestingAlloca(AllocaInst &AI) {
809  auto PreviouslySeenAllocaInfo = ProcessedAllocas.find(&AI);
810
811  if (PreviouslySeenAllocaInfo != ProcessedAllocas.end())
812    return PreviouslySeenAllocaInfo->getSecond();
813
814  bool IsInteresting = (AI.getAllocatedType()->isSized() &&
815    // alloca() may be called with 0 size, ignore it.
816    getAllocaSizeInBytes(&AI) > 0 &&
817    // We are only interested in allocas not promotable to registers.
818    // Promotable allocas are common under -O0.
819    (!ClSkipPromotableAllocas || !isAllocaPromotable(&AI)));
820
821  ProcessedAllocas[&AI] = IsInteresting;
822  return IsInteresting;
823}
824
825/// If I is an interesting memory access, return the PointerOperand
826/// and set IsWrite/Alignment. Otherwise return nullptr.
827Value *AddressSanitizer::isInterestingMemoryAccess(Instruction *I,
828                                                   bool *IsWrite,
829                                                   uint64_t *TypeSize,
830                                                   unsigned *Alignment) {
831  // Skip memory accesses inserted by another instrumentation.
832  if (I->getMetadata("nosanitize")) return nullptr;
833
834  Value *PtrOperand = nullptr;
835  const DataLayout &DL = I->getModule()->getDataLayout();
836  if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
837    if (!ClInstrumentReads) return nullptr;
838    *IsWrite = false;
839    *TypeSize = DL.getTypeStoreSizeInBits(LI->getType());
840    *Alignment = LI->getAlignment();
841    PtrOperand = LI->getPointerOperand();
842  } else if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
843    if (!ClInstrumentWrites) return nullptr;
844    *IsWrite = true;
845    *TypeSize = DL.getTypeStoreSizeInBits(SI->getValueOperand()->getType());
846    *Alignment = SI->getAlignment();
847    PtrOperand = SI->getPointerOperand();
848  } else if (AtomicRMWInst *RMW = dyn_cast<AtomicRMWInst>(I)) {
849    if (!ClInstrumentAtomics) return nullptr;
850    *IsWrite = true;
851    *TypeSize = DL.getTypeStoreSizeInBits(RMW->getValOperand()->getType());
852    *Alignment = 0;
853    PtrOperand = RMW->getPointerOperand();
854  } else if (AtomicCmpXchgInst *XCHG = dyn_cast<AtomicCmpXchgInst>(I)) {
855    if (!ClInstrumentAtomics) return nullptr;
856    *IsWrite = true;
857    *TypeSize = DL.getTypeStoreSizeInBits(XCHG->getCompareOperand()->getType());
858    *Alignment = 0;
859    PtrOperand = XCHG->getPointerOperand();
860  }
861
862  // Treat memory accesses to promotable allocas as non-interesting since they
863  // will not cause memory violations. This greatly speeds up the instrumented
864  // executable at -O0.
865  if (ClSkipPromotableAllocas)
866    if (auto AI = dyn_cast_or_null<AllocaInst>(PtrOperand))
867      return isInterestingAlloca(*AI) ? AI : nullptr;
868
869  return PtrOperand;
870}
871
872static bool isPointerOperand(Value *V) {
873  return V->getType()->isPointerTy() || isa<PtrToIntInst>(V);
874}
875
876// This is a rough heuristic; it may cause both false positives and
877// false negatives. The proper implementation requires cooperation with
878// the frontend.
879static bool isInterestingPointerComparisonOrSubtraction(Instruction *I) {
880  if (ICmpInst *Cmp = dyn_cast<ICmpInst>(I)) {
881    if (!Cmp->isRelational()) return false;
882  } else if (BinaryOperator *BO = dyn_cast<BinaryOperator>(I)) {
883    if (BO->getOpcode() != Instruction::Sub) return false;
884  } else {
885    return false;
886  }
887  if (!isPointerOperand(I->getOperand(0)) ||
888      !isPointerOperand(I->getOperand(1)))
889    return false;
890  return true;
891}
892
893bool AddressSanitizer::GlobalIsLinkerInitialized(GlobalVariable *G) {
894  // If a global variable does not have dynamic initialization we don't
895  // have to instrument it.  However, if a global does not have initializer
896  // at all, we assume it has dynamic initializer (in other TU).
897  return G->hasInitializer() && !GlobalsMD.get(G).IsDynInit;
898}
899
900void AddressSanitizer::instrumentPointerComparisonOrSubtraction(
901    Instruction *I) {
902  IRBuilder<> IRB(I);
903  Function *F = isa<ICmpInst>(I) ? AsanPtrCmpFunction : AsanPtrSubFunction;
904  Value *Param[2] = {I->getOperand(0), I->getOperand(1)};
905  for (int i = 0; i < 2; i++) {
906    if (Param[i]->getType()->isPointerTy())
907      Param[i] = IRB.CreatePointerCast(Param[i], IntptrTy);
908  }
909  IRB.CreateCall2(F, Param[0], Param[1]);
910}
911
912void AddressSanitizer::instrumentMop(ObjectSizeOffsetVisitor &ObjSizeVis,
913                                     Instruction *I, bool UseCalls,
914                                     const DataLayout &DL) {
915  bool IsWrite = false;
916  unsigned Alignment = 0;
917  uint64_t TypeSize = 0;
918  Value *Addr = isInterestingMemoryAccess(I, &IsWrite, &TypeSize, &Alignment);
919  assert(Addr);
920
921  // Optimization experiments.
922  // The experiments can be used to evaluate potential optimizations that remove
923  // instrumentation (assess false negatives). Instead of completely removing
924  // some instrumentation, you set Exp to a non-zero value (mask of optimization
925  // experiments that want to remove instrumentation of this instruction).
926  // If Exp is non-zero, this pass will emit special calls into runtime
927  // (e.g. __asan_report_exp_load1 instead of __asan_report_load1). These calls
928  // make runtime terminate the program in a special way (with a different
929  // exit status). Then you run the new compiler on a buggy corpus, collect
930  // the special terminations (ideally, you don't see them at all -- no false
931  // negatives) and make the decision on the optimization.
932  uint32_t Exp = ClForceExperiment;
933
934  if (ClOpt && ClOptGlobals) {
935    // If initialization order checking is disabled, a simple access to a
936    // dynamically initialized global is always valid.
937    GlobalVariable *G = dyn_cast<GlobalVariable>(GetUnderlyingObject(Addr, DL));
938    if (G != NULL && (!ClInitializers || GlobalIsLinkerInitialized(G)) &&
939        isSafeAccess(ObjSizeVis, Addr, TypeSize)) {
940      NumOptimizedAccessesToGlobalVar++;
941      return;
942    }
943  }
944
945  if (ClOpt && ClOptStack) {
946    // A direct inbounds access to a stack variable is always valid.
947    if (isa<AllocaInst>(GetUnderlyingObject(Addr, DL)) &&
948        isSafeAccess(ObjSizeVis, Addr, TypeSize)) {
949      NumOptimizedAccessesToStackVar++;
950      return;
951    }
952  }
953
954  if (IsWrite)
955    NumInstrumentedWrites++;
956  else
957    NumInstrumentedReads++;
958
959  unsigned Granularity = 1 << Mapping.Scale;
960  // Instrument a 1-, 2-, 4-, 8-, or 16- byte access with one check
961  // if the data is properly aligned.
962  if ((TypeSize == 8 || TypeSize == 16 || TypeSize == 32 || TypeSize == 64 ||
963       TypeSize == 128) &&
964      (Alignment >= Granularity || Alignment == 0 || Alignment >= TypeSize / 8))
965    return instrumentAddress(I, I, Addr, TypeSize, IsWrite, nullptr, UseCalls,
966                             Exp);
967  instrumentUnusualSizeOrAlignment(I, Addr, TypeSize, IsWrite, nullptr,
968                                   UseCalls, Exp);
969}
970
971Instruction *AddressSanitizer::generateCrashCode(Instruction *InsertBefore,
972                                                 Value *Addr, bool IsWrite,
973                                                 size_t AccessSizeIndex,
974                                                 Value *SizeArgument,
975                                                 uint32_t Exp) {
976  IRBuilder<> IRB(InsertBefore);
977  Value *ExpVal = Exp == 0 ? nullptr : ConstantInt::get(IRB.getInt32Ty(), Exp);
978  CallInst *Call = nullptr;
979  if (SizeArgument) {
980    if (Exp == 0)
981      Call = IRB.CreateCall2(AsanErrorCallbackSized[IsWrite][0], Addr,
982                             SizeArgument);
983    else
984      Call = IRB.CreateCall3(AsanErrorCallbackSized[IsWrite][1], Addr,
985                             SizeArgument, ExpVal);
986  } else {
987    if (Exp == 0)
988      Call =
989          IRB.CreateCall(AsanErrorCallback[IsWrite][0][AccessSizeIndex], Addr);
990    else
991      Call = IRB.CreateCall2(AsanErrorCallback[IsWrite][1][AccessSizeIndex],
992                             Addr, ExpVal);
993  }
994
995  // We don't do Call->setDoesNotReturn() because the BB already has
996  // UnreachableInst at the end.
997  // This EmptyAsm is required to avoid callback merge.
998  IRB.CreateCall(EmptyAsm);
999  return Call;
1000}
1001
1002Value *AddressSanitizer::createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
1003                                           Value *ShadowValue,
1004                                           uint32_t TypeSize) {
1005  size_t Granularity = 1 << Mapping.Scale;
1006  // Addr & (Granularity - 1)
1007  Value *LastAccessedByte =
1008      IRB.CreateAnd(AddrLong, ConstantInt::get(IntptrTy, Granularity - 1));
1009  // (Addr & (Granularity - 1)) + size - 1
1010  if (TypeSize / 8 > 1)
1011    LastAccessedByte = IRB.CreateAdd(
1012        LastAccessedByte, ConstantInt::get(IntptrTy, TypeSize / 8 - 1));
1013  // (uint8_t) ((Addr & (Granularity-1)) + size - 1)
1014  LastAccessedByte =
1015      IRB.CreateIntCast(LastAccessedByte, ShadowValue->getType(), false);
1016  // ((uint8_t) ((Addr & (Granularity-1)) + size - 1)) >= ShadowValue
1017  return IRB.CreateICmpSGE(LastAccessedByte, ShadowValue);
1018}
1019
1020void AddressSanitizer::instrumentAddress(Instruction *OrigIns,
1021                                         Instruction *InsertBefore, Value *Addr,
1022                                         uint32_t TypeSize, bool IsWrite,
1023                                         Value *SizeArgument, bool UseCalls,
1024                                         uint32_t Exp) {
1025  IRBuilder<> IRB(InsertBefore);
1026  Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
1027  size_t AccessSizeIndex = TypeSizeToSizeIndex(TypeSize);
1028
1029  if (UseCalls) {
1030    if (Exp == 0)
1031      IRB.CreateCall(AsanMemoryAccessCallback[IsWrite][0][AccessSizeIndex],
1032                     AddrLong);
1033    else
1034      IRB.CreateCall2(AsanMemoryAccessCallback[IsWrite][1][AccessSizeIndex],
1035                      AddrLong, ConstantInt::get(IRB.getInt32Ty(), Exp));
1036    return;
1037  }
1038
1039  Type *ShadowTy =
1040      IntegerType::get(*C, std::max(8U, TypeSize >> Mapping.Scale));
1041  Type *ShadowPtrTy = PointerType::get(ShadowTy, 0);
1042  Value *ShadowPtr = memToShadow(AddrLong, IRB);
1043  Value *CmpVal = Constant::getNullValue(ShadowTy);
1044  Value *ShadowValue =
1045      IRB.CreateLoad(IRB.CreateIntToPtr(ShadowPtr, ShadowPtrTy));
1046
1047  Value *Cmp = IRB.CreateICmpNE(ShadowValue, CmpVal);
1048  size_t Granularity = 1 << Mapping.Scale;
1049  TerminatorInst *CrashTerm = nullptr;
1050
1051  if (ClAlwaysSlowPath || (TypeSize < 8 * Granularity)) {
1052    // We use branch weights for the slow path check, to indicate that the slow
1053    // path is rarely taken. This seems to be the case for SPEC benchmarks.
1054    TerminatorInst *CheckTerm = SplitBlockAndInsertIfThen(
1055        Cmp, InsertBefore, false, MDBuilder(*C).createBranchWeights(1, 100000));
1056    assert(cast<BranchInst>(CheckTerm)->isUnconditional());
1057    BasicBlock *NextBB = CheckTerm->getSuccessor(0);
1058    IRB.SetInsertPoint(CheckTerm);
1059    Value *Cmp2 = createSlowPathCmp(IRB, AddrLong, ShadowValue, TypeSize);
1060    BasicBlock *CrashBlock =
1061        BasicBlock::Create(*C, "", NextBB->getParent(), NextBB);
1062    CrashTerm = new UnreachableInst(*C, CrashBlock);
1063    BranchInst *NewTerm = BranchInst::Create(CrashBlock, NextBB, Cmp2);
1064    ReplaceInstWithInst(CheckTerm, NewTerm);
1065  } else {
1066    CrashTerm = SplitBlockAndInsertIfThen(Cmp, InsertBefore, true);
1067  }
1068
1069  Instruction *Crash = generateCrashCode(CrashTerm, AddrLong, IsWrite,
1070                                         AccessSizeIndex, SizeArgument, Exp);
1071  Crash->setDebugLoc(OrigIns->getDebugLoc());
1072}
1073
1074// Instrument unusual size or unusual alignment.
1075// We can not do it with a single check, so we do 1-byte check for the first
1076// and the last bytes. We call __asan_report_*_n(addr, real_size) to be able
1077// to report the actual access size.
1078void AddressSanitizer::instrumentUnusualSizeOrAlignment(
1079    Instruction *I, Value *Addr, uint32_t TypeSize, bool IsWrite,
1080    Value *SizeArgument, bool UseCalls, uint32_t Exp) {
1081  IRBuilder<> IRB(I);
1082  Value *Size = ConstantInt::get(IntptrTy, TypeSize / 8);
1083  Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
1084  if (UseCalls) {
1085    if (Exp == 0)
1086      IRB.CreateCall2(AsanMemoryAccessCallbackSized[IsWrite][0], AddrLong,
1087                      Size);
1088    else
1089      IRB.CreateCall3(AsanMemoryAccessCallbackSized[IsWrite][1], AddrLong, Size,
1090                      ConstantInt::get(IRB.getInt32Ty(), Exp));
1091  } else {
1092    Value *LastByte = IRB.CreateIntToPtr(
1093        IRB.CreateAdd(AddrLong, ConstantInt::get(IntptrTy, TypeSize / 8 - 1)),
1094        Addr->getType());
1095    instrumentAddress(I, I, Addr, 8, IsWrite, Size, false, Exp);
1096    instrumentAddress(I, I, LastByte, 8, IsWrite, Size, false, Exp);
1097  }
1098}
1099
1100void AddressSanitizerModule::poisonOneInitializer(Function &GlobalInit,
1101                                                  GlobalValue *ModuleName) {
1102  // Set up the arguments to our poison/unpoison functions.
1103  IRBuilder<> IRB(GlobalInit.begin()->getFirstInsertionPt());
1104
1105  // Add a call to poison all external globals before the given function starts.
1106  Value *ModuleNameAddr = ConstantExpr::getPointerCast(ModuleName, IntptrTy);
1107  IRB.CreateCall(AsanPoisonGlobals, ModuleNameAddr);
1108
1109  // Add calls to unpoison all globals before each return instruction.
1110  for (auto &BB : GlobalInit.getBasicBlockList())
1111    if (ReturnInst *RI = dyn_cast<ReturnInst>(BB.getTerminator()))
1112      CallInst::Create(AsanUnpoisonGlobals, "", RI);
1113}
1114
1115void AddressSanitizerModule::createInitializerPoisonCalls(
1116    Module &M, GlobalValue *ModuleName) {
1117  GlobalVariable *GV = M.getGlobalVariable("llvm.global_ctors");
1118
1119  ConstantArray *CA = cast<ConstantArray>(GV->getInitializer());
1120  for (Use &OP : CA->operands()) {
1121    if (isa<ConstantAggregateZero>(OP)) continue;
1122    ConstantStruct *CS = cast<ConstantStruct>(OP);
1123
1124    // Must have a function or null ptr.
1125    if (Function *F = dyn_cast<Function>(CS->getOperand(1))) {
1126      if (F->getName() == kAsanModuleCtorName) continue;
1127      ConstantInt *Priority = dyn_cast<ConstantInt>(CS->getOperand(0));
1128      // Don't instrument CTORs that will run before asan.module_ctor.
1129      if (Priority->getLimitedValue() <= kAsanCtorAndDtorPriority) continue;
1130      poisonOneInitializer(*F, ModuleName);
1131    }
1132  }
1133}
1134
1135bool AddressSanitizerModule::ShouldInstrumentGlobal(GlobalVariable *G) {
1136  Type *Ty = cast<PointerType>(G->getType())->getElementType();
1137  DEBUG(dbgs() << "GLOBAL: " << *G << "\n");
1138
1139  if (GlobalsMD.get(G).IsBlacklisted) return false;
1140  if (!Ty->isSized()) return false;
1141  if (!G->hasInitializer()) return false;
1142  if (GlobalWasGeneratedByAsan(G)) return false;  // Our own global.
1143  // Touch only those globals that will not be defined in other modules.
1144  // Don't handle ODR linkage types and COMDATs since other modules may be built
1145  // without ASan.
1146  if (G->getLinkage() != GlobalVariable::ExternalLinkage &&
1147      G->getLinkage() != GlobalVariable::PrivateLinkage &&
1148      G->getLinkage() != GlobalVariable::InternalLinkage)
1149    return false;
1150  if (G->hasComdat()) return false;
1151  // Two problems with thread-locals:
1152  //   - The address of the main thread's copy can't be computed at link-time.
1153  //   - Need to poison all copies, not just the main thread's one.
1154  if (G->isThreadLocal()) return false;
1155  // For now, just ignore this Global if the alignment is large.
1156  if (G->getAlignment() > MinRedzoneSizeForGlobal()) return false;
1157
1158  if (G->hasSection()) {
1159    StringRef Section(G->getSection());
1160
1161    if (TargetTriple.isOSBinFormatMachO()) {
1162      StringRef ParsedSegment, ParsedSection;
1163      unsigned TAA = 0, StubSize = 0;
1164      bool TAAParsed;
1165      std::string ErrorCode = MCSectionMachO::ParseSectionSpecifier(
1166          Section, ParsedSegment, ParsedSection, TAA, TAAParsed, StubSize);
1167      if (!ErrorCode.empty()) {
1168        report_fatal_error("Invalid section specifier '" + ParsedSection +
1169                           "': " + ErrorCode + ".");
1170      }
1171
1172      // Ignore the globals from the __OBJC section. The ObjC runtime assumes
1173      // those conform to /usr/lib/objc/runtime.h, so we can't add redzones to
1174      // them.
1175      if (ParsedSegment == "__OBJC" ||
1176          (ParsedSegment == "__DATA" && ParsedSection.startswith("__objc_"))) {
1177        DEBUG(dbgs() << "Ignoring ObjC runtime global: " << *G << "\n");
1178        return false;
1179      }
1180      // See http://code.google.com/p/address-sanitizer/issues/detail?id=32
1181      // Constant CFString instances are compiled in the following way:
1182      //  -- the string buffer is emitted into
1183      //     __TEXT,__cstring,cstring_literals
1184      //  -- the constant NSConstantString structure referencing that buffer
1185      //     is placed into __DATA,__cfstring
1186      // Therefore there's no point in placing redzones into __DATA,__cfstring.
1187      // Moreover, it causes the linker to crash on OS X 10.7
1188      if (ParsedSegment == "__DATA" && ParsedSection == "__cfstring") {
1189        DEBUG(dbgs() << "Ignoring CFString: " << *G << "\n");
1190        return false;
1191      }
1192      // The linker merges the contents of cstring_literals and removes the
1193      // trailing zeroes.
1194      if (ParsedSegment == "__TEXT" && (TAA & MachO::S_CSTRING_LITERALS)) {
1195        DEBUG(dbgs() << "Ignoring a cstring literal: " << *G << "\n");
1196        return false;
1197      }
1198    }
1199
1200    // Callbacks put into the CRT initializer/terminator sections
1201    // should not be instrumented.
1202    // See https://code.google.com/p/address-sanitizer/issues/detail?id=305
1203    // and http://msdn.microsoft.com/en-US/en-en/library/bb918180(v=vs.120).aspx
1204    if (Section.startswith(".CRT")) {
1205      DEBUG(dbgs() << "Ignoring a global initializer callback: " << *G << "\n");
1206      return false;
1207    }
1208
1209    // Globals from llvm.metadata aren't emitted, do not instrument them.
1210    if (Section == "llvm.metadata") return false;
1211  }
1212
1213  return true;
1214}
1215
1216void AddressSanitizerModule::initializeCallbacks(Module &M) {
1217  IRBuilder<> IRB(*C);
1218  // Declare our poisoning and unpoisoning functions.
1219  AsanPoisonGlobals = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1220      kAsanPoisonGlobalsName, IRB.getVoidTy(), IntptrTy, nullptr));
1221  AsanPoisonGlobals->setLinkage(Function::ExternalLinkage);
1222  AsanUnpoisonGlobals = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1223      kAsanUnpoisonGlobalsName, IRB.getVoidTy(), nullptr));
1224  AsanUnpoisonGlobals->setLinkage(Function::ExternalLinkage);
1225  // Declare functions that register/unregister globals.
1226  AsanRegisterGlobals = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1227      kAsanRegisterGlobalsName, IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
1228  AsanRegisterGlobals->setLinkage(Function::ExternalLinkage);
1229  AsanUnregisterGlobals = checkSanitizerInterfaceFunction(
1230      M.getOrInsertFunction(kAsanUnregisterGlobalsName, IRB.getVoidTy(),
1231                            IntptrTy, IntptrTy, nullptr));
1232  AsanUnregisterGlobals->setLinkage(Function::ExternalLinkage);
1233}
1234
1235// This function replaces all global variables with new variables that have
1236// trailing redzones. It also creates a function that poisons
1237// redzones and inserts this function into llvm.global_ctors.
1238bool AddressSanitizerModule::InstrumentGlobals(IRBuilder<> &IRB, Module &M) {
1239  GlobalsMD.init(M);
1240
1241  SmallVector<GlobalVariable *, 16> GlobalsToChange;
1242
1243  for (auto &G : M.globals()) {
1244    if (ShouldInstrumentGlobal(&G)) GlobalsToChange.push_back(&G);
1245  }
1246
1247  size_t n = GlobalsToChange.size();
1248  if (n == 0) return false;
1249
1250  // A global is described by a structure
1251  //   size_t beg;
1252  //   size_t size;
1253  //   size_t size_with_redzone;
1254  //   const char *name;
1255  //   const char *module_name;
1256  //   size_t has_dynamic_init;
1257  //   void *source_location;
1258  // We initialize an array of such structures and pass it to a run-time call.
1259  StructType *GlobalStructTy =
1260      StructType::get(IntptrTy, IntptrTy, IntptrTy, IntptrTy, IntptrTy,
1261                      IntptrTy, IntptrTy, nullptr);
1262  SmallVector<Constant *, 16> Initializers(n);
1263
1264  bool HasDynamicallyInitializedGlobals = false;
1265
1266  // We shouldn't merge same module names, as this string serves as unique
1267  // module ID in runtime.
1268  GlobalVariable *ModuleName = createPrivateGlobalForString(
1269      M, M.getModuleIdentifier(), /*AllowMerging*/ false);
1270
1271  auto &DL = M.getDataLayout();
1272  for (size_t i = 0; i < n; i++) {
1273    static const uint64_t kMaxGlobalRedzone = 1 << 18;
1274    GlobalVariable *G = GlobalsToChange[i];
1275
1276    auto MD = GlobalsMD.get(G);
1277    // Create string holding the global name (use global name from metadata
1278    // if it's available, otherwise just write the name of global variable).
1279    GlobalVariable *Name = createPrivateGlobalForString(
1280        M, MD.Name.empty() ? G->getName() : MD.Name,
1281        /*AllowMerging*/ true);
1282
1283    PointerType *PtrTy = cast<PointerType>(G->getType());
1284    Type *Ty = PtrTy->getElementType();
1285    uint64_t SizeInBytes = DL.getTypeAllocSize(Ty);
1286    uint64_t MinRZ = MinRedzoneSizeForGlobal();
1287    // MinRZ <= RZ <= kMaxGlobalRedzone
1288    // and trying to make RZ to be ~ 1/4 of SizeInBytes.
1289    uint64_t RZ = std::max(
1290        MinRZ, std::min(kMaxGlobalRedzone, (SizeInBytes / MinRZ / 4) * MinRZ));
1291    uint64_t RightRedzoneSize = RZ;
1292    // Round up to MinRZ
1293    if (SizeInBytes % MinRZ) RightRedzoneSize += MinRZ - (SizeInBytes % MinRZ);
1294    assert(((RightRedzoneSize + SizeInBytes) % MinRZ) == 0);
1295    Type *RightRedZoneTy = ArrayType::get(IRB.getInt8Ty(), RightRedzoneSize);
1296
1297    StructType *NewTy = StructType::get(Ty, RightRedZoneTy, nullptr);
1298    Constant *NewInitializer =
1299        ConstantStruct::get(NewTy, G->getInitializer(),
1300                            Constant::getNullValue(RightRedZoneTy), nullptr);
1301
1302    // Create a new global variable with enough space for a redzone.
1303    GlobalValue::LinkageTypes Linkage = G->getLinkage();
1304    if (G->isConstant() && Linkage == GlobalValue::PrivateLinkage)
1305      Linkage = GlobalValue::InternalLinkage;
1306    GlobalVariable *NewGlobal =
1307        new GlobalVariable(M, NewTy, G->isConstant(), Linkage, NewInitializer,
1308                           "", G, G->getThreadLocalMode());
1309    NewGlobal->copyAttributesFrom(G);
1310    NewGlobal->setAlignment(MinRZ);
1311
1312    Value *Indices2[2];
1313    Indices2[0] = IRB.getInt32(0);
1314    Indices2[1] = IRB.getInt32(0);
1315
1316    G->replaceAllUsesWith(
1317        ConstantExpr::getGetElementPtr(NewTy, NewGlobal, Indices2, true));
1318    NewGlobal->takeName(G);
1319    G->eraseFromParent();
1320
1321    Constant *SourceLoc;
1322    if (!MD.SourceLoc.empty()) {
1323      auto SourceLocGlobal = createPrivateGlobalForSourceLoc(M, MD.SourceLoc);
1324      SourceLoc = ConstantExpr::getPointerCast(SourceLocGlobal, IntptrTy);
1325    } else {
1326      SourceLoc = ConstantInt::get(IntptrTy, 0);
1327    }
1328
1329    Initializers[i] = ConstantStruct::get(
1330        GlobalStructTy, ConstantExpr::getPointerCast(NewGlobal, IntptrTy),
1331        ConstantInt::get(IntptrTy, SizeInBytes),
1332        ConstantInt::get(IntptrTy, SizeInBytes + RightRedzoneSize),
1333        ConstantExpr::getPointerCast(Name, IntptrTy),
1334        ConstantExpr::getPointerCast(ModuleName, IntptrTy),
1335        ConstantInt::get(IntptrTy, MD.IsDynInit), SourceLoc, nullptr);
1336
1337    if (ClInitializers && MD.IsDynInit) HasDynamicallyInitializedGlobals = true;
1338
1339    DEBUG(dbgs() << "NEW GLOBAL: " << *NewGlobal << "\n");
1340  }
1341
1342  ArrayType *ArrayOfGlobalStructTy = ArrayType::get(GlobalStructTy, n);
1343  GlobalVariable *AllGlobals = new GlobalVariable(
1344      M, ArrayOfGlobalStructTy, false, GlobalVariable::InternalLinkage,
1345      ConstantArray::get(ArrayOfGlobalStructTy, Initializers), "");
1346
1347  // Create calls for poisoning before initializers run and unpoisoning after.
1348  if (HasDynamicallyInitializedGlobals)
1349    createInitializerPoisonCalls(M, ModuleName);
1350  IRB.CreateCall2(AsanRegisterGlobals,
1351                  IRB.CreatePointerCast(AllGlobals, IntptrTy),
1352                  ConstantInt::get(IntptrTy, n));
1353
1354  // We also need to unregister globals at the end, e.g. when a shared library
1355  // gets closed.
1356  Function *AsanDtorFunction =
1357      Function::Create(FunctionType::get(Type::getVoidTy(*C), false),
1358                       GlobalValue::InternalLinkage, kAsanModuleDtorName, &M);
1359  BasicBlock *AsanDtorBB = BasicBlock::Create(*C, "", AsanDtorFunction);
1360  IRBuilder<> IRB_Dtor(ReturnInst::Create(*C, AsanDtorBB));
1361  IRB_Dtor.CreateCall2(AsanUnregisterGlobals,
1362                       IRB.CreatePointerCast(AllGlobals, IntptrTy),
1363                       ConstantInt::get(IntptrTy, n));
1364  appendToGlobalDtors(M, AsanDtorFunction, kAsanCtorAndDtorPriority);
1365
1366  DEBUG(dbgs() << M);
1367  return true;
1368}
1369
1370bool AddressSanitizerModule::runOnModule(Module &M) {
1371  C = &(M.getContext());
1372  int LongSize = M.getDataLayout().getPointerSizeInBits();
1373  IntptrTy = Type::getIntNTy(*C, LongSize);
1374  TargetTriple = Triple(M.getTargetTriple());
1375  Mapping = getShadowMapping(TargetTriple, LongSize);
1376  initializeCallbacks(M);
1377
1378  bool Changed = false;
1379
1380  Function *CtorFunc = M.getFunction(kAsanModuleCtorName);
1381  assert(CtorFunc);
1382  IRBuilder<> IRB(CtorFunc->getEntryBlock().getTerminator());
1383
1384  if (ClGlobals) Changed |= InstrumentGlobals(IRB, M);
1385
1386  return Changed;
1387}
1388
1389void AddressSanitizer::initializeCallbacks(Module &M) {
1390  IRBuilder<> IRB(*C);
1391  // Create __asan_report* callbacks.
1392  // IsWrite, TypeSize and Exp are encoded in the function name.
1393  for (int Exp = 0; Exp < 2; Exp++) {
1394    for (size_t AccessIsWrite = 0; AccessIsWrite <= 1; AccessIsWrite++) {
1395      const std::string TypeStr = AccessIsWrite ? "store" : "load";
1396      const std::string ExpStr = Exp ? "exp_" : "";
1397      const Type *ExpType = Exp ? Type::getInt32Ty(*C) : nullptr;
1398      AsanErrorCallbackSized[AccessIsWrite][Exp] =
1399          checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1400              kAsanReportErrorTemplate + ExpStr + TypeStr + "_n",
1401              IRB.getVoidTy(), IntptrTy, IntptrTy, ExpType, nullptr));
1402      AsanMemoryAccessCallbackSized[AccessIsWrite][Exp] =
1403          checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1404              ClMemoryAccessCallbackPrefix + ExpStr + TypeStr + "N",
1405              IRB.getVoidTy(), IntptrTy, IntptrTy, ExpType, nullptr));
1406      for (size_t AccessSizeIndex = 0; AccessSizeIndex < kNumberOfAccessSizes;
1407           AccessSizeIndex++) {
1408        const std::string Suffix = TypeStr + itostr(1 << AccessSizeIndex);
1409        AsanErrorCallback[AccessIsWrite][Exp][AccessSizeIndex] =
1410            checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1411                kAsanReportErrorTemplate + ExpStr + Suffix, IRB.getVoidTy(),
1412                IntptrTy, ExpType, nullptr));
1413        AsanMemoryAccessCallback[AccessIsWrite][Exp][AccessSizeIndex] =
1414            checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1415                ClMemoryAccessCallbackPrefix + ExpStr + Suffix, IRB.getVoidTy(),
1416                IntptrTy, ExpType, nullptr));
1417      }
1418    }
1419  }
1420
1421  AsanMemmove = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1422      ClMemoryAccessCallbackPrefix + "memmove", IRB.getInt8PtrTy(),
1423      IRB.getInt8PtrTy(), IRB.getInt8PtrTy(), IntptrTy, nullptr));
1424  AsanMemcpy = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1425      ClMemoryAccessCallbackPrefix + "memcpy", IRB.getInt8PtrTy(),
1426      IRB.getInt8PtrTy(), IRB.getInt8PtrTy(), IntptrTy, nullptr));
1427  AsanMemset = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1428      ClMemoryAccessCallbackPrefix + "memset", IRB.getInt8PtrTy(),
1429      IRB.getInt8PtrTy(), IRB.getInt32Ty(), IntptrTy, nullptr));
1430
1431  AsanHandleNoReturnFunc = checkSanitizerInterfaceFunction(
1432      M.getOrInsertFunction(kAsanHandleNoReturnName, IRB.getVoidTy(), nullptr));
1433
1434  AsanPtrCmpFunction = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1435      kAsanPtrCmp, IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
1436  AsanPtrSubFunction = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1437      kAsanPtrSub, IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
1438  // We insert an empty inline asm after __asan_report* to avoid callback merge.
1439  EmptyAsm = InlineAsm::get(FunctionType::get(IRB.getVoidTy(), false),
1440                            StringRef(""), StringRef(""),
1441                            /*hasSideEffects=*/true);
1442}
1443
1444// virtual
1445bool AddressSanitizer::doInitialization(Module &M) {
1446  // Initialize the private fields. No one has accessed them before.
1447
1448  GlobalsMD.init(M);
1449
1450  C = &(M.getContext());
1451  LongSize = M.getDataLayout().getPointerSizeInBits();
1452  IntptrTy = Type::getIntNTy(*C, LongSize);
1453  TargetTriple = Triple(M.getTargetTriple());
1454
1455  AsanCtorFunction =
1456      Function::Create(FunctionType::get(Type::getVoidTy(*C), false),
1457                       GlobalValue::InternalLinkage, kAsanModuleCtorName, &M);
1458  BasicBlock *AsanCtorBB = BasicBlock::Create(*C, "", AsanCtorFunction);
1459  // call __asan_init in the module ctor.
1460  IRBuilder<> IRB(ReturnInst::Create(*C, AsanCtorBB));
1461  AsanInitFunction = checkSanitizerInterfaceFunction(
1462      M.getOrInsertFunction(kAsanInitName, IRB.getVoidTy(), nullptr));
1463  AsanInitFunction->setLinkage(Function::ExternalLinkage);
1464  IRB.CreateCall(AsanInitFunction);
1465
1466  Mapping = getShadowMapping(TargetTriple, LongSize);
1467
1468  appendToGlobalCtors(M, AsanCtorFunction, kAsanCtorAndDtorPriority);
1469  return true;
1470}
1471
1472bool AddressSanitizer::maybeInsertAsanInitAtFunctionEntry(Function &F) {
1473  // For each NSObject descendant having a +load method, this method is invoked
1474  // by the ObjC runtime before any of the static constructors is called.
1475  // Therefore we need to instrument such methods with a call to __asan_init
1476  // at the beginning in order to initialize our runtime before any access to
1477  // the shadow memory.
1478  // We cannot just ignore these methods, because they may call other
1479  // instrumented functions.
1480  if (F.getName().find(" load]") != std::string::npos) {
1481    IRBuilder<> IRB(F.begin()->begin());
1482    IRB.CreateCall(AsanInitFunction);
1483    return true;
1484  }
1485  return false;
1486}
1487
1488bool AddressSanitizer::runOnFunction(Function &F) {
1489  if (&F == AsanCtorFunction) return false;
1490  if (F.getLinkage() == GlobalValue::AvailableExternallyLinkage) return false;
1491  DEBUG(dbgs() << "ASAN instrumenting:\n" << F << "\n");
1492  initializeCallbacks(*F.getParent());
1493
1494  DT = &getAnalysis<DominatorTreeWrapperPass>().getDomTree();
1495
1496  // If needed, insert __asan_init before checking for SanitizeAddress attr.
1497  maybeInsertAsanInitAtFunctionEntry(F);
1498
1499  if (!F.hasFnAttribute(Attribute::SanitizeAddress)) return false;
1500
1501  if (!ClDebugFunc.empty() && ClDebugFunc != F.getName()) return false;
1502
1503  // We want to instrument every address only once per basic block (unless there
1504  // are calls between uses).
1505  SmallSet<Value *, 16> TempsToInstrument;
1506  SmallVector<Instruction *, 16> ToInstrument;
1507  SmallVector<Instruction *, 8> NoReturnCalls;
1508  SmallVector<BasicBlock *, 16> AllBlocks;
1509  SmallVector<Instruction *, 16> PointerComparisonsOrSubtracts;
1510  int NumAllocas = 0;
1511  bool IsWrite;
1512  unsigned Alignment;
1513  uint64_t TypeSize;
1514
1515  // Fill the set of memory operations to instrument.
1516  for (auto &BB : F) {
1517    AllBlocks.push_back(&BB);
1518    TempsToInstrument.clear();
1519    int NumInsnsPerBB = 0;
1520    for (auto &Inst : BB) {
1521      if (LooksLikeCodeInBug11395(&Inst)) return false;
1522      if (Value *Addr = isInterestingMemoryAccess(&Inst, &IsWrite, &TypeSize,
1523                                                  &Alignment)) {
1524        if (ClOpt && ClOptSameTemp) {
1525          if (!TempsToInstrument.insert(Addr).second)
1526            continue;  // We've seen this temp in the current BB.
1527        }
1528      } else if (ClInvalidPointerPairs &&
1529                 isInterestingPointerComparisonOrSubtraction(&Inst)) {
1530        PointerComparisonsOrSubtracts.push_back(&Inst);
1531        continue;
1532      } else if (isa<MemIntrinsic>(Inst)) {
1533        // ok, take it.
1534      } else {
1535        if (isa<AllocaInst>(Inst)) NumAllocas++;
1536        CallSite CS(&Inst);
1537        if (CS) {
1538          // A call inside BB.
1539          TempsToInstrument.clear();
1540          if (CS.doesNotReturn()) NoReturnCalls.push_back(CS.getInstruction());
1541        }
1542        continue;
1543      }
1544      ToInstrument.push_back(&Inst);
1545      NumInsnsPerBB++;
1546      if (NumInsnsPerBB >= ClMaxInsnsToInstrumentPerBB) break;
1547    }
1548  }
1549
1550  bool UseCalls = false;
1551  if (ClInstrumentationWithCallsThreshold >= 0 &&
1552      ToInstrument.size() > (unsigned)ClInstrumentationWithCallsThreshold)
1553    UseCalls = true;
1554
1555  const TargetLibraryInfo *TLI =
1556      &getAnalysis<TargetLibraryInfoWrapperPass>().getTLI();
1557  const DataLayout &DL = F.getParent()->getDataLayout();
1558  ObjectSizeOffsetVisitor ObjSizeVis(DL, TLI, F.getContext(),
1559                                     /*RoundToAlign=*/true);
1560
1561  // Instrument.
1562  int NumInstrumented = 0;
1563  for (auto Inst : ToInstrument) {
1564    if (ClDebugMin < 0 || ClDebugMax < 0 ||
1565        (NumInstrumented >= ClDebugMin && NumInstrumented <= ClDebugMax)) {
1566      if (isInterestingMemoryAccess(Inst, &IsWrite, &TypeSize, &Alignment))
1567        instrumentMop(ObjSizeVis, Inst, UseCalls,
1568                      F.getParent()->getDataLayout());
1569      else
1570        instrumentMemIntrinsic(cast<MemIntrinsic>(Inst));
1571    }
1572    NumInstrumented++;
1573  }
1574
1575  FunctionStackPoisoner FSP(F, *this);
1576  bool ChangedStack = FSP.runOnFunction();
1577
1578  // We must unpoison the stack before every NoReturn call (throw, _exit, etc).
1579  // See e.g. http://code.google.com/p/address-sanitizer/issues/detail?id=37
1580  for (auto CI : NoReturnCalls) {
1581    IRBuilder<> IRB(CI);
1582    IRB.CreateCall(AsanHandleNoReturnFunc);
1583  }
1584
1585  for (auto Inst : PointerComparisonsOrSubtracts) {
1586    instrumentPointerComparisonOrSubtraction(Inst);
1587    NumInstrumented++;
1588  }
1589
1590  bool res = NumInstrumented > 0 || ChangedStack || !NoReturnCalls.empty();
1591
1592  DEBUG(dbgs() << "ASAN done instrumenting: " << res << " " << F << "\n");
1593
1594  return res;
1595}
1596
1597// Workaround for bug 11395: we don't want to instrument stack in functions
1598// with large assembly blobs (32-bit only), otherwise reg alloc may crash.
1599// FIXME: remove once the bug 11395 is fixed.
1600bool AddressSanitizer::LooksLikeCodeInBug11395(Instruction *I) {
1601  if (LongSize != 32) return false;
1602  CallInst *CI = dyn_cast<CallInst>(I);
1603  if (!CI || !CI->isInlineAsm()) return false;
1604  if (CI->getNumArgOperands() <= 5) return false;
1605  // We have inline assembly with quite a few arguments.
1606  return true;
1607}
1608
1609void FunctionStackPoisoner::initializeCallbacks(Module &M) {
1610  IRBuilder<> IRB(*C);
1611  for (int i = 0; i <= kMaxAsanStackMallocSizeClass; i++) {
1612    std::string Suffix = itostr(i);
1613    AsanStackMallocFunc[i] = checkSanitizerInterfaceFunction(
1614        M.getOrInsertFunction(kAsanStackMallocNameTemplate + Suffix, IntptrTy,
1615                              IntptrTy, nullptr));
1616    AsanStackFreeFunc[i] = checkSanitizerInterfaceFunction(
1617        M.getOrInsertFunction(kAsanStackFreeNameTemplate + Suffix,
1618                              IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
1619  }
1620  AsanPoisonStackMemoryFunc = checkSanitizerInterfaceFunction(
1621      M.getOrInsertFunction(kAsanPoisonStackMemoryName, IRB.getVoidTy(),
1622                            IntptrTy, IntptrTy, nullptr));
1623  AsanUnpoisonStackMemoryFunc = checkSanitizerInterfaceFunction(
1624      M.getOrInsertFunction(kAsanUnpoisonStackMemoryName, IRB.getVoidTy(),
1625                            IntptrTy, IntptrTy, nullptr));
1626}
1627
1628void FunctionStackPoisoner::poisonRedZones(ArrayRef<uint8_t> ShadowBytes,
1629                                           IRBuilder<> &IRB, Value *ShadowBase,
1630                                           bool DoPoison) {
1631  size_t n = ShadowBytes.size();
1632  size_t i = 0;
1633  // We need to (un)poison n bytes of stack shadow. Poison as many as we can
1634  // using 64-bit stores (if we are on 64-bit arch), then poison the rest
1635  // with 32-bit stores, then with 16-byte stores, then with 8-byte stores.
1636  for (size_t LargeStoreSizeInBytes = ASan.LongSize / 8;
1637       LargeStoreSizeInBytes != 0; LargeStoreSizeInBytes /= 2) {
1638    for (; i + LargeStoreSizeInBytes - 1 < n; i += LargeStoreSizeInBytes) {
1639      uint64_t Val = 0;
1640      for (size_t j = 0; j < LargeStoreSizeInBytes; j++) {
1641        if (F.getParent()->getDataLayout().isLittleEndian())
1642          Val |= (uint64_t)ShadowBytes[i + j] << (8 * j);
1643        else
1644          Val = (Val << 8) | ShadowBytes[i + j];
1645      }
1646      if (!Val) continue;
1647      Value *Ptr = IRB.CreateAdd(ShadowBase, ConstantInt::get(IntptrTy, i));
1648      Type *StoreTy = Type::getIntNTy(*C, LargeStoreSizeInBytes * 8);
1649      Value *Poison = ConstantInt::get(StoreTy, DoPoison ? Val : 0);
1650      IRB.CreateStore(Poison, IRB.CreateIntToPtr(Ptr, StoreTy->getPointerTo()));
1651    }
1652  }
1653}
1654
1655// Fake stack allocator (asan_fake_stack.h) has 11 size classes
1656// for every power of 2 from kMinStackMallocSize to kMaxAsanStackMallocSizeClass
1657static int StackMallocSizeClass(uint64_t LocalStackSize) {
1658  assert(LocalStackSize <= kMaxStackMallocSize);
1659  uint64_t MaxSize = kMinStackMallocSize;
1660  for (int i = 0;; i++, MaxSize *= 2)
1661    if (LocalStackSize <= MaxSize) return i;
1662  llvm_unreachable("impossible LocalStackSize");
1663}
1664
1665// Set Size bytes starting from ShadowBase to kAsanStackAfterReturnMagic.
1666// We can not use MemSet intrinsic because it may end up calling the actual
1667// memset. Size is a multiple of 8.
1668// Currently this generates 8-byte stores on x86_64; it may be better to
1669// generate wider stores.
1670void FunctionStackPoisoner::SetShadowToStackAfterReturnInlined(
1671    IRBuilder<> &IRB, Value *ShadowBase, int Size) {
1672  assert(!(Size % 8));
1673
1674  // kAsanStackAfterReturnMagic is 0xf5.
1675  const uint64_t kAsanStackAfterReturnMagic64 = 0xf5f5f5f5f5f5f5f5ULL;
1676
1677  for (int i = 0; i < Size; i += 8) {
1678    Value *p = IRB.CreateAdd(ShadowBase, ConstantInt::get(IntptrTy, i));
1679    IRB.CreateStore(
1680        ConstantInt::get(IRB.getInt64Ty(), kAsanStackAfterReturnMagic64),
1681        IRB.CreateIntToPtr(p, IRB.getInt64Ty()->getPointerTo()));
1682  }
1683}
1684
1685static DebugLoc getFunctionEntryDebugLocation(Function &F) {
1686  for (const auto &Inst : F.getEntryBlock())
1687    if (!isa<AllocaInst>(Inst)) return Inst.getDebugLoc();
1688  return DebugLoc();
1689}
1690
1691PHINode *FunctionStackPoisoner::createPHI(IRBuilder<> &IRB, Value *Cond,
1692                                          Value *ValueIfTrue,
1693                                          Instruction *ThenTerm,
1694                                          Value *ValueIfFalse) {
1695  PHINode *PHI = IRB.CreatePHI(IntptrTy, 2);
1696  BasicBlock *CondBlock = cast<Instruction>(Cond)->getParent();
1697  PHI->addIncoming(ValueIfFalse, CondBlock);
1698  BasicBlock *ThenBlock = ThenTerm->getParent();
1699  PHI->addIncoming(ValueIfTrue, ThenBlock);
1700  return PHI;
1701}
1702
1703Value *FunctionStackPoisoner::createAllocaForLayout(
1704    IRBuilder<> &IRB, const ASanStackFrameLayout &L, bool Dynamic) {
1705  AllocaInst *Alloca;
1706  if (Dynamic) {
1707    Alloca = IRB.CreateAlloca(IRB.getInt8Ty(),
1708                              ConstantInt::get(IRB.getInt64Ty(), L.FrameSize),
1709                              "MyAlloca");
1710  } else {
1711    Alloca = IRB.CreateAlloca(ArrayType::get(IRB.getInt8Ty(), L.FrameSize),
1712                              nullptr, "MyAlloca");
1713    assert(Alloca->isStaticAlloca());
1714  }
1715  assert((ClRealignStack & (ClRealignStack - 1)) == 0);
1716  size_t FrameAlignment = std::max(L.FrameAlignment, (size_t)ClRealignStack);
1717  Alloca->setAlignment(FrameAlignment);
1718  return IRB.CreatePointerCast(Alloca, IntptrTy);
1719}
1720
1721void FunctionStackPoisoner::poisonStack() {
1722  assert(AllocaVec.size() > 0 || DynamicAllocaVec.size() > 0);
1723
1724  if (ClInstrumentAllocas) {
1725    // Handle dynamic allocas.
1726    for (auto &AllocaCall : DynamicAllocaVec) {
1727      handleDynamicAllocaCall(AllocaCall);
1728      unpoisonDynamicAlloca(AllocaCall);
1729    }
1730  }
1731
1732  if (AllocaVec.size() == 0) return;
1733
1734  int StackMallocIdx = -1;
1735  DebugLoc EntryDebugLocation = getFunctionEntryDebugLocation(F);
1736
1737  Instruction *InsBefore = AllocaVec[0];
1738  IRBuilder<> IRB(InsBefore);
1739  IRB.SetCurrentDebugLocation(EntryDebugLocation);
1740
1741  SmallVector<ASanStackVariableDescription, 16> SVD;
1742  SVD.reserve(AllocaVec.size());
1743  for (AllocaInst *AI : AllocaVec) {
1744    ASanStackVariableDescription D = {AI->getName().data(),
1745                                      ASan.getAllocaSizeInBytes(AI),
1746                                      AI->getAlignment(), AI, 0};
1747    SVD.push_back(D);
1748  }
1749  // Minimal header size (left redzone) is 4 pointers,
1750  // i.e. 32 bytes on 64-bit platforms and 16 bytes in 32-bit platforms.
1751  size_t MinHeaderSize = ASan.LongSize / 2;
1752  ASanStackFrameLayout L;
1753  ComputeASanStackFrameLayout(SVD, 1UL << Mapping.Scale, MinHeaderSize, &L);
1754  DEBUG(dbgs() << L.DescriptionString << " --- " << L.FrameSize << "\n");
1755  uint64_t LocalStackSize = L.FrameSize;
1756  bool DoStackMalloc =
1757      ClUseAfterReturn && LocalStackSize <= kMaxStackMallocSize;
1758  // Don't do dynamic alloca in presence of inline asm: too often it makes
1759  // assumptions on which registers are available. Don't do stack malloc in the
1760  // presence of inline asm on 32-bit platforms for the same reason.
1761  bool DoDynamicAlloca = ClDynamicAllocaStack && !HasNonEmptyInlineAsm;
1762  DoStackMalloc &= !HasNonEmptyInlineAsm || ASan.LongSize != 32;
1763
1764  Value *StaticAlloca =
1765      DoDynamicAlloca ? nullptr : createAllocaForLayout(IRB, L, false);
1766
1767  Value *FakeStack;
1768  Value *LocalStackBase;
1769
1770  if (DoStackMalloc) {
1771    // void *FakeStack = __asan_option_detect_stack_use_after_return
1772    //     ? __asan_stack_malloc_N(LocalStackSize)
1773    //     : nullptr;
1774    // void *LocalStackBase = (FakeStack) ? FakeStack : alloca(LocalStackSize);
1775    Constant *OptionDetectUAR = F.getParent()->getOrInsertGlobal(
1776        kAsanOptionDetectUAR, IRB.getInt32Ty());
1777    Value *UARIsEnabled =
1778        IRB.CreateICmpNE(IRB.CreateLoad(OptionDetectUAR),
1779                         Constant::getNullValue(IRB.getInt32Ty()));
1780    Instruction *Term =
1781        SplitBlockAndInsertIfThen(UARIsEnabled, InsBefore, false);
1782    IRBuilder<> IRBIf(Term);
1783    IRBIf.SetCurrentDebugLocation(EntryDebugLocation);
1784    StackMallocIdx = StackMallocSizeClass(LocalStackSize);
1785    assert(StackMallocIdx <= kMaxAsanStackMallocSizeClass);
1786    Value *FakeStackValue =
1787        IRBIf.CreateCall(AsanStackMallocFunc[StackMallocIdx],
1788                         ConstantInt::get(IntptrTy, LocalStackSize));
1789    IRB.SetInsertPoint(InsBefore);
1790    IRB.SetCurrentDebugLocation(EntryDebugLocation);
1791    FakeStack = createPHI(IRB, UARIsEnabled, FakeStackValue, Term,
1792                          ConstantInt::get(IntptrTy, 0));
1793
1794    Value *NoFakeStack =
1795        IRB.CreateICmpEQ(FakeStack, Constant::getNullValue(IntptrTy));
1796    Term = SplitBlockAndInsertIfThen(NoFakeStack, InsBefore, false);
1797    IRBIf.SetInsertPoint(Term);
1798    IRBIf.SetCurrentDebugLocation(EntryDebugLocation);
1799    Value *AllocaValue =
1800        DoDynamicAlloca ? createAllocaForLayout(IRBIf, L, true) : StaticAlloca;
1801    IRB.SetInsertPoint(InsBefore);
1802    IRB.SetCurrentDebugLocation(EntryDebugLocation);
1803    LocalStackBase = createPHI(IRB, NoFakeStack, AllocaValue, Term, FakeStack);
1804  } else {
1805    // void *FakeStack = nullptr;
1806    // void *LocalStackBase = alloca(LocalStackSize);
1807    FakeStack = ConstantInt::get(IntptrTy, 0);
1808    LocalStackBase =
1809        DoDynamicAlloca ? createAllocaForLayout(IRB, L, true) : StaticAlloca;
1810  }
1811
1812  // Insert poison calls for lifetime intrinsics for alloca.
1813  bool HavePoisonedAllocas = false;
1814  for (const auto &APC : AllocaPoisonCallVec) {
1815    assert(APC.InsBefore);
1816    assert(APC.AI);
1817    IRBuilder<> IRB(APC.InsBefore);
1818    poisonAlloca(APC.AI, APC.Size, IRB, APC.DoPoison);
1819    HavePoisonedAllocas |= APC.DoPoison;
1820  }
1821
1822  // Replace Alloca instructions with base+offset.
1823  for (const auto &Desc : SVD) {
1824    AllocaInst *AI = Desc.AI;
1825    Value *NewAllocaPtr = IRB.CreateIntToPtr(
1826        IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy, Desc.Offset)),
1827        AI->getType());
1828    replaceDbgDeclareForAlloca(AI, NewAllocaPtr, DIB, /*Deref=*/true);
1829    AI->replaceAllUsesWith(NewAllocaPtr);
1830  }
1831
1832  // The left-most redzone has enough space for at least 4 pointers.
1833  // Write the Magic value to redzone[0].
1834  Value *BasePlus0 = IRB.CreateIntToPtr(LocalStackBase, IntptrPtrTy);
1835  IRB.CreateStore(ConstantInt::get(IntptrTy, kCurrentStackFrameMagic),
1836                  BasePlus0);
1837  // Write the frame description constant to redzone[1].
1838  Value *BasePlus1 = IRB.CreateIntToPtr(
1839      IRB.CreateAdd(LocalStackBase,
1840                    ConstantInt::get(IntptrTy, ASan.LongSize / 8)),
1841      IntptrPtrTy);
1842  GlobalVariable *StackDescriptionGlobal =
1843      createPrivateGlobalForString(*F.getParent(), L.DescriptionString,
1844                                   /*AllowMerging*/ true);
1845  Value *Description = IRB.CreatePointerCast(StackDescriptionGlobal, IntptrTy);
1846  IRB.CreateStore(Description, BasePlus1);
1847  // Write the PC to redzone[2].
1848  Value *BasePlus2 = IRB.CreateIntToPtr(
1849      IRB.CreateAdd(LocalStackBase,
1850                    ConstantInt::get(IntptrTy, 2 * ASan.LongSize / 8)),
1851      IntptrPtrTy);
1852  IRB.CreateStore(IRB.CreatePointerCast(&F, IntptrTy), BasePlus2);
1853
1854  // Poison the stack redzones at the entry.
1855  Value *ShadowBase = ASan.memToShadow(LocalStackBase, IRB);
1856  poisonRedZones(L.ShadowBytes, IRB, ShadowBase, true);
1857
1858  // (Un)poison the stack before all ret instructions.
1859  for (auto Ret : RetVec) {
1860    IRBuilder<> IRBRet(Ret);
1861    // Mark the current frame as retired.
1862    IRBRet.CreateStore(ConstantInt::get(IntptrTy, kRetiredStackFrameMagic),
1863                       BasePlus0);
1864    if (DoStackMalloc) {
1865      assert(StackMallocIdx >= 0);
1866      // if FakeStack != 0  // LocalStackBase == FakeStack
1867      //     // In use-after-return mode, poison the whole stack frame.
1868      //     if StackMallocIdx <= 4
1869      //         // For small sizes inline the whole thing:
1870      //         memset(ShadowBase, kAsanStackAfterReturnMagic, ShadowSize);
1871      //         **SavedFlagPtr(FakeStack) = 0
1872      //     else
1873      //         __asan_stack_free_N(FakeStack, LocalStackSize)
1874      // else
1875      //     <This is not a fake stack; unpoison the redzones>
1876      Value *Cmp =
1877          IRBRet.CreateICmpNE(FakeStack, Constant::getNullValue(IntptrTy));
1878      TerminatorInst *ThenTerm, *ElseTerm;
1879      SplitBlockAndInsertIfThenElse(Cmp, Ret, &ThenTerm, &ElseTerm);
1880
1881      IRBuilder<> IRBPoison(ThenTerm);
1882      if (StackMallocIdx <= 4) {
1883        int ClassSize = kMinStackMallocSize << StackMallocIdx;
1884        SetShadowToStackAfterReturnInlined(IRBPoison, ShadowBase,
1885                                           ClassSize >> Mapping.Scale);
1886        Value *SavedFlagPtrPtr = IRBPoison.CreateAdd(
1887            FakeStack,
1888            ConstantInt::get(IntptrTy, ClassSize - ASan.LongSize / 8));
1889        Value *SavedFlagPtr = IRBPoison.CreateLoad(
1890            IRBPoison.CreateIntToPtr(SavedFlagPtrPtr, IntptrPtrTy));
1891        IRBPoison.CreateStore(
1892            Constant::getNullValue(IRBPoison.getInt8Ty()),
1893            IRBPoison.CreateIntToPtr(SavedFlagPtr, IRBPoison.getInt8PtrTy()));
1894      } else {
1895        // For larger frames call __asan_stack_free_*.
1896        IRBPoison.CreateCall2(AsanStackFreeFunc[StackMallocIdx], FakeStack,
1897                              ConstantInt::get(IntptrTy, LocalStackSize));
1898      }
1899
1900      IRBuilder<> IRBElse(ElseTerm);
1901      poisonRedZones(L.ShadowBytes, IRBElse, ShadowBase, false);
1902    } else if (HavePoisonedAllocas) {
1903      // If we poisoned some allocas in llvm.lifetime analysis,
1904      // unpoison whole stack frame now.
1905      poisonAlloca(LocalStackBase, LocalStackSize, IRBRet, false);
1906    } else {
1907      poisonRedZones(L.ShadowBytes, IRBRet, ShadowBase, false);
1908    }
1909  }
1910
1911  // We are done. Remove the old unused alloca instructions.
1912  for (auto AI : AllocaVec) AI->eraseFromParent();
1913}
1914
1915void FunctionStackPoisoner::poisonAlloca(Value *V, uint64_t Size,
1916                                         IRBuilder<> &IRB, bool DoPoison) {
1917  // For now just insert the call to ASan runtime.
1918  Value *AddrArg = IRB.CreatePointerCast(V, IntptrTy);
1919  Value *SizeArg = ConstantInt::get(IntptrTy, Size);
1920  IRB.CreateCall2(
1921      DoPoison ? AsanPoisonStackMemoryFunc : AsanUnpoisonStackMemoryFunc,
1922      AddrArg, SizeArg);
1923}
1924
1925// Handling llvm.lifetime intrinsics for a given %alloca:
1926// (1) collect all llvm.lifetime.xxx(%size, %value) describing the alloca.
1927// (2) if %size is constant, poison memory for llvm.lifetime.end (to detect
1928//     invalid accesses) and unpoison it for llvm.lifetime.start (the memory
1929//     could be poisoned by previous llvm.lifetime.end instruction, as the
1930//     variable may go in and out of scope several times, e.g. in loops).
1931// (3) if we poisoned at least one %alloca in a function,
1932//     unpoison the whole stack frame at function exit.
1933
1934AllocaInst *FunctionStackPoisoner::findAllocaForValue(Value *V) {
1935  if (AllocaInst *AI = dyn_cast<AllocaInst>(V))
1936    // We're intested only in allocas we can handle.
1937    return ASan.isInterestingAlloca(*AI) ? AI : nullptr;
1938  // See if we've already calculated (or started to calculate) alloca for a
1939  // given value.
1940  AllocaForValueMapTy::iterator I = AllocaForValue.find(V);
1941  if (I != AllocaForValue.end()) return I->second;
1942  // Store 0 while we're calculating alloca for value V to avoid
1943  // infinite recursion if the value references itself.
1944  AllocaForValue[V] = nullptr;
1945  AllocaInst *Res = nullptr;
1946  if (CastInst *CI = dyn_cast<CastInst>(V))
1947    Res = findAllocaForValue(CI->getOperand(0));
1948  else if (PHINode *PN = dyn_cast<PHINode>(V)) {
1949    for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
1950      Value *IncValue = PN->getIncomingValue(i);
1951      // Allow self-referencing phi-nodes.
1952      if (IncValue == PN) continue;
1953      AllocaInst *IncValueAI = findAllocaForValue(IncValue);
1954      // AI for incoming values should exist and should all be equal.
1955      if (IncValueAI == nullptr || (Res != nullptr && IncValueAI != Res))
1956        return nullptr;
1957      Res = IncValueAI;
1958    }
1959  }
1960  if (Res) AllocaForValue[V] = Res;
1961  return Res;
1962}
1963
1964// Compute PartialRzMagic for dynamic alloca call. PartialRzMagic is
1965// constructed from two separate 32-bit numbers: PartialRzMagic = Val1 | Val2.
1966// (1) Val1 is resposible for forming base value for PartialRzMagic, containing
1967//     only 00 for fully addressable and 0xcb for fully poisoned bytes for each
1968//     8-byte chunk of user memory respectively.
1969// (2) Val2 forms the value for marking first poisoned byte in shadow memory
1970//     with appropriate value (0x01 - 0x07 or 0xcb if Padding % 8 == 0).
1971
1972// Shift = Padding & ~7; // the number of bits we need to shift to access first
1973//                          chunk in shadow memory, containing nonzero bytes.
1974// Example:
1975// Padding = 21                       Padding = 16
1976// Shadow:  |00|00|05|cb|          Shadow:  |00|00|cb|cb|
1977//                ^                               ^
1978//                |                               |
1979// Shift = 21 & ~7 = 16            Shift = 16 & ~7 = 16
1980//
1981// Val1 = 0xcbcbcbcb << Shift;
1982// PartialBits = Padding ? Padding & 7 : 0xcb;
1983// Val2 = PartialBits << Shift;
1984// Result = Val1 | Val2;
1985Value *FunctionStackPoisoner::computePartialRzMagic(Value *PartialSize,
1986                                                    IRBuilder<> &IRB) {
1987  PartialSize = IRB.CreateIntCast(PartialSize, IRB.getInt32Ty(), false);
1988  Value *Shift = IRB.CreateAnd(PartialSize, IRB.getInt32(~7));
1989  unsigned Val1Int = kAsanAllocaPartialVal1;
1990  unsigned Val2Int = kAsanAllocaPartialVal2;
1991  if (!F.getParent()->getDataLayout().isLittleEndian()) {
1992    Val1Int = sys::getSwappedBytes(Val1Int);
1993    Val2Int = sys::getSwappedBytes(Val2Int);
1994  }
1995  Value *Val1 = shiftAllocaMagic(IRB.getInt32(Val1Int), IRB, Shift);
1996  Value *PartialBits = IRB.CreateAnd(PartialSize, IRB.getInt32(7));
1997  // For BigEndian get 0x000000YZ -> 0xYZ000000.
1998  if (F.getParent()->getDataLayout().isBigEndian())
1999    PartialBits = IRB.CreateShl(PartialBits, IRB.getInt32(24));
2000  Value *Val2 = IRB.getInt32(Val2Int);
2001  Value *Cond =
2002      IRB.CreateICmpNE(PartialBits, Constant::getNullValue(IRB.getInt32Ty()));
2003  Val2 = IRB.CreateSelect(Cond, shiftAllocaMagic(PartialBits, IRB, Shift),
2004                          shiftAllocaMagic(Val2, IRB, Shift));
2005  return IRB.CreateOr(Val1, Val2);
2006}
2007
2008void FunctionStackPoisoner::handleDynamicAllocaCall(
2009    DynamicAllocaCall &AllocaCall) {
2010  AllocaInst *AI = AllocaCall.AI;
2011  if (!doesDominateAllExits(AI)) {
2012    // We do not yet handle complex allocas
2013    AllocaCall.Poison = false;
2014    return;
2015  }
2016
2017  IRBuilder<> IRB(AI);
2018
2019  PointerType *Int32PtrTy = PointerType::getUnqual(IRB.getInt32Ty());
2020  const unsigned Align = std::max(kAllocaRzSize, AI->getAlignment());
2021  const uint64_t AllocaRedzoneMask = kAllocaRzSize - 1;
2022
2023  Value *Zero = Constant::getNullValue(IntptrTy);
2024  Value *AllocaRzSize = ConstantInt::get(IntptrTy, kAllocaRzSize);
2025  Value *AllocaRzMask = ConstantInt::get(IntptrTy, AllocaRedzoneMask);
2026  Value *NotAllocaRzMask = ConstantInt::get(IntptrTy, ~AllocaRedzoneMask);
2027
2028  // Since we need to extend alloca with additional memory to locate
2029  // redzones, and OldSize is number of allocated blocks with
2030  // ElementSize size, get allocated memory size in bytes by
2031  // OldSize * ElementSize.
2032  unsigned ElementSize =
2033      F.getParent()->getDataLayout().getTypeAllocSize(AI->getAllocatedType());
2034  Value *OldSize = IRB.CreateMul(AI->getArraySize(),
2035                                 ConstantInt::get(IntptrTy, ElementSize));
2036
2037  // PartialSize = OldSize % 32
2038  Value *PartialSize = IRB.CreateAnd(OldSize, AllocaRzMask);
2039
2040  // Misalign = kAllocaRzSize - PartialSize;
2041  Value *Misalign = IRB.CreateSub(AllocaRzSize, PartialSize);
2042
2043  // PartialPadding = Misalign != kAllocaRzSize ? Misalign : 0;
2044  Value *Cond = IRB.CreateICmpNE(Misalign, AllocaRzSize);
2045  Value *PartialPadding = IRB.CreateSelect(Cond, Misalign, Zero);
2046
2047  // AdditionalChunkSize = Align + PartialPadding + kAllocaRzSize
2048  // Align is added to locate left redzone, PartialPadding for possible
2049  // partial redzone and kAllocaRzSize for right redzone respectively.
2050  Value *AdditionalChunkSize = IRB.CreateAdd(
2051      ConstantInt::get(IntptrTy, Align + kAllocaRzSize), PartialPadding);
2052
2053  Value *NewSize = IRB.CreateAdd(OldSize, AdditionalChunkSize);
2054
2055  // Insert new alloca with new NewSize and Align params.
2056  AllocaInst *NewAlloca = IRB.CreateAlloca(IRB.getInt8Ty(), NewSize);
2057  NewAlloca->setAlignment(Align);
2058
2059  // NewAddress = Address + Align
2060  Value *NewAddress = IRB.CreateAdd(IRB.CreatePtrToInt(NewAlloca, IntptrTy),
2061                                    ConstantInt::get(IntptrTy, Align));
2062
2063  Value *NewAddressPtr = IRB.CreateIntToPtr(NewAddress, AI->getType());
2064
2065  // LeftRzAddress = NewAddress - kAllocaRzSize
2066  Value *LeftRzAddress = IRB.CreateSub(NewAddress, AllocaRzSize);
2067
2068  // Poisoning left redzone.
2069  AllocaCall.LeftRzAddr = ASan.memToShadow(LeftRzAddress, IRB);
2070  IRB.CreateStore(ConstantInt::get(IRB.getInt32Ty(), kAsanAllocaLeftMagic),
2071                  IRB.CreateIntToPtr(AllocaCall.LeftRzAddr, Int32PtrTy));
2072
2073  // PartialRzAligned = PartialRzAddr & ~AllocaRzMask
2074  Value *PartialRzAddr = IRB.CreateAdd(NewAddress, OldSize);
2075  Value *PartialRzAligned = IRB.CreateAnd(PartialRzAddr, NotAllocaRzMask);
2076
2077  // Poisoning partial redzone.
2078  Value *PartialRzMagic = computePartialRzMagic(PartialSize, IRB);
2079  Value *PartialRzShadowAddr = ASan.memToShadow(PartialRzAligned, IRB);
2080  IRB.CreateStore(PartialRzMagic,
2081                  IRB.CreateIntToPtr(PartialRzShadowAddr, Int32PtrTy));
2082
2083  // RightRzAddress
2084  //   =  (PartialRzAddr + AllocaRzMask) & ~AllocaRzMask
2085  Value *RightRzAddress = IRB.CreateAnd(
2086      IRB.CreateAdd(PartialRzAddr, AllocaRzMask), NotAllocaRzMask);
2087
2088  // Poisoning right redzone.
2089  AllocaCall.RightRzAddr = ASan.memToShadow(RightRzAddress, IRB);
2090  IRB.CreateStore(ConstantInt::get(IRB.getInt32Ty(), kAsanAllocaRightMagic),
2091                  IRB.CreateIntToPtr(AllocaCall.RightRzAddr, Int32PtrTy));
2092
2093  // Replace all uses of AddessReturnedByAlloca with NewAddress.
2094  AI->replaceAllUsesWith(NewAddressPtr);
2095
2096  // We are done. Erase old alloca and store left, partial and right redzones
2097  // shadow addresses for future unpoisoning.
2098  AI->eraseFromParent();
2099  NumInstrumentedDynamicAllocas++;
2100}
2101
2102// isSafeAccess returns true if Addr is always inbounds with respect to its
2103// base object. For example, it is a field access or an array access with
2104// constant inbounds index.
2105bool AddressSanitizer::isSafeAccess(ObjectSizeOffsetVisitor &ObjSizeVis,
2106                                    Value *Addr, uint64_t TypeSize) const {
2107  SizeOffsetType SizeOffset = ObjSizeVis.compute(Addr);
2108  if (!ObjSizeVis.bothKnown(SizeOffset)) return false;
2109  uint64_t Size = SizeOffset.first.getZExtValue();
2110  int64_t Offset = SizeOffset.second.getSExtValue();
2111  // Three checks are required to ensure safety:
2112  // . Offset >= 0  (since the offset is given from the base ptr)
2113  // . Size >= Offset  (unsigned)
2114  // . Size - Offset >= NeededSize  (unsigned)
2115  return Offset >= 0 && Size >= uint64_t(Offset) &&
2116         Size - uint64_t(Offset) >= TypeSize / 8;
2117}
2118