AddressSanitizer.cpp revision 3016056769639878b4f152838f0cf16d2e482339 
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#define DEBUG_TYPE "asan"
17
18#include "llvm/Transforms/Instrumentation.h"
19#include "llvm/ADT/ArrayRef.h"
20#include "llvm/ADT/DenseMap.h"
21#include "llvm/ADT/DepthFirstIterator.h"
22#include "llvm/ADT/OwningPtr.h"
23#include "llvm/ADT/SmallSet.h"
24#include "llvm/ADT/SmallString.h"
25#include "llvm/ADT/SmallVector.h"
26#include "llvm/ADT/StringExtras.h"
27#include "llvm/ADT/Triple.h"
28#include "llvm/DIBuilder.h"
29#include "llvm/IR/DataLayout.h"
30#include "llvm/IR/Function.h"
31#include "llvm/IR/IRBuilder.h"
32#include "llvm/IR/InlineAsm.h"
33#include "llvm/IR/IntrinsicInst.h"
34#include "llvm/IR/LLVMContext.h"
35#include "llvm/IR/Module.h"
36#include "llvm/IR/Type.h"
37#include "llvm/InstVisitor.h"
38#include "llvm/Support/CallSite.h"
39#include "llvm/Support/CommandLine.h"
40#include "llvm/Support/DataTypes.h"
41#include "llvm/Support/Debug.h"
42#include "llvm/Support/raw_ostream.h"
43#include "llvm/Support/system_error.h"
44#include "llvm/Target/TargetMachine.h"
45#include "llvm/Transforms/Utils/BasicBlockUtils.h"
46#include "llvm/Transforms/Utils/BlackList.h"
47#include "llvm/Transforms/Utils/Local.h"
48#include "llvm/Transforms/Utils/ModuleUtils.h"
49#include <algorithm>
50#include <string>
51
52using namespace llvm;
53
54static const uint64_t kDefaultShadowScale = 3;
55static const uint64_t kDefaultShadowOffset32 = 1ULL << 29;
56static const uint64_t kDefaultShadowOffset64 = 1ULL << 44;
57static const uint64_t kDefaultShort64bitShadowOffset = 0x7FFF8000;  // < 2G.
58static const uint64_t kPPC64_ShadowOffset64 = 1ULL << 41;
59
60static const size_t kMaxStackMallocSize = 1 << 16;  // 64K
61static const uintptr_t kCurrentStackFrameMagic = 0x41B58AB3;
62static const uintptr_t kRetiredStackFrameMagic = 0x45E0360E;
63
64static const char *kAsanModuleCtorName = "asan.module_ctor";
65static const char *kAsanModuleDtorName = "asan.module_dtor";
66static const int   kAsanCtorAndCtorPriority = 1;
67static const char *kAsanReportErrorTemplate = "__asan_report_";
68static const char *kAsanReportLoadN = "__asan_report_load_n";
69static const char *kAsanReportStoreN = "__asan_report_store_n";
70static const char *kAsanRegisterGlobalsName = "__asan_register_globals";
71static const char *kAsanUnregisterGlobalsName = "__asan_unregister_globals";
72static const char *kAsanPoisonGlobalsName = "__asan_before_dynamic_init";
73static const char *kAsanUnpoisonGlobalsName = "__asan_after_dynamic_init";
74static const char *kAsanInitName = "__asan_init_v3";
75static const char *kAsanHandleNoReturnName = "__asan_handle_no_return";
76static const char *kAsanMappingOffsetName = "__asan_mapping_offset";
77static const char *kAsanMappingScaleName = "__asan_mapping_scale";
78static const char *kAsanStackMallocName = "__asan_stack_malloc";
79static const char *kAsanStackFreeName = "__asan_stack_free";
80static const char *kAsanGenPrefix = "__asan_gen_";
81static const char *kAsanPoisonStackMemoryName = "__asan_poison_stack_memory";
82static const char *kAsanUnpoisonStackMemoryName =
83    "__asan_unpoison_stack_memory";
84
85static const int kAsanStackLeftRedzoneMagic = 0xf1;
86static const int kAsanStackMidRedzoneMagic = 0xf2;
87static const int kAsanStackRightRedzoneMagic = 0xf3;
88static const int kAsanStackPartialRedzoneMagic = 0xf4;
89
90// Accesses sizes are powers of two: 1, 2, 4, 8, 16.
91static const size_t kNumberOfAccessSizes = 5;
92
93// Command-line flags.
94
95// This flag may need to be replaced with -f[no-]asan-reads.
96static cl::opt<bool> ClInstrumentReads("asan-instrument-reads",
97       cl::desc("instrument read instructions"), cl::Hidden, cl::init(true));
98static cl::opt<bool> ClInstrumentWrites("asan-instrument-writes",
99       cl::desc("instrument write instructions"), cl::Hidden, cl::init(true));
100static cl::opt<bool> ClInstrumentAtomics("asan-instrument-atomics",
101       cl::desc("instrument atomic instructions (rmw, cmpxchg)"),
102       cl::Hidden, cl::init(true));
103static cl::opt<bool> ClAlwaysSlowPath("asan-always-slow-path",
104       cl::desc("use instrumentation with slow path for all accesses"),
105       cl::Hidden, cl::init(false));
106// This flag limits the number of instructions to be instrumented
107// in any given BB. Normally, this should be set to unlimited (INT_MAX),
108// but due to http://llvm.org/bugs/show_bug.cgi?id=12652 we temporary
109// set it to 10000.
110static cl::opt<int> ClMaxInsnsToInstrumentPerBB("asan-max-ins-per-bb",
111       cl::init(10000),
112       cl::desc("maximal number of instructions to instrument in any given BB"),
113       cl::Hidden);
114// This flag may need to be replaced with -f[no]asan-stack.
115static cl::opt<bool> ClStack("asan-stack",
116       cl::desc("Handle stack memory"), cl::Hidden, cl::init(true));
117// This flag may need to be replaced with -f[no]asan-use-after-return.
118static cl::opt<bool> ClUseAfterReturn("asan-use-after-return",
119       cl::desc("Check return-after-free"), cl::Hidden, cl::init(false));
120// This flag may need to be replaced with -f[no]asan-globals.
121static cl::opt<bool> ClGlobals("asan-globals",
122       cl::desc("Handle global objects"), cl::Hidden, cl::init(true));
123static cl::opt<bool> ClInitializers("asan-initialization-order",
124       cl::desc("Handle C++ initializer order"), cl::Hidden, cl::init(false));
125static cl::opt<bool> ClMemIntrin("asan-memintrin",
126       cl::desc("Handle memset/memcpy/memmove"), cl::Hidden, cl::init(true));
127static cl::opt<bool> ClRealignStack("asan-realign-stack",
128       cl::desc("Realign stack to 32"), cl::Hidden, cl::init(true));
129static cl::opt<std::string> ClBlacklistFile("asan-blacklist",
130       cl::desc("File containing the list of objects to ignore "
131                "during instrumentation"), cl::Hidden);
132
133// These flags allow to change the shadow mapping.
134// The shadow mapping looks like
135//    Shadow = (Mem >> scale) + (1 << offset_log)
136static cl::opt<int> ClMappingScale("asan-mapping-scale",
137       cl::desc("scale of asan shadow mapping"), cl::Hidden, cl::init(0));
138static cl::opt<int> ClMappingOffsetLog("asan-mapping-offset-log",
139       cl::desc("offset of asan shadow mapping"), cl::Hidden, cl::init(-1));
140static cl::opt<bool> ClShort64BitOffset("asan-short-64bit-mapping-offset",
141       cl::desc("Use short immediate constant as the mapping offset for 64bit"),
142       cl::Hidden, cl::init(true));
143
144// Optimization flags. Not user visible, used mostly for testing
145// and benchmarking the tool.
146static cl::opt<bool> ClOpt("asan-opt",
147       cl::desc("Optimize instrumentation"), cl::Hidden, cl::init(true));
148static cl::opt<bool> ClOptSameTemp("asan-opt-same-temp",
149       cl::desc("Instrument the same temp just once"), cl::Hidden,
150       cl::init(true));
151static cl::opt<bool> ClOptGlobals("asan-opt-globals",
152       cl::desc("Don't instrument scalar globals"), cl::Hidden, cl::init(true));
153
154static cl::opt<bool> ClCheckLifetime("asan-check-lifetime",
155       cl::desc("Use llvm.lifetime intrinsics to insert extra checks"),
156       cl::Hidden, cl::init(false));
157
158// Debug flags.
159static cl::opt<int> ClDebug("asan-debug", cl::desc("debug"), cl::Hidden,
160                            cl::init(0));
161static cl::opt<int> ClDebugStack("asan-debug-stack", cl::desc("debug stack"),
162                                 cl::Hidden, cl::init(0));
163static cl::opt<std::string> ClDebugFunc("asan-debug-func",
164                                        cl::Hidden, cl::desc("Debug func"));
165static cl::opt<int> ClDebugMin("asan-debug-min", cl::desc("Debug min inst"),
166                               cl::Hidden, cl::init(-1));
167static cl::opt<int> ClDebugMax("asan-debug-max", cl::desc("Debug man inst"),
168                               cl::Hidden, cl::init(-1));
169
170namespace {
171/// A set of dynamically initialized globals extracted from metadata.
172class SetOfDynamicallyInitializedGlobals {
173 public:
174  void Init(Module& M) {
175    // Clang generates metadata identifying all dynamically initialized globals.
176    NamedMDNode *DynamicGlobals =
177        M.getNamedMetadata("llvm.asan.dynamically_initialized_globals");
178    if (!DynamicGlobals)
179      return;
180    for (int i = 0, n = DynamicGlobals->getNumOperands(); i < n; ++i) {
181      MDNode *MDN = DynamicGlobals->getOperand(i);
182      assert(MDN->getNumOperands() == 1);
183      Value *VG = MDN->getOperand(0);
184      // The optimizer may optimize away a global entirely, in which case we
185      // cannot instrument access to it.
186      if (!VG)
187        continue;
188      DynInitGlobals.insert(cast<GlobalVariable>(VG));
189    }
190  }
191  bool Contains(GlobalVariable *G) { return DynInitGlobals.count(G) != 0; }
192 private:
193  SmallSet<GlobalValue*, 32> DynInitGlobals;
194};
195
196/// This struct defines the shadow mapping using the rule:
197///   shadow = (mem >> Scale) ADD-or-OR Offset.
198struct ShadowMapping {
199  int Scale;
200  uint64_t Offset;
201  bool OrShadowOffset;
202};
203
204static ShadowMapping getShadowMapping(const Module &M, int LongSize,
205                                      bool ZeroBaseShadow) {
206  llvm::Triple TargetTriple(M.getTargetTriple());
207  bool IsAndroid = TargetTriple.getEnvironment() == llvm::Triple::Android;
208  bool IsMacOSX = TargetTriple.getOS() == llvm::Triple::MacOSX;
209  bool IsPPC64 = TargetTriple.getArch() == llvm::Triple::ppc64;
210  bool IsX86_64 = TargetTriple.getArch() == llvm::Triple::x86_64;
211
212  ShadowMapping Mapping;
213
214  // OR-ing shadow offset if more efficient (at least on x86),
215  // but on ppc64 we have to use add since the shadow offset is not neccesary
216  // 1/8-th of the address space.
217  Mapping.OrShadowOffset = !IsPPC64 && !ClShort64BitOffset;
218
219  Mapping.Offset = (IsAndroid || ZeroBaseShadow) ? 0 :
220      (LongSize == 32 ? kDefaultShadowOffset32 :
221       IsPPC64 ? kPPC64_ShadowOffset64 : kDefaultShadowOffset64);
222  if (!ZeroBaseShadow && ClShort64BitOffset && IsX86_64 && !IsMacOSX) {
223    assert(LongSize == 64);
224    Mapping.Offset = kDefaultShort64bitShadowOffset;
225  }
226  if (!ZeroBaseShadow && ClMappingOffsetLog >= 0) {
227    // Zero offset log is the special case.
228    Mapping.Offset = (ClMappingOffsetLog == 0) ? 0 : 1ULL << ClMappingOffsetLog;
229  }
230
231  Mapping.Scale = kDefaultShadowScale;
232  if (ClMappingScale) {
233    Mapping.Scale = ClMappingScale;
234  }
235
236  return Mapping;
237}
238
239static size_t RedzoneSizeForScale(int MappingScale) {
240  // Redzone used for stack and globals is at least 32 bytes.
241  // For scales 6 and 7, the redzone has to be 64 and 128 bytes respectively.
242  return std::max(32U, 1U << MappingScale);
243}
244
245/// AddressSanitizer: instrument the code in module to find memory bugs.
246struct AddressSanitizer : public FunctionPass {
247  AddressSanitizer(bool CheckInitOrder = true,
248                   bool CheckUseAfterReturn = false,
249                   bool CheckLifetime = false,
250                   StringRef BlacklistFile = StringRef(),
251                   bool ZeroBaseShadow = false)
252      : FunctionPass(ID),
253        CheckInitOrder(CheckInitOrder || ClInitializers),
254        CheckUseAfterReturn(CheckUseAfterReturn || ClUseAfterReturn),
255        CheckLifetime(CheckLifetime || ClCheckLifetime),
256        BlacklistFile(BlacklistFile.empty() ? ClBlacklistFile
257                                            : BlacklistFile),
258        ZeroBaseShadow(ZeroBaseShadow) {}
259  virtual const char *getPassName() const {
260    return "AddressSanitizerFunctionPass";
261  }
262  void instrumentMop(Instruction *I);
263  void instrumentAddress(Instruction *OrigIns, Instruction *InsertBefore,
264                         Value *Addr, uint32_t TypeSize, bool IsWrite,
265                         Value *SizeArgument);
266  Value *createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
267                           Value *ShadowValue, uint32_t TypeSize);
268  Instruction *generateCrashCode(Instruction *InsertBefore, Value *Addr,
269                                 bool IsWrite, size_t AccessSizeIndex,
270                                 Value *SizeArgument);
271  bool instrumentMemIntrinsic(MemIntrinsic *MI);
272  void instrumentMemIntrinsicParam(Instruction *OrigIns, Value *Addr,
273                                   Value *Size,
274                                   Instruction *InsertBefore, bool IsWrite);
275  Value *memToShadow(Value *Shadow, IRBuilder<> &IRB);
276  bool runOnFunction(Function &F);
277  void createInitializerPoisonCalls(Module &M,
278                                    Value *FirstAddr, Value *LastAddr);
279  bool maybeInsertAsanInitAtFunctionEntry(Function &F);
280  void emitShadowMapping(Module &M, IRBuilder<> &IRB) const;
281  virtual bool doInitialization(Module &M);
282  static char ID;  // Pass identification, replacement for typeid
283
284 private:
285  void initializeCallbacks(Module &M);
286
287  bool ShouldInstrumentGlobal(GlobalVariable *G);
288  bool LooksLikeCodeInBug11395(Instruction *I);
289  void FindDynamicInitializers(Module &M);
290
291  bool CheckInitOrder;
292  bool CheckUseAfterReturn;
293  bool CheckLifetime;
294  SmallString<64> BlacklistFile;
295  bool ZeroBaseShadow;
296
297  LLVMContext *C;
298  DataLayout *TD;
299  int LongSize;
300  Type *IntptrTy;
301  ShadowMapping Mapping;
302  Function *AsanCtorFunction;
303  Function *AsanInitFunction;
304  Function *AsanHandleNoReturnFunc;
305  OwningPtr<BlackList> BL;
306  // This array is indexed by AccessIsWrite and log2(AccessSize).
307  Function *AsanErrorCallback[2][kNumberOfAccessSizes];
308  // This array is indexed by AccessIsWrite.
309  Function *AsanErrorCallbackSized[2];
310  InlineAsm *EmptyAsm;
311  SetOfDynamicallyInitializedGlobals DynamicallyInitializedGlobals;
312
313  friend struct FunctionStackPoisoner;
314};
315
316class AddressSanitizerModule : public ModulePass {
317 public:
318  AddressSanitizerModule(bool CheckInitOrder = true,
319                         StringRef BlacklistFile = StringRef(),
320                         bool ZeroBaseShadow = false)
321      : ModulePass(ID),
322        CheckInitOrder(CheckInitOrder || ClInitializers),
323        BlacklistFile(BlacklistFile.empty() ? ClBlacklistFile
324                                            : BlacklistFile),
325        ZeroBaseShadow(ZeroBaseShadow) {}
326  bool runOnModule(Module &M);
327  static char ID;  // Pass identification, replacement for typeid
328  virtual const char *getPassName() const {
329    return "AddressSanitizerModule";
330  }
331
332 private:
333  void initializeCallbacks(Module &M);
334
335  bool ShouldInstrumentGlobal(GlobalVariable *G);
336  void createInitializerPoisonCalls(Module &M, Value *FirstAddr,
337                                    Value *LastAddr);
338  size_t RedzoneSize() const {
339    return RedzoneSizeForScale(Mapping.Scale);
340  }
341
342  bool CheckInitOrder;
343  SmallString<64> BlacklistFile;
344  bool ZeroBaseShadow;
345
346  OwningPtr<BlackList> BL;
347  SetOfDynamicallyInitializedGlobals DynamicallyInitializedGlobals;
348  Type *IntptrTy;
349  LLVMContext *C;
350  DataLayout *TD;
351  ShadowMapping Mapping;
352  Function *AsanPoisonGlobals;
353  Function *AsanUnpoisonGlobals;
354  Function *AsanRegisterGlobals;
355  Function *AsanUnregisterGlobals;
356};
357
358// Stack poisoning does not play well with exception handling.
359// When an exception is thrown, we essentially bypass the code
360// that unpoisones the stack. This is why the run-time library has
361// to intercept __cxa_throw (as well as longjmp, etc) and unpoison the entire
362// stack in the interceptor. This however does not work inside the
363// actual function which catches the exception. Most likely because the
364// compiler hoists the load of the shadow value somewhere too high.
365// This causes asan to report a non-existing bug on 453.povray.
366// It sounds like an LLVM bug.
367struct FunctionStackPoisoner : public InstVisitor<FunctionStackPoisoner> {
368  Function &F;
369  AddressSanitizer &ASan;
370  DIBuilder DIB;
371  LLVMContext *C;
372  Type *IntptrTy;
373  Type *IntptrPtrTy;
374  ShadowMapping Mapping;
375
376  SmallVector<AllocaInst*, 16> AllocaVec;
377  SmallVector<Instruction*, 8> RetVec;
378  uint64_t TotalStackSize;
379  unsigned StackAlignment;
380
381  Function *AsanStackMallocFunc, *AsanStackFreeFunc;
382  Function *AsanPoisonStackMemoryFunc, *AsanUnpoisonStackMemoryFunc;
383
384  // Stores a place and arguments of poisoning/unpoisoning call for alloca.
385  struct AllocaPoisonCall {
386    IntrinsicInst *InsBefore;
387    uint64_t Size;
388    bool DoPoison;
389  };
390  SmallVector<AllocaPoisonCall, 8> AllocaPoisonCallVec;
391
392  // Maps Value to an AllocaInst from which the Value is originated.
393  typedef DenseMap<Value*, AllocaInst*> AllocaForValueMapTy;
394  AllocaForValueMapTy AllocaForValue;
395
396  FunctionStackPoisoner(Function &F, AddressSanitizer &ASan)
397      : F(F), ASan(ASan), DIB(*F.getParent()), C(ASan.C),
398        IntptrTy(ASan.IntptrTy), IntptrPtrTy(PointerType::get(IntptrTy, 0)),
399        Mapping(ASan.Mapping),
400        TotalStackSize(0), StackAlignment(1 << Mapping.Scale) {}
401
402  bool runOnFunction() {
403    if (!ClStack) return false;
404    // Collect alloca, ret, lifetime instructions etc.
405    for (df_iterator<BasicBlock*> DI = df_begin(&F.getEntryBlock()),
406         DE = df_end(&F.getEntryBlock()); DI != DE; ++DI) {
407      BasicBlock *BB = *DI;
408      visit(*BB);
409    }
410    if (AllocaVec.empty()) return false;
411
412    initializeCallbacks(*F.getParent());
413
414    poisonStack();
415
416    if (ClDebugStack) {
417      DEBUG(dbgs() << F);
418    }
419    return true;
420  }
421
422  // Finds all static Alloca instructions and puts
423  // poisoned red zones around all of them.
424  // Then unpoison everything back before the function returns.
425  void poisonStack();
426
427  // ----------------------- Visitors.
428  /// \brief Collect all Ret instructions.
429  void visitReturnInst(ReturnInst &RI) {
430    RetVec.push_back(&RI);
431  }
432
433  /// \brief Collect Alloca instructions we want (and can) handle.
434  void visitAllocaInst(AllocaInst &AI) {
435    if (!isInterestingAlloca(AI)) return;
436
437    StackAlignment = std::max(StackAlignment, AI.getAlignment());
438    AllocaVec.push_back(&AI);
439    uint64_t AlignedSize =  getAlignedAllocaSize(&AI);
440    TotalStackSize += AlignedSize;
441  }
442
443  /// \brief Collect lifetime intrinsic calls to check for use-after-scope
444  /// errors.
445  void visitIntrinsicInst(IntrinsicInst &II) {
446    if (!ASan.CheckLifetime) return;
447    Intrinsic::ID ID = II.getIntrinsicID();
448    if (ID != Intrinsic::lifetime_start &&
449        ID != Intrinsic::lifetime_end)
450      return;
451    // Found lifetime intrinsic, add ASan instrumentation if necessary.
452    ConstantInt *Size = dyn_cast<ConstantInt>(II.getArgOperand(0));
453    // If size argument is undefined, don't do anything.
454    if (Size->isMinusOne()) return;
455    // Check that size doesn't saturate uint64_t and can
456    // be stored in IntptrTy.
457    const uint64_t SizeValue = Size->getValue().getLimitedValue();
458    if (SizeValue == ~0ULL ||
459        !ConstantInt::isValueValidForType(IntptrTy, SizeValue))
460      return;
461    // Find alloca instruction that corresponds to llvm.lifetime argument.
462    AllocaInst *AI = findAllocaForValue(II.getArgOperand(1));
463    if (!AI) return;
464    bool DoPoison = (ID == Intrinsic::lifetime_end);
465    AllocaPoisonCall APC = {&II, SizeValue, DoPoison};
466    AllocaPoisonCallVec.push_back(APC);
467  }
468
469  // ---------------------- Helpers.
470  void initializeCallbacks(Module &M);
471
472  // Check if we want (and can) handle this alloca.
473  bool isInterestingAlloca(AllocaInst &AI) {
474    return (!AI.isArrayAllocation() &&
475            AI.isStaticAlloca() &&
476            AI.getAllocatedType()->isSized());
477  }
478
479  size_t RedzoneSize() const {
480    return RedzoneSizeForScale(Mapping.Scale);
481  }
482  uint64_t getAllocaSizeInBytes(AllocaInst *AI) {
483    Type *Ty = AI->getAllocatedType();
484    uint64_t SizeInBytes = ASan.TD->getTypeAllocSize(Ty);
485    return SizeInBytes;
486  }
487  uint64_t getAlignedSize(uint64_t SizeInBytes) {
488    size_t RZ = RedzoneSize();
489    return ((SizeInBytes + RZ - 1) / RZ) * RZ;
490  }
491  uint64_t getAlignedAllocaSize(AllocaInst *AI) {
492    uint64_t SizeInBytes = getAllocaSizeInBytes(AI);
493    return getAlignedSize(SizeInBytes);
494  }
495  /// Finds alloca where the value comes from.
496  AllocaInst *findAllocaForValue(Value *V);
497  void poisonRedZones(const ArrayRef<AllocaInst*> &AllocaVec, IRBuilder<> IRB,
498                      Value *ShadowBase, bool DoPoison);
499  void poisonAlloca(Value *V, uint64_t Size, IRBuilder<> IRB, bool DoPoison);
500};
501
502}  // namespace
503
504char AddressSanitizer::ID = 0;
505INITIALIZE_PASS(AddressSanitizer, "asan",
506    "AddressSanitizer: detects use-after-free and out-of-bounds bugs.",
507    false, false)
508FunctionPass *llvm::createAddressSanitizerFunctionPass(
509    bool CheckInitOrder, bool CheckUseAfterReturn, bool CheckLifetime,
510    StringRef BlacklistFile, bool ZeroBaseShadow) {
511  return new AddressSanitizer(CheckInitOrder, CheckUseAfterReturn,
512                              CheckLifetime, BlacklistFile, ZeroBaseShadow);
513}
514
515char AddressSanitizerModule::ID = 0;
516INITIALIZE_PASS(AddressSanitizerModule, "asan-module",
517    "AddressSanitizer: detects use-after-free and out-of-bounds bugs."
518    "ModulePass", false, false)
519ModulePass *llvm::createAddressSanitizerModulePass(
520    bool CheckInitOrder, StringRef BlacklistFile, bool ZeroBaseShadow) {
521  return new AddressSanitizerModule(CheckInitOrder, BlacklistFile,
522                                    ZeroBaseShadow);
523}
524
525static size_t TypeSizeToSizeIndex(uint32_t TypeSize) {
526  size_t Res = CountTrailingZeros_32(TypeSize / 8);
527  assert(Res < kNumberOfAccessSizes);
528  return Res;
529}
530
531// Create a constant for Str so that we can pass it to the run-time lib.
532static GlobalVariable *createPrivateGlobalForString(Module &M, StringRef Str) {
533  Constant *StrConst = ConstantDataArray::getString(M.getContext(), Str);
534  GlobalVariable *GV = new GlobalVariable(M, StrConst->getType(), true,
535                            GlobalValue::PrivateLinkage, StrConst,
536                            kAsanGenPrefix);
537  GV->setUnnamedAddr(true);  // Ok to merge these.
538  GV->setAlignment(1);  // Strings may not be merged w/o setting align 1.
539  return GV;
540}
541
542static bool GlobalWasGeneratedByAsan(GlobalVariable *G) {
543  return G->getName().find(kAsanGenPrefix) == 0;
544}
545
546Value *AddressSanitizer::memToShadow(Value *Shadow, IRBuilder<> &IRB) {
547  // Shadow >> scale
548  Shadow = IRB.CreateLShr(Shadow, Mapping.Scale);
549  if (Mapping.Offset == 0)
550    return Shadow;
551  // (Shadow >> scale) | offset
552  if (Mapping.OrShadowOffset)
553    return IRB.CreateOr(Shadow, ConstantInt::get(IntptrTy, Mapping.Offset));
554  else
555    return IRB.CreateAdd(Shadow, ConstantInt::get(IntptrTy, Mapping.Offset));
556}
557
558void AddressSanitizer::instrumentMemIntrinsicParam(
559    Instruction *OrigIns,
560    Value *Addr, Value *Size, Instruction *InsertBefore, bool IsWrite) {
561  IRBuilder<> IRB(InsertBefore);
562  if (Size->getType() != IntptrTy)
563    Size = IRB.CreateIntCast(Size, IntptrTy, false);
564  // Check the first byte.
565  instrumentAddress(OrigIns, InsertBefore, Addr, 8, IsWrite, Size);
566  // Check the last byte.
567  IRB.SetInsertPoint(InsertBefore);
568  Value *SizeMinusOne = IRB.CreateSub(Size, ConstantInt::get(IntptrTy, 1));
569  Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
570  Value *AddrLast = IRB.CreateAdd(AddrLong, SizeMinusOne);
571  instrumentAddress(OrigIns, InsertBefore, AddrLast, 8, IsWrite, Size);
572}
573
574// Instrument memset/memmove/memcpy
575bool AddressSanitizer::instrumentMemIntrinsic(MemIntrinsic *MI) {
576  Value *Dst = MI->getDest();
577  MemTransferInst *MemTran = dyn_cast<MemTransferInst>(MI);
578  Value *Src = MemTran ? MemTran->getSource() : 0;
579  Value *Length = MI->getLength();
580
581  Constant *ConstLength = dyn_cast<Constant>(Length);
582  Instruction *InsertBefore = MI;
583  if (ConstLength) {
584    if (ConstLength->isNullValue()) return false;
585  } else {
586    // The size is not a constant so it could be zero -- check at run-time.
587    IRBuilder<> IRB(InsertBefore);
588
589    Value *Cmp = IRB.CreateICmpNE(Length,
590                                  Constant::getNullValue(Length->getType()));
591    InsertBefore = SplitBlockAndInsertIfThen(cast<Instruction>(Cmp), false);
592  }
593
594  instrumentMemIntrinsicParam(MI, Dst, Length, InsertBefore, true);
595  if (Src)
596    instrumentMemIntrinsicParam(MI, Src, Length, InsertBefore, false);
597  return true;
598}
599
600// If I is an interesting memory access, return the PointerOperand
601// and set IsWrite. Otherwise return NULL.
602static Value *isInterestingMemoryAccess(Instruction *I, bool *IsWrite) {
603  if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
604    if (!ClInstrumentReads) return NULL;
605    *IsWrite = false;
606    return LI->getPointerOperand();
607  }
608  if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
609    if (!ClInstrumentWrites) return NULL;
610    *IsWrite = true;
611    return SI->getPointerOperand();
612  }
613  if (AtomicRMWInst *RMW = dyn_cast<AtomicRMWInst>(I)) {
614    if (!ClInstrumentAtomics) return NULL;
615    *IsWrite = true;
616    return RMW->getPointerOperand();
617  }
618  if (AtomicCmpXchgInst *XCHG = dyn_cast<AtomicCmpXchgInst>(I)) {
619    if (!ClInstrumentAtomics) return NULL;
620    *IsWrite = true;
621    return XCHG->getPointerOperand();
622  }
623  return NULL;
624}
625
626void AddressSanitizer::instrumentMop(Instruction *I) {
627  bool IsWrite = false;
628  Value *Addr = isInterestingMemoryAccess(I, &IsWrite);
629  assert(Addr);
630  if (ClOpt && ClOptGlobals) {
631    if (GlobalVariable *G = dyn_cast<GlobalVariable>(Addr)) {
632      // If initialization order checking is disabled, a simple access to a
633      // dynamically initialized global is always valid.
634      if (!CheckInitOrder)
635        return;
636      // If a global variable does not have dynamic initialization we don't
637      // have to instrument it.  However, if a global does not have initailizer
638      // at all, we assume it has dynamic initializer (in other TU).
639      if (G->hasInitializer() && !DynamicallyInitializedGlobals.Contains(G))
640        return;
641    }
642  }
643
644  Type *OrigPtrTy = Addr->getType();
645  Type *OrigTy = cast<PointerType>(OrigPtrTy)->getElementType();
646
647  assert(OrigTy->isSized());
648  uint32_t TypeSize = TD->getTypeStoreSizeInBits(OrigTy);
649
650  assert((TypeSize % 8) == 0);
651
652  // Instrument a 1-, 2-, 4-, 8-, or 16- byte access with one check.
653  if (TypeSize == 8  || TypeSize == 16 ||
654      TypeSize == 32 || TypeSize == 64 || TypeSize == 128)
655    return instrumentAddress(I, I, Addr, TypeSize, IsWrite, 0);
656  // Instrument unusual size (but still multiple of 8).
657  // We can not do it with a single check, so we do 1-byte check for the first
658  // and the last bytes. We call __asan_report_*_n(addr, real_size) to be able
659  // to report the actual access size.
660  IRBuilder<> IRB(I);
661  Value *LastByte =  IRB.CreateIntToPtr(
662      IRB.CreateAdd(IRB.CreatePointerCast(Addr, IntptrTy),
663                    ConstantInt::get(IntptrTy, TypeSize / 8 - 1)),
664      OrigPtrTy);
665  Value *Size = ConstantInt::get(IntptrTy, TypeSize / 8);
666  instrumentAddress(I, I, Addr, 8, IsWrite, Size);
667  instrumentAddress(I, I, LastByte, 8, IsWrite, Size);
668}
669
670// Validate the result of Module::getOrInsertFunction called for an interface
671// function of AddressSanitizer. If the instrumented module defines a function
672// with the same name, their prototypes must match, otherwise
673// getOrInsertFunction returns a bitcast.
674static Function *checkInterfaceFunction(Constant *FuncOrBitcast) {
675  if (isa<Function>(FuncOrBitcast)) return cast<Function>(FuncOrBitcast);
676  FuncOrBitcast->dump();
677  report_fatal_error("trying to redefine an AddressSanitizer "
678                     "interface function");
679}
680
681Instruction *AddressSanitizer::generateCrashCode(
682    Instruction *InsertBefore, Value *Addr,
683    bool IsWrite, size_t AccessSizeIndex, Value *SizeArgument) {
684  IRBuilder<> IRB(InsertBefore);
685  CallInst *Call = SizeArgument
686    ? IRB.CreateCall2(AsanErrorCallbackSized[IsWrite], Addr, SizeArgument)
687    : IRB.CreateCall(AsanErrorCallback[IsWrite][AccessSizeIndex], Addr);
688
689  // We don't do Call->setDoesNotReturn() because the BB already has
690  // UnreachableInst at the end.
691  // This EmptyAsm is required to avoid callback merge.
692  IRB.CreateCall(EmptyAsm);
693  return Call;
694}
695
696Value *AddressSanitizer::createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
697                                            Value *ShadowValue,
698                                            uint32_t TypeSize) {
699  size_t Granularity = 1 << Mapping.Scale;
700  // Addr & (Granularity - 1)
701  Value *LastAccessedByte = IRB.CreateAnd(
702      AddrLong, ConstantInt::get(IntptrTy, Granularity - 1));
703  // (Addr & (Granularity - 1)) + size - 1
704  if (TypeSize / 8 > 1)
705    LastAccessedByte = IRB.CreateAdd(
706        LastAccessedByte, ConstantInt::get(IntptrTy, TypeSize / 8 - 1));
707  // (uint8_t) ((Addr & (Granularity-1)) + size - 1)
708  LastAccessedByte = IRB.CreateIntCast(
709      LastAccessedByte, ShadowValue->getType(), false);
710  // ((uint8_t) ((Addr & (Granularity-1)) + size - 1)) >= ShadowValue
711  return IRB.CreateICmpSGE(LastAccessedByte, ShadowValue);
712}
713
714void AddressSanitizer::instrumentAddress(Instruction *OrigIns,
715                                         Instruction *InsertBefore,
716                                         Value *Addr, uint32_t TypeSize,
717                                         bool IsWrite, Value *SizeArgument) {
718  IRBuilder<> IRB(InsertBefore);
719  Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
720
721  Type *ShadowTy  = IntegerType::get(
722      *C, std::max(8U, TypeSize >> Mapping.Scale));
723  Type *ShadowPtrTy = PointerType::get(ShadowTy, 0);
724  Value *ShadowPtr = memToShadow(AddrLong, IRB);
725  Value *CmpVal = Constant::getNullValue(ShadowTy);
726  Value *ShadowValue = IRB.CreateLoad(
727      IRB.CreateIntToPtr(ShadowPtr, ShadowPtrTy));
728
729  Value *Cmp = IRB.CreateICmpNE(ShadowValue, CmpVal);
730  size_t AccessSizeIndex = TypeSizeToSizeIndex(TypeSize);
731  size_t Granularity = 1 << Mapping.Scale;
732  TerminatorInst *CrashTerm = 0;
733
734  if (ClAlwaysSlowPath || (TypeSize < 8 * Granularity)) {
735    TerminatorInst *CheckTerm =
736        SplitBlockAndInsertIfThen(cast<Instruction>(Cmp), false);
737    assert(dyn_cast<BranchInst>(CheckTerm)->isUnconditional());
738    BasicBlock *NextBB = CheckTerm->getSuccessor(0);
739    IRB.SetInsertPoint(CheckTerm);
740    Value *Cmp2 = createSlowPathCmp(IRB, AddrLong, ShadowValue, TypeSize);
741    BasicBlock *CrashBlock =
742        BasicBlock::Create(*C, "", NextBB->getParent(), NextBB);
743    CrashTerm = new UnreachableInst(*C, CrashBlock);
744    BranchInst *NewTerm = BranchInst::Create(CrashBlock, NextBB, Cmp2);
745    ReplaceInstWithInst(CheckTerm, NewTerm);
746  } else {
747    CrashTerm = SplitBlockAndInsertIfThen(cast<Instruction>(Cmp), true);
748  }
749
750  Instruction *Crash = generateCrashCode(
751      CrashTerm, AddrLong, IsWrite, AccessSizeIndex, SizeArgument);
752  Crash->setDebugLoc(OrigIns->getDebugLoc());
753}
754
755void AddressSanitizerModule::createInitializerPoisonCalls(
756    Module &M, Value *FirstAddr, Value *LastAddr) {
757  // We do all of our poisoning and unpoisoning within _GLOBAL__I_a.
758  Function *GlobalInit = M.getFunction("_GLOBAL__I_a");
759  // If that function is not present, this TU contains no globals, or they have
760  // all been optimized away
761  if (!GlobalInit)
762    return;
763
764  // Set up the arguments to our poison/unpoison functions.
765  IRBuilder<> IRB(GlobalInit->begin()->getFirstInsertionPt());
766
767  // Add a call to poison all external globals before the given function starts.
768  IRB.CreateCall2(AsanPoisonGlobals, FirstAddr, LastAddr);
769
770  // Add calls to unpoison all globals before each return instruction.
771  for (Function::iterator I = GlobalInit->begin(), E = GlobalInit->end();
772      I != E; ++I) {
773    if (ReturnInst *RI = dyn_cast<ReturnInst>(I->getTerminator())) {
774      CallInst::Create(AsanUnpoisonGlobals, "", RI);
775    }
776  }
777}
778
779bool AddressSanitizerModule::ShouldInstrumentGlobal(GlobalVariable *G) {
780  Type *Ty = cast<PointerType>(G->getType())->getElementType();
781  DEBUG(dbgs() << "GLOBAL: " << *G << "\n");
782
783  if (BL->isIn(*G)) return false;
784  if (!Ty->isSized()) return false;
785  if (!G->hasInitializer()) return false;
786  if (GlobalWasGeneratedByAsan(G)) return false;  // Our own global.
787  // Touch only those globals that will not be defined in other modules.
788  // Don't handle ODR type linkages since other modules may be built w/o asan.
789  if (G->getLinkage() != GlobalVariable::ExternalLinkage &&
790      G->getLinkage() != GlobalVariable::PrivateLinkage &&
791      G->getLinkage() != GlobalVariable::InternalLinkage)
792    return false;
793  // Two problems with thread-locals:
794  //   - The address of the main thread's copy can't be computed at link-time.
795  //   - Need to poison all copies, not just the main thread's one.
796  if (G->isThreadLocal())
797    return false;
798  // For now, just ignore this Alloca if the alignment is large.
799  if (G->getAlignment() > RedzoneSize()) return false;
800
801  // Ignore all the globals with the names starting with "\01L_OBJC_".
802  // Many of those are put into the .cstring section. The linker compresses
803  // that section by removing the spare \0s after the string terminator, so
804  // our redzones get broken.
805  if ((G->getName().find("\01L_OBJC_") == 0) ||
806      (G->getName().find("\01l_OBJC_") == 0)) {
807    DEBUG(dbgs() << "Ignoring \\01L_OBJC_* global: " << *G);
808    return false;
809  }
810
811  if (G->hasSection()) {
812    StringRef Section(G->getSection());
813    // Ignore the globals from the __OBJC section. The ObjC runtime assumes
814    // those conform to /usr/lib/objc/runtime.h, so we can't add redzones to
815    // them.
816    if ((Section.find("__OBJC,") == 0) ||
817        (Section.find("__DATA, __objc_") == 0)) {
818      DEBUG(dbgs() << "Ignoring ObjC runtime global: " << *G);
819      return false;
820    }
821    // See http://code.google.com/p/address-sanitizer/issues/detail?id=32
822    // Constant CFString instances are compiled in the following way:
823    //  -- the string buffer is emitted into
824    //     __TEXT,__cstring,cstring_literals
825    //  -- the constant NSConstantString structure referencing that buffer
826    //     is placed into __DATA,__cfstring
827    // Therefore there's no point in placing redzones into __DATA,__cfstring.
828    // Moreover, it causes the linker to crash on OS X 10.7
829    if (Section.find("__DATA,__cfstring") == 0) {
830      DEBUG(dbgs() << "Ignoring CFString: " << *G);
831      return false;
832    }
833  }
834
835  return true;
836}
837
838void AddressSanitizerModule::initializeCallbacks(Module &M) {
839  IRBuilder<> IRB(*C);
840  // Declare our poisoning and unpoisoning functions.
841  AsanPoisonGlobals = checkInterfaceFunction(M.getOrInsertFunction(
842      kAsanPoisonGlobalsName, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
843  AsanPoisonGlobals->setLinkage(Function::ExternalLinkage);
844  AsanUnpoisonGlobals = checkInterfaceFunction(M.getOrInsertFunction(
845      kAsanUnpoisonGlobalsName, IRB.getVoidTy(), NULL));
846  AsanUnpoisonGlobals->setLinkage(Function::ExternalLinkage);
847  // Declare functions that register/unregister globals.
848  AsanRegisterGlobals = checkInterfaceFunction(M.getOrInsertFunction(
849      kAsanRegisterGlobalsName, IRB.getVoidTy(),
850      IntptrTy, IntptrTy, NULL));
851  AsanRegisterGlobals->setLinkage(Function::ExternalLinkage);
852  AsanUnregisterGlobals = checkInterfaceFunction(M.getOrInsertFunction(
853      kAsanUnregisterGlobalsName,
854      IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
855  AsanUnregisterGlobals->setLinkage(Function::ExternalLinkage);
856}
857
858// This function replaces all global variables with new variables that have
859// trailing redzones. It also creates a function that poisons
860// redzones and inserts this function into llvm.global_ctors.
861bool AddressSanitizerModule::runOnModule(Module &M) {
862  if (!ClGlobals) return false;
863  TD = getAnalysisIfAvailable<DataLayout>();
864  if (!TD)
865    return false;
866  BL.reset(new BlackList(BlacklistFile));
867  if (BL->isIn(M)) return false;
868  C = &(M.getContext());
869  int LongSize = TD->getPointerSizeInBits();
870  IntptrTy = Type::getIntNTy(*C, LongSize);
871  Mapping = getShadowMapping(M, LongSize, ZeroBaseShadow);
872  initializeCallbacks(M);
873  DynamicallyInitializedGlobals.Init(M);
874
875  SmallVector<GlobalVariable *, 16> GlobalsToChange;
876
877  for (Module::GlobalListType::iterator G = M.global_begin(),
878       E = M.global_end(); G != E; ++G) {
879    if (ShouldInstrumentGlobal(G))
880      GlobalsToChange.push_back(G);
881  }
882
883  size_t n = GlobalsToChange.size();
884  if (n == 0) return false;
885
886  // A global is described by a structure
887  //   size_t beg;
888  //   size_t size;
889  //   size_t size_with_redzone;
890  //   const char *name;
891  //   const char *module_name;
892  //   size_t has_dynamic_init;
893  // We initialize an array of such structures and pass it to a run-time call.
894  StructType *GlobalStructTy = StructType::get(IntptrTy, IntptrTy,
895                                               IntptrTy, IntptrTy,
896                                               IntptrTy, IntptrTy, NULL);
897  SmallVector<Constant *, 16> Initializers(n), DynamicInit;
898
899
900  Function *CtorFunc = M.getFunction(kAsanModuleCtorName);
901  assert(CtorFunc);
902  IRBuilder<> IRB(CtorFunc->getEntryBlock().getTerminator());
903
904  // The addresses of the first and last dynamically initialized globals in
905  // this TU.  Used in initialization order checking.
906  Value *FirstDynamic = 0, *LastDynamic = 0;
907
908  GlobalVariable *ModuleName = createPrivateGlobalForString(
909      M, M.getModuleIdentifier());
910
911  for (size_t i = 0; i < n; i++) {
912    static const uint64_t kMaxGlobalRedzone = 1 << 18;
913    GlobalVariable *G = GlobalsToChange[i];
914    PointerType *PtrTy = cast<PointerType>(G->getType());
915    Type *Ty = PtrTy->getElementType();
916    uint64_t SizeInBytes = TD->getTypeAllocSize(Ty);
917    uint64_t MinRZ = RedzoneSize();
918    // MinRZ <= RZ <= kMaxGlobalRedzone
919    // and trying to make RZ to be ~ 1/4 of SizeInBytes.
920    uint64_t RZ = std::max(MinRZ,
921                         std::min(kMaxGlobalRedzone,
922                                  (SizeInBytes / MinRZ / 4) * MinRZ));
923    uint64_t RightRedzoneSize = RZ;
924    // Round up to MinRZ
925    if (SizeInBytes % MinRZ)
926      RightRedzoneSize += MinRZ - (SizeInBytes % MinRZ);
927    assert(((RightRedzoneSize + SizeInBytes) % MinRZ) == 0);
928    Type *RightRedZoneTy = ArrayType::get(IRB.getInt8Ty(), RightRedzoneSize);
929    // Determine whether this global should be poisoned in initialization.
930    bool GlobalHasDynamicInitializer =
931        DynamicallyInitializedGlobals.Contains(G);
932    // Don't check initialization order if this global is blacklisted.
933    GlobalHasDynamicInitializer &= !BL->isInInit(*G);
934
935    StructType *NewTy = StructType::get(Ty, RightRedZoneTy, NULL);
936    Constant *NewInitializer = ConstantStruct::get(
937        NewTy, G->getInitializer(),
938        Constant::getNullValue(RightRedZoneTy), NULL);
939
940    GlobalVariable *Name = createPrivateGlobalForString(M, G->getName());
941
942    // Create a new global variable with enough space for a redzone.
943    GlobalVariable *NewGlobal = new GlobalVariable(
944        M, NewTy, G->isConstant(), G->getLinkage(),
945        NewInitializer, "", G, G->getThreadLocalMode());
946    NewGlobal->copyAttributesFrom(G);
947    NewGlobal->setAlignment(MinRZ);
948
949    Value *Indices2[2];
950    Indices2[0] = IRB.getInt32(0);
951    Indices2[1] = IRB.getInt32(0);
952
953    G->replaceAllUsesWith(
954        ConstantExpr::getGetElementPtr(NewGlobal, Indices2, true));
955    NewGlobal->takeName(G);
956    G->eraseFromParent();
957
958    Initializers[i] = ConstantStruct::get(
959        GlobalStructTy,
960        ConstantExpr::getPointerCast(NewGlobal, IntptrTy),
961        ConstantInt::get(IntptrTy, SizeInBytes),
962        ConstantInt::get(IntptrTy, SizeInBytes + RightRedzoneSize),
963        ConstantExpr::getPointerCast(Name, IntptrTy),
964        ConstantExpr::getPointerCast(ModuleName, IntptrTy),
965        ConstantInt::get(IntptrTy, GlobalHasDynamicInitializer),
966        NULL);
967
968    // Populate the first and last globals declared in this TU.
969    if (CheckInitOrder && GlobalHasDynamicInitializer) {
970      LastDynamic = ConstantExpr::getPointerCast(NewGlobal, IntptrTy);
971      if (FirstDynamic == 0)
972        FirstDynamic = LastDynamic;
973    }
974
975    DEBUG(dbgs() << "NEW GLOBAL: " << *NewGlobal << "\n");
976  }
977
978  ArrayType *ArrayOfGlobalStructTy = ArrayType::get(GlobalStructTy, n);
979  GlobalVariable *AllGlobals = new GlobalVariable(
980      M, ArrayOfGlobalStructTy, false, GlobalVariable::PrivateLinkage,
981      ConstantArray::get(ArrayOfGlobalStructTy, Initializers), "");
982
983  // Create calls for poisoning before initializers run and unpoisoning after.
984  if (CheckInitOrder && FirstDynamic && LastDynamic)
985    createInitializerPoisonCalls(M, FirstDynamic, LastDynamic);
986  IRB.CreateCall2(AsanRegisterGlobals,
987                  IRB.CreatePointerCast(AllGlobals, IntptrTy),
988                  ConstantInt::get(IntptrTy, n));
989
990  // We also need to unregister globals at the end, e.g. when a shared library
991  // gets closed.
992  Function *AsanDtorFunction = Function::Create(
993      FunctionType::get(Type::getVoidTy(*C), false),
994      GlobalValue::InternalLinkage, kAsanModuleDtorName, &M);
995  BasicBlock *AsanDtorBB = BasicBlock::Create(*C, "", AsanDtorFunction);
996  IRBuilder<> IRB_Dtor(ReturnInst::Create(*C, AsanDtorBB));
997  IRB_Dtor.CreateCall2(AsanUnregisterGlobals,
998                       IRB.CreatePointerCast(AllGlobals, IntptrTy),
999                       ConstantInt::get(IntptrTy, n));
1000  appendToGlobalDtors(M, AsanDtorFunction, kAsanCtorAndCtorPriority);
1001
1002  DEBUG(dbgs() << M);
1003  return true;
1004}
1005
1006void AddressSanitizer::initializeCallbacks(Module &M) {
1007  IRBuilder<> IRB(*C);
1008  // Create __asan_report* callbacks.
1009  for (size_t AccessIsWrite = 0; AccessIsWrite <= 1; AccessIsWrite++) {
1010    for (size_t AccessSizeIndex = 0; AccessSizeIndex < kNumberOfAccessSizes;
1011         AccessSizeIndex++) {
1012      // IsWrite and TypeSize are encoded in the function name.
1013      std::string FunctionName = std::string(kAsanReportErrorTemplate) +
1014          (AccessIsWrite ? "store" : "load") + itostr(1 << AccessSizeIndex);
1015      // If we are merging crash callbacks, they have two parameters.
1016      AsanErrorCallback[AccessIsWrite][AccessSizeIndex] =
1017          checkInterfaceFunction(M.getOrInsertFunction(
1018              FunctionName, IRB.getVoidTy(), IntptrTy, NULL));
1019    }
1020  }
1021  AsanErrorCallbackSized[0] = checkInterfaceFunction(M.getOrInsertFunction(
1022              kAsanReportLoadN, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1023  AsanErrorCallbackSized[1] = checkInterfaceFunction(M.getOrInsertFunction(
1024              kAsanReportStoreN, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1025
1026  AsanHandleNoReturnFunc = checkInterfaceFunction(M.getOrInsertFunction(
1027      kAsanHandleNoReturnName, IRB.getVoidTy(), NULL));
1028  // We insert an empty inline asm after __asan_report* to avoid callback merge.
1029  EmptyAsm = InlineAsm::get(FunctionType::get(IRB.getVoidTy(), false),
1030                            StringRef(""), StringRef(""),
1031                            /*hasSideEffects=*/true);
1032}
1033
1034void AddressSanitizer::emitShadowMapping(Module &M, IRBuilder<> &IRB) const {
1035  // Tell the values of mapping offset and scale to the run-time.
1036  GlobalValue *asan_mapping_offset =
1037      new GlobalVariable(M, IntptrTy, true, GlobalValue::LinkOnceODRLinkage,
1038                     ConstantInt::get(IntptrTy, Mapping.Offset),
1039                     kAsanMappingOffsetName);
1040  // Read the global, otherwise it may be optimized away.
1041  IRB.CreateLoad(asan_mapping_offset, true);
1042
1043  GlobalValue *asan_mapping_scale =
1044      new GlobalVariable(M, IntptrTy, true, GlobalValue::LinkOnceODRLinkage,
1045                         ConstantInt::get(IntptrTy, Mapping.Scale),
1046                         kAsanMappingScaleName);
1047  // Read the global, otherwise it may be optimized away.
1048  IRB.CreateLoad(asan_mapping_scale, true);
1049}
1050
1051// virtual
1052bool AddressSanitizer::doInitialization(Module &M) {
1053  // Initialize the private fields. No one has accessed them before.
1054  TD = getAnalysisIfAvailable<DataLayout>();
1055
1056  if (!TD)
1057    return false;
1058  BL.reset(new BlackList(BlacklistFile));
1059  DynamicallyInitializedGlobals.Init(M);
1060
1061  C = &(M.getContext());
1062  LongSize = TD->getPointerSizeInBits();
1063  IntptrTy = Type::getIntNTy(*C, LongSize);
1064
1065  AsanCtorFunction = Function::Create(
1066      FunctionType::get(Type::getVoidTy(*C), false),
1067      GlobalValue::InternalLinkage, kAsanModuleCtorName, &M);
1068  BasicBlock *AsanCtorBB = BasicBlock::Create(*C, "", AsanCtorFunction);
1069  // call __asan_init in the module ctor.
1070  IRBuilder<> IRB(ReturnInst::Create(*C, AsanCtorBB));
1071  AsanInitFunction = checkInterfaceFunction(
1072      M.getOrInsertFunction(kAsanInitName, IRB.getVoidTy(), NULL));
1073  AsanInitFunction->setLinkage(Function::ExternalLinkage);
1074  IRB.CreateCall(AsanInitFunction);
1075
1076  Mapping = getShadowMapping(M, LongSize, ZeroBaseShadow);
1077  emitShadowMapping(M, IRB);
1078
1079  appendToGlobalCtors(M, AsanCtorFunction, kAsanCtorAndCtorPriority);
1080  return true;
1081}
1082
1083bool AddressSanitizer::maybeInsertAsanInitAtFunctionEntry(Function &F) {
1084  // For each NSObject descendant having a +load method, this method is invoked
1085  // by the ObjC runtime before any of the static constructors is called.
1086  // Therefore we need to instrument such methods with a call to __asan_init
1087  // at the beginning in order to initialize our runtime before any access to
1088  // the shadow memory.
1089  // We cannot just ignore these methods, because they may call other
1090  // instrumented functions.
1091  if (F.getName().find(" load]") != std::string::npos) {
1092    IRBuilder<> IRB(F.begin()->begin());
1093    IRB.CreateCall(AsanInitFunction);
1094    return true;
1095  }
1096  return false;
1097}
1098
1099bool AddressSanitizer::runOnFunction(Function &F) {
1100  if (BL->isIn(F)) return false;
1101  if (&F == AsanCtorFunction) return false;
1102  if (F.getLinkage() == GlobalValue::AvailableExternallyLinkage) return false;
1103  DEBUG(dbgs() << "ASAN instrumenting:\n" << F << "\n");
1104  initializeCallbacks(*F.getParent());
1105
1106  // If needed, insert __asan_init before checking for SanitizeAddress attr.
1107  maybeInsertAsanInitAtFunctionEntry(F);
1108
1109  if (!F.getAttributes().hasAttribute(AttributeSet::FunctionIndex,
1110                                      Attribute::SanitizeAddress))
1111    return false;
1112
1113  if (!ClDebugFunc.empty() && ClDebugFunc != F.getName())
1114    return false;
1115
1116  // We want to instrument every address only once per basic block (unless there
1117  // are calls between uses).
1118  SmallSet<Value*, 16> TempsToInstrument;
1119  SmallVector<Instruction*, 16> ToInstrument;
1120  SmallVector<Instruction*, 8> NoReturnCalls;
1121  bool IsWrite;
1122
1123  // Fill the set of memory operations to instrument.
1124  for (Function::iterator FI = F.begin(), FE = F.end();
1125       FI != FE; ++FI) {
1126    TempsToInstrument.clear();
1127    int NumInsnsPerBB = 0;
1128    for (BasicBlock::iterator BI = FI->begin(), BE = FI->end();
1129         BI != BE; ++BI) {
1130      if (LooksLikeCodeInBug11395(BI)) return false;
1131      if (Value *Addr = isInterestingMemoryAccess(BI, &IsWrite)) {
1132        if (ClOpt && ClOptSameTemp) {
1133          if (!TempsToInstrument.insert(Addr))
1134            continue;  // We've seen this temp in the current BB.
1135        }
1136      } else if (isa<MemIntrinsic>(BI) && ClMemIntrin) {
1137        // ok, take it.
1138      } else {
1139        CallSite CS(BI);
1140        if (CS) {
1141          // A call inside BB.
1142          TempsToInstrument.clear();
1143          if (CS.doesNotReturn())
1144            NoReturnCalls.push_back(CS.getInstruction());
1145        }
1146        continue;
1147      }
1148      ToInstrument.push_back(BI);
1149      NumInsnsPerBB++;
1150      if (NumInsnsPerBB >= ClMaxInsnsToInstrumentPerBB)
1151        break;
1152    }
1153  }
1154
1155  // Instrument.
1156  int NumInstrumented = 0;
1157  for (size_t i = 0, n = ToInstrument.size(); i != n; i++) {
1158    Instruction *Inst = ToInstrument[i];
1159    if (ClDebugMin < 0 || ClDebugMax < 0 ||
1160        (NumInstrumented >= ClDebugMin && NumInstrumented <= ClDebugMax)) {
1161      if (isInterestingMemoryAccess(Inst, &IsWrite))
1162        instrumentMop(Inst);
1163      else
1164        instrumentMemIntrinsic(cast<MemIntrinsic>(Inst));
1165    }
1166    NumInstrumented++;
1167  }
1168
1169  FunctionStackPoisoner FSP(F, *this);
1170  bool ChangedStack = FSP.runOnFunction();
1171
1172  // We must unpoison the stack before every NoReturn call (throw, _exit, etc).
1173  // See e.g. http://code.google.com/p/address-sanitizer/issues/detail?id=37
1174  for (size_t i = 0, n = NoReturnCalls.size(); i != n; i++) {
1175    Instruction *CI = NoReturnCalls[i];
1176    IRBuilder<> IRB(CI);
1177    IRB.CreateCall(AsanHandleNoReturnFunc);
1178  }
1179  DEBUG(dbgs() << "ASAN done instrumenting:\n" << F << "\n");
1180
1181  return NumInstrumented > 0 || ChangedStack || !NoReturnCalls.empty();
1182}
1183
1184static uint64_t ValueForPoison(uint64_t PoisonByte, size_t ShadowRedzoneSize) {
1185  if (ShadowRedzoneSize == 1) return PoisonByte;
1186  if (ShadowRedzoneSize == 2) return (PoisonByte << 8) + PoisonByte;
1187  if (ShadowRedzoneSize == 4)
1188    return (PoisonByte << 24) + (PoisonByte << 16) +
1189        (PoisonByte << 8) + (PoisonByte);
1190  llvm_unreachable("ShadowRedzoneSize is either 1, 2 or 4");
1191}
1192
1193static void PoisonShadowPartialRightRedzone(uint8_t *Shadow,
1194                                            size_t Size,
1195                                            size_t RZSize,
1196                                            size_t ShadowGranularity,
1197                                            uint8_t Magic) {
1198  for (size_t i = 0; i < RZSize;
1199       i+= ShadowGranularity, Shadow++) {
1200    if (i + ShadowGranularity <= Size) {
1201      *Shadow = 0;  // fully addressable
1202    } else if (i >= Size) {
1203      *Shadow = Magic;  // unaddressable
1204    } else {
1205      *Shadow = Size - i;  // first Size-i bytes are addressable
1206    }
1207  }
1208}
1209
1210// Workaround for bug 11395: we don't want to instrument stack in functions
1211// with large assembly blobs (32-bit only), otherwise reg alloc may crash.
1212// FIXME: remove once the bug 11395 is fixed.
1213bool AddressSanitizer::LooksLikeCodeInBug11395(Instruction *I) {
1214  if (LongSize != 32) return false;
1215  CallInst *CI = dyn_cast<CallInst>(I);
1216  if (!CI || !CI->isInlineAsm()) return false;
1217  if (CI->getNumArgOperands() <= 5) return false;
1218  // We have inline assembly with quite a few arguments.
1219  return true;
1220}
1221
1222void FunctionStackPoisoner::initializeCallbacks(Module &M) {
1223  IRBuilder<> IRB(*C);
1224  AsanStackMallocFunc = checkInterfaceFunction(M.getOrInsertFunction(
1225      kAsanStackMallocName, IntptrTy, IntptrTy, IntptrTy, NULL));
1226  AsanStackFreeFunc = checkInterfaceFunction(M.getOrInsertFunction(
1227      kAsanStackFreeName, IRB.getVoidTy(),
1228      IntptrTy, IntptrTy, IntptrTy, NULL));
1229  AsanPoisonStackMemoryFunc = checkInterfaceFunction(M.getOrInsertFunction(
1230      kAsanPoisonStackMemoryName, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1231  AsanUnpoisonStackMemoryFunc = checkInterfaceFunction(M.getOrInsertFunction(
1232      kAsanUnpoisonStackMemoryName, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1233}
1234
1235void FunctionStackPoisoner::poisonRedZones(
1236  const ArrayRef<AllocaInst*> &AllocaVec, IRBuilder<> IRB, Value *ShadowBase,
1237  bool DoPoison) {
1238  size_t ShadowRZSize = RedzoneSize() >> Mapping.Scale;
1239  assert(ShadowRZSize >= 1 && ShadowRZSize <= 4);
1240  Type *RZTy = Type::getIntNTy(*C, ShadowRZSize * 8);
1241  Type *RZPtrTy = PointerType::get(RZTy, 0);
1242
1243  Value *PoisonLeft  = ConstantInt::get(RZTy,
1244    ValueForPoison(DoPoison ? kAsanStackLeftRedzoneMagic : 0LL, ShadowRZSize));
1245  Value *PoisonMid   = ConstantInt::get(RZTy,
1246    ValueForPoison(DoPoison ? kAsanStackMidRedzoneMagic : 0LL, ShadowRZSize));
1247  Value *PoisonRight = ConstantInt::get(RZTy,
1248    ValueForPoison(DoPoison ? kAsanStackRightRedzoneMagic : 0LL, ShadowRZSize));
1249
1250  // poison the first red zone.
1251  IRB.CreateStore(PoisonLeft, IRB.CreateIntToPtr(ShadowBase, RZPtrTy));
1252
1253  // poison all other red zones.
1254  uint64_t Pos = RedzoneSize();
1255  for (size_t i = 0, n = AllocaVec.size(); i < n; i++) {
1256    AllocaInst *AI = AllocaVec[i];
1257    uint64_t SizeInBytes = getAllocaSizeInBytes(AI);
1258    uint64_t AlignedSize = getAlignedAllocaSize(AI);
1259    assert(AlignedSize - SizeInBytes < RedzoneSize());
1260    Value *Ptr = NULL;
1261
1262    Pos += AlignedSize;
1263
1264    assert(ShadowBase->getType() == IntptrTy);
1265    if (SizeInBytes < AlignedSize) {
1266      // Poison the partial redzone at right
1267      Ptr = IRB.CreateAdd(
1268          ShadowBase, ConstantInt::get(IntptrTy,
1269                                       (Pos >> Mapping.Scale) - ShadowRZSize));
1270      size_t AddressableBytes = RedzoneSize() - (AlignedSize - SizeInBytes);
1271      uint32_t Poison = 0;
1272      if (DoPoison) {
1273        PoisonShadowPartialRightRedzone((uint8_t*)&Poison, AddressableBytes,
1274                                        RedzoneSize(),
1275                                        1ULL << Mapping.Scale,
1276                                        kAsanStackPartialRedzoneMagic);
1277      }
1278      Value *PartialPoison = ConstantInt::get(RZTy, Poison);
1279      IRB.CreateStore(PartialPoison, IRB.CreateIntToPtr(Ptr, RZPtrTy));
1280    }
1281
1282    // Poison the full redzone at right.
1283    Ptr = IRB.CreateAdd(ShadowBase,
1284                        ConstantInt::get(IntptrTy, Pos >> Mapping.Scale));
1285    bool LastAlloca = (i == AllocaVec.size() - 1);
1286    Value *Poison = LastAlloca ? PoisonRight : PoisonMid;
1287    IRB.CreateStore(Poison, IRB.CreateIntToPtr(Ptr, RZPtrTy));
1288
1289    Pos += RedzoneSize();
1290  }
1291}
1292
1293void FunctionStackPoisoner::poisonStack() {
1294  uint64_t LocalStackSize = TotalStackSize +
1295                            (AllocaVec.size() + 1) * RedzoneSize();
1296
1297  bool DoStackMalloc = ASan.CheckUseAfterReturn
1298      && LocalStackSize <= kMaxStackMallocSize;
1299
1300  assert(AllocaVec.size() > 0);
1301  Instruction *InsBefore = AllocaVec[0];
1302  IRBuilder<> IRB(InsBefore);
1303
1304
1305  Type *ByteArrayTy = ArrayType::get(IRB.getInt8Ty(), LocalStackSize);
1306  AllocaInst *MyAlloca =
1307      new AllocaInst(ByteArrayTy, "MyAlloca", InsBefore);
1308  if (ClRealignStack && StackAlignment < RedzoneSize())
1309    StackAlignment = RedzoneSize();
1310  MyAlloca->setAlignment(StackAlignment);
1311  assert(MyAlloca->isStaticAlloca());
1312  Value *OrigStackBase = IRB.CreatePointerCast(MyAlloca, IntptrTy);
1313  Value *LocalStackBase = OrigStackBase;
1314
1315  if (DoStackMalloc) {
1316    LocalStackBase = IRB.CreateCall2(AsanStackMallocFunc,
1317        ConstantInt::get(IntptrTy, LocalStackSize), OrigStackBase);
1318  }
1319
1320  // This string will be parsed by the run-time (DescribeAddressIfStack).
1321  SmallString<2048> StackDescriptionStorage;
1322  raw_svector_ostream StackDescription(StackDescriptionStorage);
1323  StackDescription << AllocaVec.size() << " ";
1324
1325  // Insert poison calls for lifetime intrinsics for alloca.
1326  bool HavePoisonedAllocas = false;
1327  for (size_t i = 0, n = AllocaPoisonCallVec.size(); i < n; i++) {
1328    const AllocaPoisonCall &APC = AllocaPoisonCallVec[i];
1329    IntrinsicInst *II = APC.InsBefore;
1330    AllocaInst *AI = findAllocaForValue(II->getArgOperand(1));
1331    assert(AI);
1332    IRBuilder<> IRB(II);
1333    poisonAlloca(AI, APC.Size, IRB, APC.DoPoison);
1334    HavePoisonedAllocas |= APC.DoPoison;
1335  }
1336
1337  uint64_t Pos = RedzoneSize();
1338  // Replace Alloca instructions with base+offset.
1339  for (size_t i = 0, n = AllocaVec.size(); i < n; i++) {
1340    AllocaInst *AI = AllocaVec[i];
1341    uint64_t SizeInBytes = getAllocaSizeInBytes(AI);
1342    StringRef Name = AI->getName();
1343    StackDescription << Pos << " " << SizeInBytes << " "
1344                     << Name.size() << " " << Name << " ";
1345    uint64_t AlignedSize = getAlignedAllocaSize(AI);
1346    assert((AlignedSize % RedzoneSize()) == 0);
1347    Value *NewAllocaPtr = IRB.CreateIntToPtr(
1348            IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy, Pos)),
1349            AI->getType());
1350    replaceDbgDeclareForAlloca(AI, NewAllocaPtr, DIB);
1351    AI->replaceAllUsesWith(NewAllocaPtr);
1352    Pos += AlignedSize + RedzoneSize();
1353  }
1354  assert(Pos == LocalStackSize);
1355
1356  // The left-most redzone has enough space for at least 4 pointers.
1357  // Write the Magic value to redzone[0].
1358  Value *BasePlus0 = IRB.CreateIntToPtr(LocalStackBase, IntptrPtrTy);
1359  IRB.CreateStore(ConstantInt::get(IntptrTy, kCurrentStackFrameMagic),
1360                  BasePlus0);
1361  // Write the frame description constant to redzone[1].
1362  Value *BasePlus1 = IRB.CreateIntToPtr(
1363    IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy, ASan.LongSize/8)),
1364    IntptrPtrTy);
1365  GlobalVariable *StackDescriptionGlobal =
1366      createPrivateGlobalForString(*F.getParent(), StackDescription.str());
1367  Value *Description = IRB.CreatePointerCast(StackDescriptionGlobal,
1368                                             IntptrTy);
1369  IRB.CreateStore(Description, BasePlus1);
1370  // Write the PC to redzone[2].
1371  Value *BasePlus2 = IRB.CreateIntToPtr(
1372    IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy,
1373                                                   2 * ASan.LongSize/8)),
1374    IntptrPtrTy);
1375  IRB.CreateStore(IRB.CreatePointerCast(&F, IntptrTy), BasePlus2);
1376
1377  // Poison the stack redzones at the entry.
1378  Value *ShadowBase = ASan.memToShadow(LocalStackBase, IRB);
1379  poisonRedZones(AllocaVec, IRB, ShadowBase, true);
1380
1381  // Unpoison the stack before all ret instructions.
1382  for (size_t i = 0, n = RetVec.size(); i < n; i++) {
1383    Instruction *Ret = RetVec[i];
1384    IRBuilder<> IRBRet(Ret);
1385    // Mark the current frame as retired.
1386    IRBRet.CreateStore(ConstantInt::get(IntptrTy, kRetiredStackFrameMagic),
1387                       BasePlus0);
1388    // Unpoison the stack.
1389    poisonRedZones(AllocaVec, IRBRet, ShadowBase, false);
1390    if (DoStackMalloc) {
1391      // In use-after-return mode, mark the whole stack frame unaddressable.
1392      IRBRet.CreateCall3(AsanStackFreeFunc, LocalStackBase,
1393                         ConstantInt::get(IntptrTy, LocalStackSize),
1394                         OrigStackBase);
1395    } else if (HavePoisonedAllocas) {
1396      // If we poisoned some allocas in llvm.lifetime analysis,
1397      // unpoison whole stack frame now.
1398      assert(LocalStackBase == OrigStackBase);
1399      poisonAlloca(LocalStackBase, LocalStackSize, IRBRet, false);
1400    }
1401  }
1402
1403  // We are done. Remove the old unused alloca instructions.
1404  for (size_t i = 0, n = AllocaVec.size(); i < n; i++)
1405    AllocaVec[i]->eraseFromParent();
1406}
1407
1408void FunctionStackPoisoner::poisonAlloca(Value *V, uint64_t Size,
1409                                         IRBuilder<> IRB, bool DoPoison) {
1410  // For now just insert the call to ASan runtime.
1411  Value *AddrArg = IRB.CreatePointerCast(V, IntptrTy);
1412  Value *SizeArg = ConstantInt::get(IntptrTy, Size);
1413  IRB.CreateCall2(DoPoison ? AsanPoisonStackMemoryFunc
1414                           : AsanUnpoisonStackMemoryFunc,
1415                  AddrArg, SizeArg);
1416}
1417
1418// Handling llvm.lifetime intrinsics for a given %alloca:
1419// (1) collect all llvm.lifetime.xxx(%size, %value) describing the alloca.
1420// (2) if %size is constant, poison memory for llvm.lifetime.end (to detect
1421//     invalid accesses) and unpoison it for llvm.lifetime.start (the memory
1422//     could be poisoned by previous llvm.lifetime.end instruction, as the
1423//     variable may go in and out of scope several times, e.g. in loops).
1424// (3) if we poisoned at least one %alloca in a function,
1425//     unpoison the whole stack frame at function exit.
1426
1427AllocaInst *FunctionStackPoisoner::findAllocaForValue(Value *V) {
1428  if (AllocaInst *AI = dyn_cast<AllocaInst>(V))
1429    // We're intested only in allocas we can handle.
1430    return isInterestingAlloca(*AI) ? AI : 0;
1431  // See if we've already calculated (or started to calculate) alloca for a
1432  // given value.
1433  AllocaForValueMapTy::iterator I = AllocaForValue.find(V);
1434  if (I != AllocaForValue.end())
1435    return I->second;
1436  // Store 0 while we're calculating alloca for value V to avoid
1437  // infinite recursion if the value references itself.
1438  AllocaForValue[V] = 0;
1439  AllocaInst *Res = 0;
1440  if (CastInst *CI = dyn_cast<CastInst>(V))
1441    Res = findAllocaForValue(CI->getOperand(0));
1442  else if (PHINode *PN = dyn_cast<PHINode>(V)) {
1443    for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
1444      Value *IncValue = PN->getIncomingValue(i);
1445      // Allow self-referencing phi-nodes.
1446      if (IncValue == PN) continue;
1447      AllocaInst *IncValueAI = findAllocaForValue(IncValue);
1448      // AI for incoming values should exist and should all be equal.
1449      if (IncValueAI == 0 || (Res != 0 && IncValueAI != Res))
1450        return 0;
1451      Res = IncValueAI;
1452    }
1453  }
1454  if (Res != 0)
1455    AllocaForValue[V] = Res;
1456  return Res;
1457}
1458