AddressSanitizer.cpp revision 7dadac65d375ff21b7a36bfb7642578d2f467525 
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 "BlackList.h"
19#include "llvm/Function.h"
20#include "llvm/IRBuilder.h"
21#include "llvm/InlineAsm.h"
22#include "llvm/IntrinsicInst.h"
23#include "llvm/LLVMContext.h"
24#include "llvm/Module.h"
25#include "llvm/Type.h"
26#include "llvm/ADT/ArrayRef.h"
27#include "llvm/ADT/OwningPtr.h"
28#include "llvm/ADT/SmallSet.h"
29#include "llvm/ADT/SmallString.h"
30#include "llvm/ADT/SmallVector.h"
31#include "llvm/ADT/StringExtras.h"
32#include "llvm/ADT/Triple.h"
33#include "llvm/Support/CommandLine.h"
34#include "llvm/Support/DataTypes.h"
35#include "llvm/Support/Debug.h"
36#include "llvm/Support/raw_ostream.h"
37#include "llvm/Support/system_error.h"
38#include "llvm/Target/TargetData.h"
39#include "llvm/Target/TargetMachine.h"
40#include "llvm/Transforms/Instrumentation.h"
41#include "llvm/Transforms/Utils/BasicBlockUtils.h"
42#include "llvm/Transforms/Utils/ModuleUtils.h"
43
44#include <string>
45#include <algorithm>
46
47using namespace llvm;
48
49static const uint64_t kDefaultShadowScale = 3;
50static const uint64_t kDefaultShadowOffset32 = 1ULL << 29;
51static const uint64_t kDefaultShadowOffset64 = 1ULL << 44;
52static const uint64_t kDefaultShadowOffsetAndroid = 0;
53
54static const size_t kMaxStackMallocSize = 1 << 16;  // 64K
55static const uintptr_t kCurrentStackFrameMagic = 0x41B58AB3;
56static const uintptr_t kRetiredStackFrameMagic = 0x45E0360E;
57
58static const char *kAsanModuleCtorName = "asan.module_ctor";
59static const char *kAsanModuleDtorName = "asan.module_dtor";
60static const int   kAsanCtorAndCtorPriority = 1;
61static const char *kAsanReportErrorTemplate = "__asan_report_";
62static const char *kAsanRegisterGlobalsName = "__asan_register_globals";
63static const char *kAsanUnregisterGlobalsName = "__asan_unregister_globals";
64static const char *kAsanPoisonGlobalsName = "__asan_before_dynamic_init";
65static const char *kAsanUnpoisonGlobalsName = "__asan_after_dynamic_init";
66static const char *kAsanInitName = "__asan_init";
67static const char *kAsanHandleNoReturnName = "__asan_handle_no_return";
68static const char *kAsanMappingOffsetName = "__asan_mapping_offset";
69static const char *kAsanMappingScaleName = "__asan_mapping_scale";
70static const char *kAsanStackMallocName = "__asan_stack_malloc";
71static const char *kAsanStackFreeName = "__asan_stack_free";
72
73static const int kAsanStackLeftRedzoneMagic = 0xf1;
74static const int kAsanStackMidRedzoneMagic = 0xf2;
75static const int kAsanStackRightRedzoneMagic = 0xf3;
76static const int kAsanStackPartialRedzoneMagic = 0xf4;
77
78// Accesses sizes are powers of two: 1, 2, 4, 8, 16.
79static const size_t kNumberOfAccessSizes = 5;
80
81// Command-line flags.
82
83// This flag may need to be replaced with -f[no-]asan-reads.
84static cl::opt<bool> ClInstrumentReads("asan-instrument-reads",
85       cl::desc("instrument read instructions"), cl::Hidden, cl::init(true));
86static cl::opt<bool> ClInstrumentWrites("asan-instrument-writes",
87       cl::desc("instrument write instructions"), cl::Hidden, cl::init(true));
88static cl::opt<bool> ClInstrumentAtomics("asan-instrument-atomics",
89       cl::desc("instrument atomic instructions (rmw, cmpxchg)"),
90       cl::Hidden, cl::init(true));
91static cl::opt<bool> ClAlwaysSlowPath("asan-always-slow-path",
92       cl::desc("use instrumentation with slow path for all accesses"),
93       cl::Hidden, cl::init(false));
94// This flag limits the number of instructions to be instrumented
95// in any given BB. Normally, this should be set to unlimited (INT_MAX),
96// but due to http://llvm.org/bugs/show_bug.cgi?id=12652 we temporary
97// set it to 10000.
98static cl::opt<int> ClMaxInsnsToInstrumentPerBB("asan-max-ins-per-bb",
99       cl::init(10000),
100       cl::desc("maximal number of instructions to instrument in any given BB"),
101       cl::Hidden);
102// This flag may need to be replaced with -f[no]asan-stack.
103static cl::opt<bool> ClStack("asan-stack",
104       cl::desc("Handle stack memory"), cl::Hidden, cl::init(true));
105// This flag may need to be replaced with -f[no]asan-use-after-return.
106static cl::opt<bool> ClUseAfterReturn("asan-use-after-return",
107       cl::desc("Check return-after-free"), cl::Hidden, cl::init(false));
108// This flag may need to be replaced with -f[no]asan-globals.
109static cl::opt<bool> ClGlobals("asan-globals",
110       cl::desc("Handle global objects"), cl::Hidden, cl::init(true));
111static cl::opt<bool> ClInitializers("asan-initialization-order",
112       cl::desc("Handle C++ initializer order"), cl::Hidden, cl::init(false));
113static cl::opt<bool> ClMemIntrin("asan-memintrin",
114       cl::desc("Handle memset/memcpy/memmove"), cl::Hidden, cl::init(true));
115// This flag may need to be replaced with -fasan-blacklist.
116static cl::opt<std::string>  ClBlackListFile("asan-blacklist",
117       cl::desc("File containing the list of functions to ignore "
118                "during instrumentation"), cl::Hidden);
119
120// These flags allow to change the shadow mapping.
121// The shadow mapping looks like
122//    Shadow = (Mem >> scale) + (1 << offset_log)
123static cl::opt<int> ClMappingScale("asan-mapping-scale",
124       cl::desc("scale of asan shadow mapping"), cl::Hidden, cl::init(0));
125static cl::opt<int> ClMappingOffsetLog("asan-mapping-offset-log",
126       cl::desc("offset of asan shadow mapping"), cl::Hidden, cl::init(-1));
127
128// Optimization flags. Not user visible, used mostly for testing
129// and benchmarking the tool.
130static cl::opt<bool> ClOpt("asan-opt",
131       cl::desc("Optimize instrumentation"), cl::Hidden, cl::init(true));
132static cl::opt<bool> ClOptSameTemp("asan-opt-same-temp",
133       cl::desc("Instrument the same temp just once"), cl::Hidden,
134       cl::init(true));
135static cl::opt<bool> ClOptGlobals("asan-opt-globals",
136       cl::desc("Don't instrument scalar globals"), cl::Hidden, cl::init(true));
137
138// Debug flags.
139static cl::opt<int> ClDebug("asan-debug", cl::desc("debug"), cl::Hidden,
140                            cl::init(0));
141static cl::opt<int> ClDebugStack("asan-debug-stack", cl::desc("debug stack"),
142                                 cl::Hidden, cl::init(0));
143static cl::opt<std::string> ClDebugFunc("asan-debug-func",
144                                        cl::Hidden, cl::desc("Debug func"));
145static cl::opt<int> ClDebugMin("asan-debug-min", cl::desc("Debug min inst"),
146                               cl::Hidden, cl::init(-1));
147static cl::opt<int> ClDebugMax("asan-debug-max", cl::desc("Debug man inst"),
148                               cl::Hidden, cl::init(-1));
149
150namespace {
151
152/// An object of this type is created while instrumenting every function.
153struct AsanFunctionContext {
154  AsanFunctionContext(Function &Function) : F(Function) { }
155
156  Function &F;
157};
158
159/// AddressSanitizer: instrument the code in module to find memory bugs.
160struct AddressSanitizer : public ModulePass {
161  AddressSanitizer();
162  virtual const char *getPassName() const;
163  void instrumentMop(AsanFunctionContext &AFC, Instruction *I);
164  void instrumentAddress(AsanFunctionContext &AFC,
165                         Instruction *OrigIns, IRBuilder<> &IRB,
166                         Value *Addr, uint32_t TypeSize, bool IsWrite);
167  Value *createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
168                           Value *ShadowValue, uint32_t TypeSize);
169  Instruction *generateCrashCode(Instruction *InsertBefore, Value *Addr,
170                                 bool IsWrite, size_t AccessSizeIndex);
171  bool instrumentMemIntrinsic(AsanFunctionContext &AFC, MemIntrinsic *MI);
172  void instrumentMemIntrinsicParam(AsanFunctionContext &AFC,
173                                   Instruction *OrigIns, Value *Addr,
174                                   Value *Size,
175                                   Instruction *InsertBefore, bool IsWrite);
176  Value *memToShadow(Value *Shadow, IRBuilder<> &IRB);
177  bool handleFunction(Module &M, Function &F);
178  void createInitializerPoisonCalls(Module &M,
179                                    Value *FirstAddr, Value *LastAddr);
180  bool maybeInsertAsanInitAtFunctionEntry(Function &F);
181  bool poisonStackInFunction(Module &M, Function &F);
182  virtual bool runOnModule(Module &M);
183  bool insertGlobalRedzones(Module &M);
184  static char ID;  // Pass identification, replacement for typeid
185
186 private:
187  uint64_t getAllocaSizeInBytes(AllocaInst *AI) {
188    Type *Ty = AI->getAllocatedType();
189    uint64_t SizeInBytes = TD->getTypeAllocSize(Ty);
190    return SizeInBytes;
191  }
192  uint64_t getAlignedSize(uint64_t SizeInBytes) {
193    return ((SizeInBytes + RedzoneSize - 1)
194            / RedzoneSize) * RedzoneSize;
195  }
196  uint64_t getAlignedAllocaSize(AllocaInst *AI) {
197    uint64_t SizeInBytes = getAllocaSizeInBytes(AI);
198    return getAlignedSize(SizeInBytes);
199  }
200
201  Function *checkInterfaceFunction(Constant *FuncOrBitcast);
202  bool ShouldInstrumentGlobal(GlobalVariable *G);
203  void PoisonStack(const ArrayRef<AllocaInst*> &AllocaVec, IRBuilder<> IRB,
204                   Value *ShadowBase, bool DoPoison);
205  bool LooksLikeCodeInBug11395(Instruction *I);
206  void FindDynamicInitializers(Module &M);
207  bool HasDynamicInitializer(GlobalVariable *G);
208
209  LLVMContext *C;
210  TargetData *TD;
211  uint64_t MappingOffset;
212  int MappingScale;
213  size_t RedzoneSize;
214  int LongSize;
215  Type *IntptrTy;
216  Type *IntptrPtrTy;
217  Function *AsanCtorFunction;
218  Function *AsanInitFunction;
219  Instruction *CtorInsertBefore;
220  OwningPtr<BlackList> BL;
221  // This array is indexed by AccessIsWrite and log2(AccessSize).
222  Function *AsanErrorCallback[2][kNumberOfAccessSizes];
223  InlineAsm *EmptyAsm;
224  SmallSet<GlobalValue*, 32> DynamicallyInitializedGlobals;
225};
226
227}  // namespace
228
229char AddressSanitizer::ID = 0;
230INITIALIZE_PASS(AddressSanitizer, "asan",
231    "AddressSanitizer: detects use-after-free and out-of-bounds bugs.",
232    false, false)
233AddressSanitizer::AddressSanitizer() : ModulePass(ID) { }
234ModulePass *llvm::createAddressSanitizerPass() {
235  return new AddressSanitizer();
236}
237
238const char *AddressSanitizer::getPassName() const {
239  return "AddressSanitizer";
240}
241
242static size_t TypeSizeToSizeIndex(uint32_t TypeSize) {
243  size_t Res = CountTrailingZeros_32(TypeSize / 8);
244  assert(Res < kNumberOfAccessSizes);
245  return Res;
246}
247
248// Create a constant for Str so that we can pass it to the run-time lib.
249static GlobalVariable *createPrivateGlobalForString(Module &M, StringRef Str) {
250  Constant *StrConst = ConstantDataArray::getString(M.getContext(), Str);
251  return new GlobalVariable(M, StrConst->getType(), true,
252                            GlobalValue::PrivateLinkage, StrConst, "");
253}
254
255// Split the basic block and insert an if-then code.
256// Before:
257//   Head
258//   Cmp
259//   Tail
260// After:
261//   Head
262//   if (Cmp)
263//     ThenBlock
264//   Tail
265//
266// ThenBlock block is created and its terminator is returned.
267// If Unreachable, ThenBlock is terminated with UnreachableInst, otherwise
268// it is terminated with BranchInst to Tail.
269static TerminatorInst *splitBlockAndInsertIfThen(Value *Cmp, bool Unreachable) {
270  Instruction *SplitBefore = cast<Instruction>(Cmp)->getNextNode();
271  BasicBlock *Head = SplitBefore->getParent();
272  BasicBlock *Tail = Head->splitBasicBlock(SplitBefore);
273  TerminatorInst *HeadOldTerm = Head->getTerminator();
274  LLVMContext &C = Head->getParent()->getParent()->getContext();
275  BasicBlock *ThenBlock = BasicBlock::Create(C, "", Head->getParent(), Tail);
276  TerminatorInst *CheckTerm;
277  if (Unreachable)
278    CheckTerm = new UnreachableInst(C, ThenBlock);
279  else
280    CheckTerm = BranchInst::Create(Tail, ThenBlock);
281  BranchInst *HeadNewTerm =
282    BranchInst::Create(/*ifTrue*/ThenBlock, /*ifFalse*/Tail, Cmp);
283  ReplaceInstWithInst(HeadOldTerm, HeadNewTerm);
284  return CheckTerm;
285}
286
287Value *AddressSanitizer::memToShadow(Value *Shadow, IRBuilder<> &IRB) {
288  // Shadow >> scale
289  Shadow = IRB.CreateLShr(Shadow, MappingScale);
290  if (MappingOffset == 0)
291    return Shadow;
292  // (Shadow >> scale) | offset
293  return IRB.CreateOr(Shadow, ConstantInt::get(IntptrTy,
294                                               MappingOffset));
295}
296
297void AddressSanitizer::instrumentMemIntrinsicParam(
298    AsanFunctionContext &AFC, Instruction *OrigIns,
299    Value *Addr, Value *Size, Instruction *InsertBefore, bool IsWrite) {
300  // Check the first byte.
301  {
302    IRBuilder<> IRB(InsertBefore);
303    instrumentAddress(AFC, OrigIns, IRB, Addr, 8, IsWrite);
304  }
305  // Check the last byte.
306  {
307    IRBuilder<> IRB(InsertBefore);
308    Value *SizeMinusOne = IRB.CreateSub(
309        Size, ConstantInt::get(Size->getType(), 1));
310    SizeMinusOne = IRB.CreateIntCast(SizeMinusOne, IntptrTy, false);
311    Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
312    Value *AddrPlusSizeMinisOne = IRB.CreateAdd(AddrLong, SizeMinusOne);
313    instrumentAddress(AFC, OrigIns, IRB, AddrPlusSizeMinisOne, 8, IsWrite);
314  }
315}
316
317// Instrument memset/memmove/memcpy
318bool AddressSanitizer::instrumentMemIntrinsic(AsanFunctionContext &AFC,
319                                              MemIntrinsic *MI) {
320  Value *Dst = MI->getDest();
321  MemTransferInst *MemTran = dyn_cast<MemTransferInst>(MI);
322  Value *Src = MemTran ? MemTran->getSource() : 0;
323  Value *Length = MI->getLength();
324
325  Constant *ConstLength = dyn_cast<Constant>(Length);
326  Instruction *InsertBefore = MI;
327  if (ConstLength) {
328    if (ConstLength->isNullValue()) return false;
329  } else {
330    // The size is not a constant so it could be zero -- check at run-time.
331    IRBuilder<> IRB(InsertBefore);
332
333    Value *Cmp = IRB.CreateICmpNE(Length,
334                                  Constant::getNullValue(Length->getType()));
335    InsertBefore = splitBlockAndInsertIfThen(Cmp, false);
336  }
337
338  instrumentMemIntrinsicParam(AFC, MI, Dst, Length, InsertBefore, true);
339  if (Src)
340    instrumentMemIntrinsicParam(AFC, MI, Src, Length, InsertBefore, false);
341  return true;
342}
343
344// If I is an interesting memory access, return the PointerOperand
345// and set IsWrite. Otherwise return NULL.
346static Value *isInterestingMemoryAccess(Instruction *I, bool *IsWrite) {
347  if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
348    if (!ClInstrumentReads) return NULL;
349    *IsWrite = false;
350    return LI->getPointerOperand();
351  }
352  if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
353    if (!ClInstrumentWrites) return NULL;
354    *IsWrite = true;
355    return SI->getPointerOperand();
356  }
357  if (AtomicRMWInst *RMW = dyn_cast<AtomicRMWInst>(I)) {
358    if (!ClInstrumentAtomics) return NULL;
359    *IsWrite = true;
360    return RMW->getPointerOperand();
361  }
362  if (AtomicCmpXchgInst *XCHG = dyn_cast<AtomicCmpXchgInst>(I)) {
363    if (!ClInstrumentAtomics) return NULL;
364    *IsWrite = true;
365    return XCHG->getPointerOperand();
366  }
367  return NULL;
368}
369
370void AddressSanitizer::FindDynamicInitializers(Module& M) {
371  // Clang generates metadata identifying all dynamically initialized globals.
372  NamedMDNode *DynamicGlobals =
373      M.getNamedMetadata("llvm.asan.dynamically_initialized_globals");
374  if (!DynamicGlobals)
375    return;
376  for (int i = 0, n = DynamicGlobals->getNumOperands(); i < n; ++i) {
377    MDNode *MDN = DynamicGlobals->getOperand(i);
378    assert(MDN->getNumOperands() == 1);
379    Value *VG = MDN->getOperand(0);
380    // The optimizer may optimize away a global entirely, in which case we
381    // cannot instrument access to it.
382    if (!VG)
383      continue;
384
385    GlobalVariable *G = cast<GlobalVariable>(VG);
386    DynamicallyInitializedGlobals.insert(G);
387  }
388}
389// Returns true if a global variable is initialized dynamically in this TU.
390bool AddressSanitizer::HasDynamicInitializer(GlobalVariable *G) {
391  return DynamicallyInitializedGlobals.count(G);
392}
393
394void AddressSanitizer::instrumentMop(AsanFunctionContext &AFC, Instruction *I) {
395  bool IsWrite;
396  Value *Addr = isInterestingMemoryAccess(I, &IsWrite);
397  assert(Addr);
398  if (ClOpt && ClOptGlobals) {
399    if (GlobalVariable *G = dyn_cast<GlobalVariable>(Addr)) {
400      // If initialization order checking is disabled, a simple access to a
401      // dynamically initialized global is always valid.
402      if (!ClInitializers)
403        return;
404      // If a global variable does not have dynamic initialization we don't
405      // have to instrument it.  However, if a global has external linkage, we
406      // assume it has dynamic initialization, as it may have an initializer
407      // in a different TU.
408      if (G->getLinkage() != GlobalVariable::ExternalLinkage &&
409          !HasDynamicInitializer(G))
410        return;
411    }
412  }
413
414  Type *OrigPtrTy = Addr->getType();
415  Type *OrigTy = cast<PointerType>(OrigPtrTy)->getElementType();
416
417  assert(OrigTy->isSized());
418  uint32_t TypeSize = TD->getTypeStoreSizeInBits(OrigTy);
419
420  if (TypeSize != 8  && TypeSize != 16 &&
421      TypeSize != 32 && TypeSize != 64 && TypeSize != 128) {
422    // Ignore all unusual sizes.
423    return;
424  }
425
426  IRBuilder<> IRB(I);
427  instrumentAddress(AFC, I, IRB, Addr, TypeSize, IsWrite);
428}
429
430// Validate the result of Module::getOrInsertFunction called for an interface
431// function of AddressSanitizer. If the instrumented module defines a function
432// with the same name, their prototypes must match, otherwise
433// getOrInsertFunction returns a bitcast.
434Function *AddressSanitizer::checkInterfaceFunction(Constant *FuncOrBitcast) {
435  if (isa<Function>(FuncOrBitcast)) return cast<Function>(FuncOrBitcast);
436  FuncOrBitcast->dump();
437  report_fatal_error("trying to redefine an AddressSanitizer "
438                     "interface function");
439}
440
441Instruction *AddressSanitizer::generateCrashCode(
442    Instruction *InsertBefore, Value *Addr,
443    bool IsWrite, size_t AccessSizeIndex) {
444  IRBuilder<> IRB(InsertBefore);
445  CallInst *Call = IRB.CreateCall(AsanErrorCallback[IsWrite][AccessSizeIndex],
446                                  Addr);
447  // We don't do Call->setDoesNotReturn() because the BB already has
448  // UnreachableInst at the end.
449  // This EmptyAsm is required to avoid callback merge.
450  IRB.CreateCall(EmptyAsm);
451  return Call;
452}
453
454Value *AddressSanitizer::createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
455                                            Value *ShadowValue,
456                                            uint32_t TypeSize) {
457  size_t Granularity = 1 << MappingScale;
458  // Addr & (Granularity - 1)
459  Value *LastAccessedByte = IRB.CreateAnd(
460      AddrLong, ConstantInt::get(IntptrTy, Granularity - 1));
461  // (Addr & (Granularity - 1)) + size - 1
462  if (TypeSize / 8 > 1)
463    LastAccessedByte = IRB.CreateAdd(
464        LastAccessedByte, ConstantInt::get(IntptrTy, TypeSize / 8 - 1));
465  // (uint8_t) ((Addr & (Granularity-1)) + size - 1)
466  LastAccessedByte = IRB.CreateIntCast(
467      LastAccessedByte, ShadowValue->getType(), false);
468  // ((uint8_t) ((Addr & (Granularity-1)) + size - 1)) >= ShadowValue
469  return IRB.CreateICmpSGE(LastAccessedByte, ShadowValue);
470}
471
472void AddressSanitizer::instrumentAddress(AsanFunctionContext &AFC,
473                                         Instruction *OrigIns,
474                                         IRBuilder<> &IRB, Value *Addr,
475                                         uint32_t TypeSize, bool IsWrite) {
476  Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
477
478  Type *ShadowTy  = IntegerType::get(
479      *C, std::max(8U, TypeSize >> MappingScale));
480  Type *ShadowPtrTy = PointerType::get(ShadowTy, 0);
481  Value *ShadowPtr = memToShadow(AddrLong, IRB);
482  Value *CmpVal = Constant::getNullValue(ShadowTy);
483  Value *ShadowValue = IRB.CreateLoad(
484      IRB.CreateIntToPtr(ShadowPtr, ShadowPtrTy));
485
486  Value *Cmp = IRB.CreateICmpNE(ShadowValue, CmpVal);
487  size_t AccessSizeIndex = TypeSizeToSizeIndex(TypeSize);
488  size_t Granularity = 1 << MappingScale;
489  TerminatorInst *CrashTerm = 0;
490
491  if (ClAlwaysSlowPath || (TypeSize < 8 * Granularity)) {
492    TerminatorInst *CheckTerm = splitBlockAndInsertIfThen(Cmp, false);
493    assert(dyn_cast<BranchInst>(CheckTerm)->isUnconditional());
494    BasicBlock *NextBB = CheckTerm->getSuccessor(0);
495    IRB.SetInsertPoint(CheckTerm);
496    Value *Cmp2 = createSlowPathCmp(IRB, AddrLong, ShadowValue, TypeSize);
497    BasicBlock *CrashBlock = BasicBlock::Create(*C, "", &AFC.F, NextBB);
498    CrashTerm = new UnreachableInst(*C, CrashBlock);
499    BranchInst *NewTerm = BranchInst::Create(CrashBlock, NextBB, Cmp2);
500    ReplaceInstWithInst(CheckTerm, NewTerm);
501  } else {
502    CrashTerm = splitBlockAndInsertIfThen(Cmp, true);
503  }
504
505  Instruction *Crash =
506      generateCrashCode(CrashTerm, AddrLong, IsWrite, AccessSizeIndex);
507  Crash->setDebugLoc(OrigIns->getDebugLoc());
508}
509
510void AddressSanitizer::createInitializerPoisonCalls(Module &M,
511                                                    Value *FirstAddr,
512                                                    Value *LastAddr) {
513  // We do all of our poisoning and unpoisoning within _GLOBAL__I_a.
514  Function *GlobalInit = M.getFunction("_GLOBAL__I_a");
515  // If that function is not present, this TU contains no globals, or they have
516  // all been optimized away
517  if (!GlobalInit)
518    return;
519
520  // Set up the arguments to our poison/unpoison functions.
521  IRBuilder<> IRB(GlobalInit->begin()->getFirstInsertionPt());
522
523  // Declare our poisoning and unpoisoning functions.
524  Function *AsanPoisonGlobals = checkInterfaceFunction(M.getOrInsertFunction(
525      kAsanPoisonGlobalsName, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
526  AsanPoisonGlobals->setLinkage(Function::ExternalLinkage);
527  Function *AsanUnpoisonGlobals = checkInterfaceFunction(M.getOrInsertFunction(
528      kAsanUnpoisonGlobalsName, IRB.getVoidTy(), NULL));
529  AsanUnpoisonGlobals->setLinkage(Function::ExternalLinkage);
530
531  // Add a call to poison all external globals before the given function starts.
532  IRB.CreateCall2(AsanPoisonGlobals, FirstAddr, LastAddr);
533
534  // Add calls to unpoison all globals before each return instruction.
535  for (Function::iterator I = GlobalInit->begin(), E = GlobalInit->end();
536      I != E; ++I) {
537    if (ReturnInst *RI = dyn_cast<ReturnInst>(I->getTerminator())) {
538      CallInst::Create(AsanUnpoisonGlobals, "", RI);
539    }
540  }
541}
542
543bool AddressSanitizer::ShouldInstrumentGlobal(GlobalVariable *G) {
544  Type *Ty = cast<PointerType>(G->getType())->getElementType();
545  DEBUG(dbgs() << "GLOBAL: " << *G);
546
547  if (BL->isIn(*G)) return false;
548  if (!Ty->isSized()) return false;
549  if (!G->hasInitializer()) return false;
550  // Touch only those globals that will not be defined in other modules.
551  // Don't handle ODR type linkages since other modules may be built w/o asan.
552  if (G->getLinkage() != GlobalVariable::ExternalLinkage &&
553      G->getLinkage() != GlobalVariable::PrivateLinkage &&
554      G->getLinkage() != GlobalVariable::InternalLinkage)
555    return false;
556  // Two problems with thread-locals:
557  //   - The address of the main thread's copy can't be computed at link-time.
558  //   - Need to poison all copies, not just the main thread's one.
559  if (G->isThreadLocal())
560    return false;
561  // For now, just ignore this Alloca if the alignment is large.
562  if (G->getAlignment() > RedzoneSize) return false;
563
564  // Ignore all the globals with the names starting with "\01L_OBJC_".
565  // Many of those are put into the .cstring section. The linker compresses
566  // that section by removing the spare \0s after the string terminator, so
567  // our redzones get broken.
568  if ((G->getName().find("\01L_OBJC_") == 0) ||
569      (G->getName().find("\01l_OBJC_") == 0)) {
570    DEBUG(dbgs() << "Ignoring \\01L_OBJC_* global: " << *G);
571    return false;
572  }
573
574  if (G->hasSection()) {
575    StringRef Section(G->getSection());
576    // Ignore the globals from the __OBJC section. The ObjC runtime assumes
577    // those conform to /usr/lib/objc/runtime.h, so we can't add redzones to
578    // them.
579    if ((Section.find("__OBJC,") == 0) ||
580        (Section.find("__DATA, __objc_") == 0)) {
581      DEBUG(dbgs() << "Ignoring ObjC runtime global: " << *G);
582      return false;
583    }
584    // See http://code.google.com/p/address-sanitizer/issues/detail?id=32
585    // Constant CFString instances are compiled in the following way:
586    //  -- the string buffer is emitted into
587    //     __TEXT,__cstring,cstring_literals
588    //  -- the constant NSConstantString structure referencing that buffer
589    //     is placed into __DATA,__cfstring
590    // Therefore there's no point in placing redzones into __DATA,__cfstring.
591    // Moreover, it causes the linker to crash on OS X 10.7
592    if (Section.find("__DATA,__cfstring") == 0) {
593      DEBUG(dbgs() << "Ignoring CFString: " << *G);
594      return false;
595    }
596  }
597
598  return true;
599}
600
601// This function replaces all global variables with new variables that have
602// trailing redzones. It also creates a function that poisons
603// redzones and inserts this function into llvm.global_ctors.
604bool AddressSanitizer::insertGlobalRedzones(Module &M) {
605  SmallVector<GlobalVariable *, 16> GlobalsToChange;
606
607  for (Module::GlobalListType::iterator G = M.global_begin(),
608       E = M.global_end(); G != E; ++G) {
609    if (ShouldInstrumentGlobal(G))
610      GlobalsToChange.push_back(G);
611  }
612
613  size_t n = GlobalsToChange.size();
614  if (n == 0) return false;
615
616  // A global is described by a structure
617  //   size_t beg;
618  //   size_t size;
619  //   size_t size_with_redzone;
620  //   const char *name;
621  //   size_t has_dynamic_init;
622  // We initialize an array of such structures and pass it to a run-time call.
623  StructType *GlobalStructTy = StructType::get(IntptrTy, IntptrTy,
624                                               IntptrTy, IntptrTy,
625                                               IntptrTy, NULL);
626  SmallVector<Constant *, 16> Initializers(n), DynamicInit;
627
628  IRBuilder<> IRB(CtorInsertBefore);
629
630  if (ClInitializers)
631    FindDynamicInitializers(M);
632
633  // The addresses of the first and last dynamically initialized globals in
634  // this TU.  Used in initialization order checking.
635  Value *FirstDynamic = 0, *LastDynamic = 0;
636
637  for (size_t i = 0; i < n; i++) {
638    GlobalVariable *G = GlobalsToChange[i];
639    PointerType *PtrTy = cast<PointerType>(G->getType());
640    Type *Ty = PtrTy->getElementType();
641    uint64_t SizeInBytes = TD->getTypeAllocSize(Ty);
642    uint64_t RightRedzoneSize = RedzoneSize +
643        (RedzoneSize - (SizeInBytes % RedzoneSize));
644    Type *RightRedZoneTy = ArrayType::get(IRB.getInt8Ty(), RightRedzoneSize);
645    // Determine whether this global should be poisoned in initialization.
646    bool GlobalHasDynamicInitializer = HasDynamicInitializer(G);
647    // Don't check initialization order if this global is blacklisted.
648    GlobalHasDynamicInitializer &= !BL->isInInit(*G);
649
650    StructType *NewTy = StructType::get(Ty, RightRedZoneTy, NULL);
651    Constant *NewInitializer = ConstantStruct::get(
652        NewTy, G->getInitializer(),
653        Constant::getNullValue(RightRedZoneTy), NULL);
654
655    SmallString<2048> DescriptionOfGlobal = G->getName();
656    DescriptionOfGlobal += " (";
657    DescriptionOfGlobal += M.getModuleIdentifier();
658    DescriptionOfGlobal += ")";
659    GlobalVariable *Name = createPrivateGlobalForString(M, DescriptionOfGlobal);
660
661    // Create a new global variable with enough space for a redzone.
662    GlobalVariable *NewGlobal = new GlobalVariable(
663        M, NewTy, G->isConstant(), G->getLinkage(),
664        NewInitializer, "", G, G->getThreadLocalMode());
665    NewGlobal->copyAttributesFrom(G);
666    NewGlobal->setAlignment(RedzoneSize);
667
668    Value *Indices2[2];
669    Indices2[0] = IRB.getInt32(0);
670    Indices2[1] = IRB.getInt32(0);
671
672    G->replaceAllUsesWith(
673        ConstantExpr::getGetElementPtr(NewGlobal, Indices2, true));
674    NewGlobal->takeName(G);
675    G->eraseFromParent();
676
677    Initializers[i] = ConstantStruct::get(
678        GlobalStructTy,
679        ConstantExpr::getPointerCast(NewGlobal, IntptrTy),
680        ConstantInt::get(IntptrTy, SizeInBytes),
681        ConstantInt::get(IntptrTy, SizeInBytes + RightRedzoneSize),
682        ConstantExpr::getPointerCast(Name, IntptrTy),
683        ConstantInt::get(IntptrTy, GlobalHasDynamicInitializer),
684        NULL);
685
686    // Populate the first and last globals declared in this TU.
687    if (ClInitializers && GlobalHasDynamicInitializer) {
688      LastDynamic = ConstantExpr::getPointerCast(NewGlobal, IntptrTy);
689      if (FirstDynamic == 0)
690        FirstDynamic = LastDynamic;
691    }
692
693    DEBUG(dbgs() << "NEW GLOBAL:\n" << *NewGlobal);
694  }
695
696  ArrayType *ArrayOfGlobalStructTy = ArrayType::get(GlobalStructTy, n);
697  GlobalVariable *AllGlobals = new GlobalVariable(
698      M, ArrayOfGlobalStructTy, false, GlobalVariable::PrivateLinkage,
699      ConstantArray::get(ArrayOfGlobalStructTy, Initializers), "");
700
701  // Create calls for poisoning before initializers run and unpoisoning after.
702  if (ClInitializers && FirstDynamic && LastDynamic)
703    createInitializerPoisonCalls(M, FirstDynamic, LastDynamic);
704
705  Function *AsanRegisterGlobals = checkInterfaceFunction(M.getOrInsertFunction(
706      kAsanRegisterGlobalsName, IRB.getVoidTy(),
707      IntptrTy, IntptrTy, NULL));
708  AsanRegisterGlobals->setLinkage(Function::ExternalLinkage);
709
710  IRB.CreateCall2(AsanRegisterGlobals,
711                  IRB.CreatePointerCast(AllGlobals, IntptrTy),
712                  ConstantInt::get(IntptrTy, n));
713
714  // We also need to unregister globals at the end, e.g. when a shared library
715  // gets closed.
716  Function *AsanDtorFunction = Function::Create(
717      FunctionType::get(Type::getVoidTy(*C), false),
718      GlobalValue::InternalLinkage, kAsanModuleDtorName, &M);
719  BasicBlock *AsanDtorBB = BasicBlock::Create(*C, "", AsanDtorFunction);
720  IRBuilder<> IRB_Dtor(ReturnInst::Create(*C, AsanDtorBB));
721  Function *AsanUnregisterGlobals =
722      checkInterfaceFunction(M.getOrInsertFunction(
723          kAsanUnregisterGlobalsName,
724          IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
725  AsanUnregisterGlobals->setLinkage(Function::ExternalLinkage);
726
727  IRB_Dtor.CreateCall2(AsanUnregisterGlobals,
728                       IRB.CreatePointerCast(AllGlobals, IntptrTy),
729                       ConstantInt::get(IntptrTy, n));
730  appendToGlobalDtors(M, AsanDtorFunction, kAsanCtorAndCtorPriority);
731
732  DEBUG(dbgs() << M);
733  return true;
734}
735
736// virtual
737bool AddressSanitizer::runOnModule(Module &M) {
738  // Initialize the private fields. No one has accessed them before.
739  TD = getAnalysisIfAvailable<TargetData>();
740  if (!TD)
741    return false;
742  BL.reset(new BlackList(ClBlackListFile));
743
744  C = &(M.getContext());
745  LongSize = TD->getPointerSizeInBits();
746  IntptrTy = Type::getIntNTy(*C, LongSize);
747  IntptrPtrTy = PointerType::get(IntptrTy, 0);
748
749  AsanCtorFunction = Function::Create(
750      FunctionType::get(Type::getVoidTy(*C), false),
751      GlobalValue::InternalLinkage, kAsanModuleCtorName, &M);
752  BasicBlock *AsanCtorBB = BasicBlock::Create(*C, "", AsanCtorFunction);
753  CtorInsertBefore = ReturnInst::Create(*C, AsanCtorBB);
754
755  // call __asan_init in the module ctor.
756  IRBuilder<> IRB(CtorInsertBefore);
757  AsanInitFunction = checkInterfaceFunction(
758      M.getOrInsertFunction(kAsanInitName, IRB.getVoidTy(), NULL));
759  AsanInitFunction->setLinkage(Function::ExternalLinkage);
760  IRB.CreateCall(AsanInitFunction);
761
762  // Create __asan_report* callbacks.
763  for (size_t AccessIsWrite = 0; AccessIsWrite <= 1; AccessIsWrite++) {
764    for (size_t AccessSizeIndex = 0; AccessSizeIndex < kNumberOfAccessSizes;
765         AccessSizeIndex++) {
766      // IsWrite and TypeSize are encoded in the function name.
767      std::string FunctionName = std::string(kAsanReportErrorTemplate) +
768          (AccessIsWrite ? "store" : "load") + itostr(1 << AccessSizeIndex);
769      // If we are merging crash callbacks, they have two parameters.
770      AsanErrorCallback[AccessIsWrite][AccessSizeIndex] = cast<Function>(
771          M.getOrInsertFunction(FunctionName, IRB.getVoidTy(), IntptrTy, NULL));
772    }
773  }
774  // We insert an empty inline asm after __asan_report* to avoid callback merge.
775  EmptyAsm = InlineAsm::get(FunctionType::get(IRB.getVoidTy(), false),
776                            StringRef(""), StringRef(""),
777                            /*hasSideEffects=*/true);
778
779  llvm::Triple targetTriple(M.getTargetTriple());
780  bool isAndroid = targetTriple.getEnvironment() == llvm::Triple::Android;
781
782  MappingOffset = isAndroid ? kDefaultShadowOffsetAndroid :
783    (LongSize == 32 ? kDefaultShadowOffset32 : kDefaultShadowOffset64);
784  if (ClMappingOffsetLog >= 0) {
785    if (ClMappingOffsetLog == 0) {
786      // special case
787      MappingOffset = 0;
788    } else {
789      MappingOffset = 1ULL << ClMappingOffsetLog;
790    }
791  }
792  MappingScale = kDefaultShadowScale;
793  if (ClMappingScale) {
794    MappingScale = ClMappingScale;
795  }
796  // Redzone used for stack and globals is at least 32 bytes.
797  // For scales 6 and 7, the redzone has to be 64 and 128 bytes respectively.
798  RedzoneSize = std::max(32, (int)(1 << MappingScale));
799
800  bool Res = false;
801
802  if (ClGlobals)
803    Res |= insertGlobalRedzones(M);
804
805  if (ClMappingOffsetLog >= 0) {
806    // Tell the run-time the current values of mapping offset and scale.
807    GlobalValue *asan_mapping_offset =
808        new GlobalVariable(M, IntptrTy, true, GlobalValue::LinkOnceODRLinkage,
809                       ConstantInt::get(IntptrTy, MappingOffset),
810                       kAsanMappingOffsetName);
811    // Read the global, otherwise it may be optimized away.
812    IRB.CreateLoad(asan_mapping_offset, true);
813  }
814  if (ClMappingScale) {
815    GlobalValue *asan_mapping_scale =
816        new GlobalVariable(M, IntptrTy, true, GlobalValue::LinkOnceODRLinkage,
817                           ConstantInt::get(IntptrTy, MappingScale),
818                           kAsanMappingScaleName);
819    // Read the global, otherwise it may be optimized away.
820    IRB.CreateLoad(asan_mapping_scale, true);
821  }
822
823
824  for (Module::iterator F = M.begin(), E = M.end(); F != E; ++F) {
825    if (F->isDeclaration()) continue;
826    Res |= handleFunction(M, *F);
827  }
828
829  appendToGlobalCtors(M, AsanCtorFunction, kAsanCtorAndCtorPriority);
830
831  return Res;
832}
833
834bool AddressSanitizer::maybeInsertAsanInitAtFunctionEntry(Function &F) {
835  // For each NSObject descendant having a +load method, this method is invoked
836  // by the ObjC runtime before any of the static constructors is called.
837  // Therefore we need to instrument such methods with a call to __asan_init
838  // at the beginning in order to initialize our runtime before any access to
839  // the shadow memory.
840  // We cannot just ignore these methods, because they may call other
841  // instrumented functions.
842  if (F.getName().find(" load]") != std::string::npos) {
843    IRBuilder<> IRB(F.begin()->begin());
844    IRB.CreateCall(AsanInitFunction);
845    return true;
846  }
847  return false;
848}
849
850bool AddressSanitizer::handleFunction(Module &M, Function &F) {
851  if (BL->isIn(F)) return false;
852  if (&F == AsanCtorFunction) return false;
853
854  // If needed, insert __asan_init before checking for AddressSafety attr.
855  maybeInsertAsanInitAtFunctionEntry(F);
856
857  if (!F.hasFnAttr(Attribute::AddressSafety)) return false;
858
859  if (!ClDebugFunc.empty() && ClDebugFunc != F.getName())
860    return false;
861  // We want to instrument every address only once per basic block
862  // (unless there are calls between uses).
863  SmallSet<Value*, 16> TempsToInstrument;
864  SmallVector<Instruction*, 16> ToInstrument;
865  SmallVector<Instruction*, 8> NoReturnCalls;
866  bool IsWrite;
867
868  // Fill the set of memory operations to instrument.
869  for (Function::iterator FI = F.begin(), FE = F.end();
870       FI != FE; ++FI) {
871    TempsToInstrument.clear();
872    int NumInsnsPerBB = 0;
873    for (BasicBlock::iterator BI = FI->begin(), BE = FI->end();
874         BI != BE; ++BI) {
875      if (LooksLikeCodeInBug11395(BI)) return false;
876      if (Value *Addr = isInterestingMemoryAccess(BI, &IsWrite)) {
877        if (ClOpt && ClOptSameTemp) {
878          if (!TempsToInstrument.insert(Addr))
879            continue;  // We've seen this temp in the current BB.
880        }
881      } else if (isa<MemIntrinsic>(BI) && ClMemIntrin) {
882        // ok, take it.
883      } else {
884        if (CallInst *CI = dyn_cast<CallInst>(BI)) {
885          // A call inside BB.
886          TempsToInstrument.clear();
887          if (CI->doesNotReturn()) {
888            NoReturnCalls.push_back(CI);
889          }
890        }
891        continue;
892      }
893      ToInstrument.push_back(BI);
894      NumInsnsPerBB++;
895      if (NumInsnsPerBB >= ClMaxInsnsToInstrumentPerBB)
896        break;
897    }
898  }
899
900  AsanFunctionContext AFC(F);
901
902  // Instrument.
903  int NumInstrumented = 0;
904  for (size_t i = 0, n = ToInstrument.size(); i != n; i++) {
905    Instruction *Inst = ToInstrument[i];
906    if (ClDebugMin < 0 || ClDebugMax < 0 ||
907        (NumInstrumented >= ClDebugMin && NumInstrumented <= ClDebugMax)) {
908      if (isInterestingMemoryAccess(Inst, &IsWrite))
909        instrumentMop(AFC, Inst);
910      else
911        instrumentMemIntrinsic(AFC, cast<MemIntrinsic>(Inst));
912    }
913    NumInstrumented++;
914  }
915
916  DEBUG(dbgs() << F);
917
918  bool ChangedStack = poisonStackInFunction(M, F);
919
920  // We must unpoison the stack before every NoReturn call (throw, _exit, etc).
921  // See e.g. http://code.google.com/p/address-sanitizer/issues/detail?id=37
922  for (size_t i = 0, n = NoReturnCalls.size(); i != n; i++) {
923    Instruction *CI = NoReturnCalls[i];
924    IRBuilder<> IRB(CI);
925    IRB.CreateCall(M.getOrInsertFunction(kAsanHandleNoReturnName,
926                                         IRB.getVoidTy(), NULL));
927  }
928
929  return NumInstrumented > 0 || ChangedStack || !NoReturnCalls.empty();
930}
931
932static uint64_t ValueForPoison(uint64_t PoisonByte, size_t ShadowRedzoneSize) {
933  if (ShadowRedzoneSize == 1) return PoisonByte;
934  if (ShadowRedzoneSize == 2) return (PoisonByte << 8) + PoisonByte;
935  if (ShadowRedzoneSize == 4)
936    return (PoisonByte << 24) + (PoisonByte << 16) +
937        (PoisonByte << 8) + (PoisonByte);
938  llvm_unreachable("ShadowRedzoneSize is either 1, 2 or 4");
939}
940
941static void PoisonShadowPartialRightRedzone(uint8_t *Shadow,
942                                            size_t Size,
943                                            size_t RedzoneSize,
944                                            size_t ShadowGranularity,
945                                            uint8_t Magic) {
946  for (size_t i = 0; i < RedzoneSize;
947       i+= ShadowGranularity, Shadow++) {
948    if (i + ShadowGranularity <= Size) {
949      *Shadow = 0;  // fully addressable
950    } else if (i >= Size) {
951      *Shadow = Magic;  // unaddressable
952    } else {
953      *Shadow = Size - i;  // first Size-i bytes are addressable
954    }
955  }
956}
957
958void AddressSanitizer::PoisonStack(const ArrayRef<AllocaInst*> &AllocaVec,
959                                   IRBuilder<> IRB,
960                                   Value *ShadowBase, bool DoPoison) {
961  size_t ShadowRZSize = RedzoneSize >> MappingScale;
962  assert(ShadowRZSize >= 1 && ShadowRZSize <= 4);
963  Type *RZTy = Type::getIntNTy(*C, ShadowRZSize * 8);
964  Type *RZPtrTy = PointerType::get(RZTy, 0);
965
966  Value *PoisonLeft  = ConstantInt::get(RZTy,
967    ValueForPoison(DoPoison ? kAsanStackLeftRedzoneMagic : 0LL, ShadowRZSize));
968  Value *PoisonMid   = ConstantInt::get(RZTy,
969    ValueForPoison(DoPoison ? kAsanStackMidRedzoneMagic : 0LL, ShadowRZSize));
970  Value *PoisonRight = ConstantInt::get(RZTy,
971    ValueForPoison(DoPoison ? kAsanStackRightRedzoneMagic : 0LL, ShadowRZSize));
972
973  // poison the first red zone.
974  IRB.CreateStore(PoisonLeft, IRB.CreateIntToPtr(ShadowBase, RZPtrTy));
975
976  // poison all other red zones.
977  uint64_t Pos = RedzoneSize;
978  for (size_t i = 0, n = AllocaVec.size(); i < n; i++) {
979    AllocaInst *AI = AllocaVec[i];
980    uint64_t SizeInBytes = getAllocaSizeInBytes(AI);
981    uint64_t AlignedSize = getAlignedAllocaSize(AI);
982    assert(AlignedSize - SizeInBytes < RedzoneSize);
983    Value *Ptr = NULL;
984
985    Pos += AlignedSize;
986
987    assert(ShadowBase->getType() == IntptrTy);
988    if (SizeInBytes < AlignedSize) {
989      // Poison the partial redzone at right
990      Ptr = IRB.CreateAdd(
991          ShadowBase, ConstantInt::get(IntptrTy,
992                                       (Pos >> MappingScale) - ShadowRZSize));
993      size_t AddressableBytes = RedzoneSize - (AlignedSize - SizeInBytes);
994      uint32_t Poison = 0;
995      if (DoPoison) {
996        PoisonShadowPartialRightRedzone((uint8_t*)&Poison, AddressableBytes,
997                                        RedzoneSize,
998                                        1ULL << MappingScale,
999                                        kAsanStackPartialRedzoneMagic);
1000      }
1001      Value *PartialPoison = ConstantInt::get(RZTy, Poison);
1002      IRB.CreateStore(PartialPoison, IRB.CreateIntToPtr(Ptr, RZPtrTy));
1003    }
1004
1005    // Poison the full redzone at right.
1006    Ptr = IRB.CreateAdd(ShadowBase,
1007                        ConstantInt::get(IntptrTy, Pos >> MappingScale));
1008    Value *Poison = i == AllocaVec.size() - 1 ? PoisonRight : PoisonMid;
1009    IRB.CreateStore(Poison, IRB.CreateIntToPtr(Ptr, RZPtrTy));
1010
1011    Pos += RedzoneSize;
1012  }
1013}
1014
1015// Workaround for bug 11395: we don't want to instrument stack in functions
1016// with large assembly blobs (32-bit only), otherwise reg alloc may crash.
1017// FIXME: remove once the bug 11395 is fixed.
1018bool AddressSanitizer::LooksLikeCodeInBug11395(Instruction *I) {
1019  if (LongSize != 32) return false;
1020  CallInst *CI = dyn_cast<CallInst>(I);
1021  if (!CI || !CI->isInlineAsm()) return false;
1022  if (CI->getNumArgOperands() <= 5) return false;
1023  // We have inline assembly with quite a few arguments.
1024  return true;
1025}
1026
1027// Find all static Alloca instructions and put
1028// poisoned red zones around all of them.
1029// Then unpoison everything back before the function returns.
1030//
1031// Stack poisoning does not play well with exception handling.
1032// When an exception is thrown, we essentially bypass the code
1033// that unpoisones the stack. This is why the run-time library has
1034// to intercept __cxa_throw (as well as longjmp, etc) and unpoison the entire
1035// stack in the interceptor. This however does not work inside the
1036// actual function which catches the exception. Most likely because the
1037// compiler hoists the load of the shadow value somewhere too high.
1038// This causes asan to report a non-existing bug on 453.povray.
1039// It sounds like an LLVM bug.
1040bool AddressSanitizer::poisonStackInFunction(Module &M, Function &F) {
1041  if (!ClStack) return false;
1042  SmallVector<AllocaInst*, 16> AllocaVec;
1043  SmallVector<Instruction*, 8> RetVec;
1044  uint64_t TotalSize = 0;
1045
1046  // Filter out Alloca instructions we want (and can) handle.
1047  // Collect Ret instructions.
1048  for (Function::iterator FI = F.begin(), FE = F.end();
1049       FI != FE; ++FI) {
1050    BasicBlock &BB = *FI;
1051    for (BasicBlock::iterator BI = BB.begin(), BE = BB.end();
1052         BI != BE; ++BI) {
1053      if (isa<ReturnInst>(BI)) {
1054          RetVec.push_back(BI);
1055          continue;
1056      }
1057
1058      AllocaInst *AI = dyn_cast<AllocaInst>(BI);
1059      if (!AI) continue;
1060      if (AI->isArrayAllocation()) continue;
1061      if (!AI->isStaticAlloca()) continue;
1062      if (!AI->getAllocatedType()->isSized()) continue;
1063      if (AI->getAlignment() > RedzoneSize) continue;
1064      AllocaVec.push_back(AI);
1065      uint64_t AlignedSize =  getAlignedAllocaSize(AI);
1066      TotalSize += AlignedSize;
1067    }
1068  }
1069
1070  if (AllocaVec.empty()) return false;
1071
1072  uint64_t LocalStackSize = TotalSize + (AllocaVec.size() + 1) * RedzoneSize;
1073
1074  bool DoStackMalloc = ClUseAfterReturn
1075      && LocalStackSize <= kMaxStackMallocSize;
1076
1077  Instruction *InsBefore = AllocaVec[0];
1078  IRBuilder<> IRB(InsBefore);
1079
1080
1081  Type *ByteArrayTy = ArrayType::get(IRB.getInt8Ty(), LocalStackSize);
1082  AllocaInst *MyAlloca =
1083      new AllocaInst(ByteArrayTy, "MyAlloca", InsBefore);
1084  MyAlloca->setAlignment(RedzoneSize);
1085  assert(MyAlloca->isStaticAlloca());
1086  Value *OrigStackBase = IRB.CreatePointerCast(MyAlloca, IntptrTy);
1087  Value *LocalStackBase = OrigStackBase;
1088
1089  if (DoStackMalloc) {
1090    Value *AsanStackMallocFunc = M.getOrInsertFunction(
1091        kAsanStackMallocName, IntptrTy, IntptrTy, IntptrTy, NULL);
1092    LocalStackBase = IRB.CreateCall2(AsanStackMallocFunc,
1093        ConstantInt::get(IntptrTy, LocalStackSize), OrigStackBase);
1094  }
1095
1096  // This string will be parsed by the run-time (DescribeStackAddress).
1097  SmallString<2048> StackDescriptionStorage;
1098  raw_svector_ostream StackDescription(StackDescriptionStorage);
1099  StackDescription << F.getName() << " " << AllocaVec.size() << " ";
1100
1101  uint64_t Pos = RedzoneSize;
1102  // Replace Alloca instructions with base+offset.
1103  for (size_t i = 0, n = AllocaVec.size(); i < n; i++) {
1104    AllocaInst *AI = AllocaVec[i];
1105    uint64_t SizeInBytes = getAllocaSizeInBytes(AI);
1106    StringRef Name = AI->getName();
1107    StackDescription << Pos << " " << SizeInBytes << " "
1108                     << Name.size() << " " << Name << " ";
1109    uint64_t AlignedSize = getAlignedAllocaSize(AI);
1110    assert((AlignedSize % RedzoneSize) == 0);
1111    AI->replaceAllUsesWith(
1112        IRB.CreateIntToPtr(
1113            IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy, Pos)),
1114            AI->getType()));
1115    Pos += AlignedSize + RedzoneSize;
1116  }
1117  assert(Pos == LocalStackSize);
1118
1119  // Write the Magic value and the frame description constant to the redzone.
1120  Value *BasePlus0 = IRB.CreateIntToPtr(LocalStackBase, IntptrPtrTy);
1121  IRB.CreateStore(ConstantInt::get(IntptrTy, kCurrentStackFrameMagic),
1122                  BasePlus0);
1123  Value *BasePlus1 = IRB.CreateAdd(LocalStackBase,
1124                                   ConstantInt::get(IntptrTy, LongSize/8));
1125  BasePlus1 = IRB.CreateIntToPtr(BasePlus1, IntptrPtrTy);
1126  Value *Description = IRB.CreatePointerCast(
1127      createPrivateGlobalForString(M, StackDescription.str()),
1128      IntptrTy);
1129  IRB.CreateStore(Description, BasePlus1);
1130
1131  // Poison the stack redzones at the entry.
1132  Value *ShadowBase = memToShadow(LocalStackBase, IRB);
1133  PoisonStack(ArrayRef<AllocaInst*>(AllocaVec), IRB, ShadowBase, true);
1134
1135  Value *AsanStackFreeFunc = NULL;
1136  if (DoStackMalloc) {
1137    AsanStackFreeFunc = M.getOrInsertFunction(
1138        kAsanStackFreeName, IRB.getVoidTy(),
1139        IntptrTy, IntptrTy, IntptrTy, NULL);
1140  }
1141
1142  // Unpoison the stack before all ret instructions.
1143  for (size_t i = 0, n = RetVec.size(); i < n; i++) {
1144    Instruction *Ret = RetVec[i];
1145    IRBuilder<> IRBRet(Ret);
1146
1147    // Mark the current frame as retired.
1148    IRBRet.CreateStore(ConstantInt::get(IntptrTy, kRetiredStackFrameMagic),
1149                       BasePlus0);
1150    // Unpoison the stack.
1151    PoisonStack(ArrayRef<AllocaInst*>(AllocaVec), IRBRet, ShadowBase, false);
1152
1153    if (DoStackMalloc) {
1154      IRBRet.CreateCall3(AsanStackFreeFunc, LocalStackBase,
1155                         ConstantInt::get(IntptrTy, LocalStackSize),
1156                         OrigStackBase);
1157    }
1158  }
1159
1160  if (ClDebugStack) {
1161    DEBUG(dbgs() << F);
1162  }
1163
1164  return true;
1165}
1166