1 //===-- AddressSanitizer.cpp - memory error detector ------------*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
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
14 //===----------------------------------------------------------------------===//
16 #define DEBUG_TYPE "asan"
18 #include "llvm/Transforms/Instrumentation.h"
19 #include "BlackList.h"
20 #include "llvm/ADT/ArrayRef.h"
21 #include "llvm/ADT/OwningPtr.h"
22 #include "llvm/ADT/SmallSet.h"
23 #include "llvm/ADT/SmallString.h"
24 #include "llvm/ADT/SmallVector.h"
25 #include "llvm/ADT/StringExtras.h"
26 #include "llvm/ADT/Triple.h"
27 #include "llvm/DataLayout.h"
28 #include "llvm/DIBuilder.h"
29 #include "llvm/Function.h"
30 #include "llvm/IRBuilder.h"
31 #include "llvm/InlineAsm.h"
32 #include "llvm/IntrinsicInst.h"
33 #include "llvm/LLVMContext.h"
34 #include "llvm/Module.h"
35 #include "llvm/Support/CommandLine.h"
36 #include "llvm/Support/DataTypes.h"
37 #include "llvm/Support/Debug.h"
38 #include "llvm/Support/raw_ostream.h"
39 #include "llvm/Support/system_error.h"
40 #include "llvm/Target/TargetMachine.h"
41 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
42 #include "llvm/Transforms/Utils/Local.h"
43 #include "llvm/Transforms/Utils/ModuleUtils.h"
44 #include "llvm/Type.h"
50 static const uint64_t kDefaultShadowScale = 3;
51 static const uint64_t kDefaultShadowOffset32 = 1ULL << 29;
52 static const uint64_t kDefaultShadowOffset64 = 1ULL << 44;
53 static const uint64_t kDefaultShadowOffsetAndroid = 0;
55 static const size_t kMaxStackMallocSize = 1 << 16; // 64K
56 static const uintptr_t kCurrentStackFrameMagic = 0x41B58AB3;
57 static const uintptr_t kRetiredStackFrameMagic = 0x45E0360E;
59 static const char *kAsanModuleCtorName = "asan.module_ctor";
60 static const char *kAsanModuleDtorName = "asan.module_dtor";
61 static const int kAsanCtorAndCtorPriority = 1;
62 static const char *kAsanReportErrorTemplate = "__asan_report_";
63 static const char *kAsanRegisterGlobalsName = "__asan_register_globals";
64 static const char *kAsanUnregisterGlobalsName = "__asan_unregister_globals";
65 static const char *kAsanPoisonGlobalsName = "__asan_before_dynamic_init";
66 static const char *kAsanUnpoisonGlobalsName = "__asan_after_dynamic_init";
67 static const char *kAsanInitName = "__asan_init";
68 static const char *kAsanHandleNoReturnName = "__asan_handle_no_return";
69 static const char *kAsanMappingOffsetName = "__asan_mapping_offset";
70 static const char *kAsanMappingScaleName = "__asan_mapping_scale";
71 static const char *kAsanStackMallocName = "__asan_stack_malloc";
72 static const char *kAsanStackFreeName = "__asan_stack_free";
73 static const char *kAsanGenPrefix = "__asan_gen_";
74 static const char *kAsanPoisonStackMemoryName = "__asan_poison_stack_memory";
75 static const char *kAsanUnpoisonStackMemoryName =
76 "__asan_unpoison_stack_memory";
78 static const int kAsanStackLeftRedzoneMagic = 0xf1;
79 static const int kAsanStackMidRedzoneMagic = 0xf2;
80 static const int kAsanStackRightRedzoneMagic = 0xf3;
81 static const int kAsanStackPartialRedzoneMagic = 0xf4;
83 // Accesses sizes are powers of two: 1, 2, 4, 8, 16.
84 static const size_t kNumberOfAccessSizes = 5;
86 // Command-line flags.
88 // This flag may need to be replaced with -f[no-]asan-reads.
89 static cl::opt<bool> ClInstrumentReads("asan-instrument-reads",
90 cl::desc("instrument read instructions"), cl::Hidden, cl::init(true));
91 static cl::opt<bool> ClInstrumentWrites("asan-instrument-writes",
92 cl::desc("instrument write instructions"), cl::Hidden, cl::init(true));
93 static cl::opt<bool> ClInstrumentAtomics("asan-instrument-atomics",
94 cl::desc("instrument atomic instructions (rmw, cmpxchg)"),
95 cl::Hidden, cl::init(true));
96 static cl::opt<bool> ClAlwaysSlowPath("asan-always-slow-path",
97 cl::desc("use instrumentation with slow path for all accesses"),
98 cl::Hidden, cl::init(false));
99 // This flag limits the number of instructions to be instrumented
100 // in any given BB. Normally, this should be set to unlimited (INT_MAX),
101 // but due to http://llvm.org/bugs/show_bug.cgi?id=12652 we temporary
103 static cl::opt<int> ClMaxInsnsToInstrumentPerBB("asan-max-ins-per-bb",
105 cl::desc("maximal number of instructions to instrument in any given BB"),
107 // This flag may need to be replaced with -f[no]asan-stack.
108 static cl::opt<bool> ClStack("asan-stack",
109 cl::desc("Handle stack memory"), cl::Hidden, cl::init(true));
110 // This flag may need to be replaced with -f[no]asan-use-after-return.
111 static cl::opt<bool> ClUseAfterReturn("asan-use-after-return",
112 cl::desc("Check return-after-free"), cl::Hidden, cl::init(false));
113 // This flag may need to be replaced with -f[no]asan-globals.
114 static cl::opt<bool> ClGlobals("asan-globals",
115 cl::desc("Handle global objects"), cl::Hidden, cl::init(true));
116 static cl::opt<bool> ClInitializers("asan-initialization-order",
117 cl::desc("Handle C++ initializer order"), cl::Hidden, cl::init(false));
118 static cl::opt<bool> ClMemIntrin("asan-memintrin",
119 cl::desc("Handle memset/memcpy/memmove"), cl::Hidden, cl::init(true));
120 static cl::opt<bool> ClRealignStack("asan-realign-stack",
121 cl::desc("Realign stack to 32"), cl::Hidden, cl::init(true));
122 static cl::opt<std::string> ClBlacklistFile("asan-blacklist",
123 cl::desc("File containing the list of objects to ignore "
124 "during instrumentation"), cl::Hidden);
126 // These flags allow to change the shadow mapping.
127 // The shadow mapping looks like
128 // Shadow = (Mem >> scale) + (1 << offset_log)
129 static cl::opt<int> ClMappingScale("asan-mapping-scale",
130 cl::desc("scale of asan shadow mapping"), cl::Hidden, cl::init(0));
131 static cl::opt<int> ClMappingOffsetLog("asan-mapping-offset-log",
132 cl::desc("offset of asan shadow mapping"), cl::Hidden, cl::init(-1));
134 // Optimization flags. Not user visible, used mostly for testing
135 // and benchmarking the tool.
136 static cl::opt<bool> ClOpt("asan-opt",
137 cl::desc("Optimize instrumentation"), cl::Hidden, cl::init(true));
138 static cl::opt<bool> ClOptSameTemp("asan-opt-same-temp",
139 cl::desc("Instrument the same temp just once"), cl::Hidden,
141 static cl::opt<bool> ClOptGlobals("asan-opt-globals",
142 cl::desc("Don't instrument scalar globals"), cl::Hidden, cl::init(true));
144 static cl::opt<bool> ClCheckLifetime("asan-check-lifetime",
145 cl::desc("Use llvm.lifetime intrinsics to insert extra checks"),
146 cl::Hidden, cl::init(false));
149 static cl::opt<int> ClDebug("asan-debug", cl::desc("debug"), cl::Hidden,
151 static cl::opt<int> ClDebugStack("asan-debug-stack", cl::desc("debug stack"),
152 cl::Hidden, cl::init(0));
153 static cl::opt<std::string> ClDebugFunc("asan-debug-func",
154 cl::Hidden, cl::desc("Debug func"));
155 static cl::opt<int> ClDebugMin("asan-debug-min", cl::desc("Debug min inst"),
156 cl::Hidden, cl::init(-1));
157 static cl::opt<int> ClDebugMax("asan-debug-max", cl::desc("Debug man inst"),
158 cl::Hidden, cl::init(-1));
161 /// A set of dynamically initialized globals extracted from metadata.
162 class SetOfDynamicallyInitializedGlobals {
164 void Init(Module& M) {
165 // Clang generates metadata identifying all dynamically initialized globals.
166 NamedMDNode *DynamicGlobals =
167 M.getNamedMetadata("llvm.asan.dynamically_initialized_globals");
170 for (int i = 0, n = DynamicGlobals->getNumOperands(); i < n; ++i) {
171 MDNode *MDN = DynamicGlobals->getOperand(i);
172 assert(MDN->getNumOperands() == 1);
173 Value *VG = MDN->getOperand(0);
174 // The optimizer may optimize away a global entirely, in which case we
175 // cannot instrument access to it.
178 DynInitGlobals.insert(cast<GlobalVariable>(VG));
181 bool Contains(GlobalVariable *G) { return DynInitGlobals.count(G) != 0; }
183 SmallSet<GlobalValue*, 32> DynInitGlobals;
186 static int MappingScale() {
187 return ClMappingScale ? ClMappingScale : kDefaultShadowScale;
190 static size_t RedzoneSize() {
191 // Redzone used for stack and globals is at least 32 bytes.
192 // For scales 6 and 7, the redzone has to be 64 and 128 bytes respectively.
193 return std::max(32U, 1U << MappingScale());
196 /// AddressSanitizer: instrument the code in module to find memory bugs.
197 struct AddressSanitizer : public FunctionPass {
198 AddressSanitizer(bool CheckInitOrder = false,
199 bool CheckUseAfterReturn = false,
200 bool CheckLifetime = false,
201 StringRef BlacklistFile = StringRef())
203 CheckInitOrder(CheckInitOrder || ClInitializers),
204 CheckUseAfterReturn(CheckUseAfterReturn || ClUseAfterReturn),
205 CheckLifetime(CheckLifetime || ClCheckLifetime),
206 BlacklistFile(BlacklistFile.empty() ? ClBlacklistFile
208 virtual const char *getPassName() const {
209 return "AddressSanitizerFunctionPass";
211 void instrumentMop(Instruction *I);
212 void instrumentAddress(Instruction *OrigIns, IRBuilder<> &IRB,
213 Value *Addr, uint32_t TypeSize, bool IsWrite);
214 Value *createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
215 Value *ShadowValue, uint32_t TypeSize);
216 Instruction *generateCrashCode(Instruction *InsertBefore, Value *Addr,
217 bool IsWrite, size_t AccessSizeIndex);
218 bool instrumentMemIntrinsic(MemIntrinsic *MI);
219 void instrumentMemIntrinsicParam(Instruction *OrigIns, Value *Addr,
221 Instruction *InsertBefore, bool IsWrite);
222 Value *memToShadow(Value *Shadow, IRBuilder<> &IRB);
223 bool runOnFunction(Function &F);
224 void createInitializerPoisonCalls(Module &M,
225 Value *FirstAddr, Value *LastAddr);
226 bool maybeInsertAsanInitAtFunctionEntry(Function &F);
227 bool poisonStackInFunction(Function &F);
228 virtual bool doInitialization(Module &M);
229 static char ID; // Pass identification, replacement for typeid
232 void initializeCallbacks(Module &M);
233 uint64_t getAllocaSizeInBytes(AllocaInst *AI) {
234 Type *Ty = AI->getAllocatedType();
235 uint64_t SizeInBytes = TD->getTypeAllocSize(Ty);
238 uint64_t getAlignedSize(uint64_t SizeInBytes) {
239 size_t RZ = RedzoneSize();
240 return ((SizeInBytes + RZ - 1) / RZ) * RZ;
242 uint64_t getAlignedAllocaSize(AllocaInst *AI) {
243 uint64_t SizeInBytes = getAllocaSizeInBytes(AI);
244 return getAlignedSize(SizeInBytes);
247 bool ShouldInstrumentGlobal(GlobalVariable *G);
248 void PoisonStack(const ArrayRef<AllocaInst*> &AllocaVec, IRBuilder<> IRB,
249 Value *ShadowBase, bool DoPoison);
250 bool LooksLikeCodeInBug11395(Instruction *I);
251 void FindDynamicInitializers(Module &M);
252 /// Analyze lifetime intrinsics for given alloca. Use Value* instead of
253 /// AllocaInst* here, as we call this method after we merge all allocas into a
254 /// single one. Returns true if ASan added some instrumentation.
255 bool handleAllocaLifetime(Value *Alloca);
256 /// Analyze lifetime intrinsics for a specific value, casted from alloca.
257 /// Returns true if if ASan added some instrumentation.
258 bool handleValueLifetime(Value *V);
259 void poisonAlloca(Value *V, uint64_t Size, IRBuilder<> IRB, bool DoPoison);
262 bool CheckUseAfterReturn;
266 uint64_t MappingOffset;
270 Function *AsanCtorFunction;
271 Function *AsanInitFunction;
272 Function *AsanStackMallocFunc, *AsanStackFreeFunc;
273 Function *AsanPoisonStackMemoryFunc, *AsanUnpoisonStackMemoryFunc;
274 Function *AsanHandleNoReturnFunc;
275 SmallString<64> BlacklistFile;
276 OwningPtr<BlackList> BL;
277 // This array is indexed by AccessIsWrite and log2(AccessSize).
278 Function *AsanErrorCallback[2][kNumberOfAccessSizes];
280 SetOfDynamicallyInitializedGlobals DynamicallyInitializedGlobals;
283 class AddressSanitizerModule : public ModulePass {
285 AddressSanitizerModule(bool CheckInitOrder = false,
286 StringRef BlacklistFile = StringRef())
288 CheckInitOrder(CheckInitOrder || ClInitializers),
289 BlacklistFile(BlacklistFile.empty() ? ClBlacklistFile
291 bool runOnModule(Module &M);
292 static char ID; // Pass identification, replacement for typeid
293 virtual const char *getPassName() const {
294 return "AddressSanitizerModule";
298 bool ShouldInstrumentGlobal(GlobalVariable *G);
299 void createInitializerPoisonCalls(Module &M, Value *FirstAddr,
303 SmallString<64> BlacklistFile;
304 OwningPtr<BlackList> BL;
305 SetOfDynamicallyInitializedGlobals DynamicallyInitializedGlobals;
313 char AddressSanitizer::ID = 0;
314 INITIALIZE_PASS(AddressSanitizer, "asan",
315 "AddressSanitizer: detects use-after-free and out-of-bounds bugs.",
317 FunctionPass *llvm::createAddressSanitizerFunctionPass(
318 bool CheckInitOrder, bool CheckUseAfterReturn, bool CheckLifetime,
319 StringRef BlacklistFile) {
320 return new AddressSanitizer(CheckInitOrder, CheckUseAfterReturn,
321 CheckLifetime, BlacklistFile);
324 char AddressSanitizerModule::ID = 0;
325 INITIALIZE_PASS(AddressSanitizerModule, "asan-module",
326 "AddressSanitizer: detects use-after-free and out-of-bounds bugs."
327 "ModulePass", false, false)
328 ModulePass *llvm::createAddressSanitizerModulePass(
329 bool CheckInitOrder, StringRef BlacklistFile) {
330 return new AddressSanitizerModule(CheckInitOrder, BlacklistFile);
333 static size_t TypeSizeToSizeIndex(uint32_t TypeSize) {
334 size_t Res = CountTrailingZeros_32(TypeSize / 8);
335 assert(Res < kNumberOfAccessSizes);
339 // Create a constant for Str so that we can pass it to the run-time lib.
340 static GlobalVariable *createPrivateGlobalForString(Module &M, StringRef Str) {
341 Constant *StrConst = ConstantDataArray::getString(M.getContext(), Str);
342 return new GlobalVariable(M, StrConst->getType(), true,
343 GlobalValue::PrivateLinkage, StrConst,
347 static bool GlobalWasGeneratedByAsan(GlobalVariable *G) {
348 return G->getName().find(kAsanGenPrefix) == 0;
351 Value *AddressSanitizer::memToShadow(Value *Shadow, IRBuilder<> &IRB) {
353 Shadow = IRB.CreateLShr(Shadow, MappingScale());
354 if (MappingOffset == 0)
356 // (Shadow >> scale) | offset
357 return IRB.CreateOr(Shadow, ConstantInt::get(IntptrTy,
361 void AddressSanitizer::instrumentMemIntrinsicParam(
362 Instruction *OrigIns,
363 Value *Addr, Value *Size, Instruction *InsertBefore, bool IsWrite) {
364 // Check the first byte.
366 IRBuilder<> IRB(InsertBefore);
367 instrumentAddress(OrigIns, IRB, Addr, 8, IsWrite);
369 // Check the last byte.
371 IRBuilder<> IRB(InsertBefore);
372 Value *SizeMinusOne = IRB.CreateSub(
373 Size, ConstantInt::get(Size->getType(), 1));
374 SizeMinusOne = IRB.CreateIntCast(SizeMinusOne, IntptrTy, false);
375 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
376 Value *AddrPlusSizeMinisOne = IRB.CreateAdd(AddrLong, SizeMinusOne);
377 instrumentAddress(OrigIns, IRB, AddrPlusSizeMinisOne, 8, IsWrite);
381 // Instrument memset/memmove/memcpy
382 bool AddressSanitizer::instrumentMemIntrinsic(MemIntrinsic *MI) {
383 Value *Dst = MI->getDest();
384 MemTransferInst *MemTran = dyn_cast<MemTransferInst>(MI);
385 Value *Src = MemTran ? MemTran->getSource() : 0;
386 Value *Length = MI->getLength();
388 Constant *ConstLength = dyn_cast<Constant>(Length);
389 Instruction *InsertBefore = MI;
391 if (ConstLength->isNullValue()) return false;
393 // The size is not a constant so it could be zero -- check at run-time.
394 IRBuilder<> IRB(InsertBefore);
396 Value *Cmp = IRB.CreateICmpNE(Length,
397 Constant::getNullValue(Length->getType()));
398 InsertBefore = SplitBlockAndInsertIfThen(cast<Instruction>(Cmp), false);
401 instrumentMemIntrinsicParam(MI, Dst, Length, InsertBefore, true);
403 instrumentMemIntrinsicParam(MI, Src, Length, InsertBefore, false);
407 // If I is an interesting memory access, return the PointerOperand
408 // and set IsWrite. Otherwise return NULL.
409 static Value *isInterestingMemoryAccess(Instruction *I, bool *IsWrite) {
410 if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
411 if (!ClInstrumentReads) return NULL;
413 return LI->getPointerOperand();
415 if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
416 if (!ClInstrumentWrites) return NULL;
418 return SI->getPointerOperand();
420 if (AtomicRMWInst *RMW = dyn_cast<AtomicRMWInst>(I)) {
421 if (!ClInstrumentAtomics) return NULL;
423 return RMW->getPointerOperand();
425 if (AtomicCmpXchgInst *XCHG = dyn_cast<AtomicCmpXchgInst>(I)) {
426 if (!ClInstrumentAtomics) return NULL;
428 return XCHG->getPointerOperand();
433 void AddressSanitizer::instrumentMop(Instruction *I) {
434 bool IsWrite = false;
435 Value *Addr = isInterestingMemoryAccess(I, &IsWrite);
437 if (ClOpt && ClOptGlobals) {
438 if (GlobalVariable *G = dyn_cast<GlobalVariable>(Addr)) {
439 // If initialization order checking is disabled, a simple access to a
440 // dynamically initialized global is always valid.
443 // If a global variable does not have dynamic initialization we don't
444 // have to instrument it. However, if a global does not have initailizer
445 // at all, we assume it has dynamic initializer (in other TU).
446 if (G->hasInitializer() && !DynamicallyInitializedGlobals.Contains(G))
451 Type *OrigPtrTy = Addr->getType();
452 Type *OrigTy = cast<PointerType>(OrigPtrTy)->getElementType();
454 assert(OrigTy->isSized());
455 uint32_t TypeSize = TD->getTypeStoreSizeInBits(OrigTy);
457 if (TypeSize != 8 && TypeSize != 16 &&
458 TypeSize != 32 && TypeSize != 64 && TypeSize != 128) {
459 // Ignore all unusual sizes.
464 instrumentAddress(I, IRB, Addr, TypeSize, IsWrite);
467 // Validate the result of Module::getOrInsertFunction called for an interface
468 // function of AddressSanitizer. If the instrumented module defines a function
469 // with the same name, their prototypes must match, otherwise
470 // getOrInsertFunction returns a bitcast.
471 static Function *checkInterfaceFunction(Constant *FuncOrBitcast) {
472 if (isa<Function>(FuncOrBitcast)) return cast<Function>(FuncOrBitcast);
473 FuncOrBitcast->dump();
474 report_fatal_error("trying to redefine an AddressSanitizer "
475 "interface function");
478 Instruction *AddressSanitizer::generateCrashCode(
479 Instruction *InsertBefore, Value *Addr,
480 bool IsWrite, size_t AccessSizeIndex) {
481 IRBuilder<> IRB(InsertBefore);
482 CallInst *Call = IRB.CreateCall(AsanErrorCallback[IsWrite][AccessSizeIndex],
484 // We don't do Call->setDoesNotReturn() because the BB already has
485 // UnreachableInst at the end.
486 // This EmptyAsm is required to avoid callback merge.
487 IRB.CreateCall(EmptyAsm);
491 Value *AddressSanitizer::createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
494 size_t Granularity = 1 << MappingScale();
495 // Addr & (Granularity - 1)
496 Value *LastAccessedByte = IRB.CreateAnd(
497 AddrLong, ConstantInt::get(IntptrTy, Granularity - 1));
498 // (Addr & (Granularity - 1)) + size - 1
499 if (TypeSize / 8 > 1)
500 LastAccessedByte = IRB.CreateAdd(
501 LastAccessedByte, ConstantInt::get(IntptrTy, TypeSize / 8 - 1));
502 // (uint8_t) ((Addr & (Granularity-1)) + size - 1)
503 LastAccessedByte = IRB.CreateIntCast(
504 LastAccessedByte, ShadowValue->getType(), false);
505 // ((uint8_t) ((Addr & (Granularity-1)) + size - 1)) >= ShadowValue
506 return IRB.CreateICmpSGE(LastAccessedByte, ShadowValue);
509 void AddressSanitizer::instrumentAddress(Instruction *OrigIns,
510 IRBuilder<> &IRB, Value *Addr,
511 uint32_t TypeSize, bool IsWrite) {
512 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
514 Type *ShadowTy = IntegerType::get(
515 *C, std::max(8U, TypeSize >> MappingScale()));
516 Type *ShadowPtrTy = PointerType::get(ShadowTy, 0);
517 Value *ShadowPtr = memToShadow(AddrLong, IRB);
518 Value *CmpVal = Constant::getNullValue(ShadowTy);
519 Value *ShadowValue = IRB.CreateLoad(
520 IRB.CreateIntToPtr(ShadowPtr, ShadowPtrTy));
522 Value *Cmp = IRB.CreateICmpNE(ShadowValue, CmpVal);
523 size_t AccessSizeIndex = TypeSizeToSizeIndex(TypeSize);
524 size_t Granularity = 1 << MappingScale();
525 TerminatorInst *CrashTerm = 0;
527 if (ClAlwaysSlowPath || (TypeSize < 8 * Granularity)) {
528 TerminatorInst *CheckTerm =
529 SplitBlockAndInsertIfThen(cast<Instruction>(Cmp), false);
530 assert(dyn_cast<BranchInst>(CheckTerm)->isUnconditional());
531 BasicBlock *NextBB = CheckTerm->getSuccessor(0);
532 IRB.SetInsertPoint(CheckTerm);
533 Value *Cmp2 = createSlowPathCmp(IRB, AddrLong, ShadowValue, TypeSize);
534 BasicBlock *CrashBlock =
535 BasicBlock::Create(*C, "", NextBB->getParent(), NextBB);
536 CrashTerm = new UnreachableInst(*C, CrashBlock);
537 BranchInst *NewTerm = BranchInst::Create(CrashBlock, NextBB, Cmp2);
538 ReplaceInstWithInst(CheckTerm, NewTerm);
540 CrashTerm = SplitBlockAndInsertIfThen(cast<Instruction>(Cmp), true);
544 generateCrashCode(CrashTerm, AddrLong, IsWrite, AccessSizeIndex);
545 Crash->setDebugLoc(OrigIns->getDebugLoc());
548 void AddressSanitizerModule::createInitializerPoisonCalls(
549 Module &M, Value *FirstAddr, Value *LastAddr) {
550 // We do all of our poisoning and unpoisoning within _GLOBAL__I_a.
551 Function *GlobalInit = M.getFunction("_GLOBAL__I_a");
552 // If that function is not present, this TU contains no globals, or they have
553 // all been optimized away
557 // Set up the arguments to our poison/unpoison functions.
558 IRBuilder<> IRB(GlobalInit->begin()->getFirstInsertionPt());
560 // Declare our poisoning and unpoisoning functions.
561 Function *AsanPoisonGlobals = checkInterfaceFunction(M.getOrInsertFunction(
562 kAsanPoisonGlobalsName, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
563 AsanPoisonGlobals->setLinkage(Function::ExternalLinkage);
564 Function *AsanUnpoisonGlobals = checkInterfaceFunction(M.getOrInsertFunction(
565 kAsanUnpoisonGlobalsName, IRB.getVoidTy(), NULL));
566 AsanUnpoisonGlobals->setLinkage(Function::ExternalLinkage);
568 // Add a call to poison all external globals before the given function starts.
569 IRB.CreateCall2(AsanPoisonGlobals, FirstAddr, LastAddr);
571 // Add calls to unpoison all globals before each return instruction.
572 for (Function::iterator I = GlobalInit->begin(), E = GlobalInit->end();
574 if (ReturnInst *RI = dyn_cast<ReturnInst>(I->getTerminator())) {
575 CallInst::Create(AsanUnpoisonGlobals, "", RI);
580 bool AddressSanitizerModule::ShouldInstrumentGlobal(GlobalVariable *G) {
581 Type *Ty = cast<PointerType>(G->getType())->getElementType();
582 DEBUG(dbgs() << "GLOBAL: " << *G << "\n");
584 if (BL->isIn(*G)) return false;
585 if (!Ty->isSized()) return false;
586 if (!G->hasInitializer()) return false;
587 if (GlobalWasGeneratedByAsan(G)) return false; // Our own global.
588 // Touch only those globals that will not be defined in other modules.
589 // Don't handle ODR type linkages since other modules may be built w/o asan.
590 if (G->getLinkage() != GlobalVariable::ExternalLinkage &&
591 G->getLinkage() != GlobalVariable::PrivateLinkage &&
592 G->getLinkage() != GlobalVariable::InternalLinkage)
594 // Two problems with thread-locals:
595 // - The address of the main thread's copy can't be computed at link-time.
596 // - Need to poison all copies, not just the main thread's one.
597 if (G->isThreadLocal())
599 // For now, just ignore this Alloca if the alignment is large.
600 if (G->getAlignment() > RedzoneSize()) return false;
602 // Ignore all the globals with the names starting with "\01L_OBJC_".
603 // Many of those are put into the .cstring section. The linker compresses
604 // that section by removing the spare \0s after the string terminator, so
605 // our redzones get broken.
606 if ((G->getName().find("\01L_OBJC_") == 0) ||
607 (G->getName().find("\01l_OBJC_") == 0)) {
608 DEBUG(dbgs() << "Ignoring \\01L_OBJC_* global: " << *G);
612 if (G->hasSection()) {
613 StringRef Section(G->getSection());
614 // Ignore the globals from the __OBJC section. The ObjC runtime assumes
615 // those conform to /usr/lib/objc/runtime.h, so we can't add redzones to
617 if ((Section.find("__OBJC,") == 0) ||
618 (Section.find("__DATA, __objc_") == 0)) {
619 DEBUG(dbgs() << "Ignoring ObjC runtime global: " << *G);
622 // See http://code.google.com/p/address-sanitizer/issues/detail?id=32
623 // Constant CFString instances are compiled in the following way:
624 // -- the string buffer is emitted into
625 // __TEXT,__cstring,cstring_literals
626 // -- the constant NSConstantString structure referencing that buffer
627 // is placed into __DATA,__cfstring
628 // Therefore there's no point in placing redzones into __DATA,__cfstring.
629 // Moreover, it causes the linker to crash on OS X 10.7
630 if (Section.find("__DATA,__cfstring") == 0) {
631 DEBUG(dbgs() << "Ignoring CFString: " << *G);
639 // This function replaces all global variables with new variables that have
640 // trailing redzones. It also creates a function that poisons
641 // redzones and inserts this function into llvm.global_ctors.
642 bool AddressSanitizerModule::runOnModule(Module &M) {
643 if (!ClGlobals) return false;
644 TD = getAnalysisIfAvailable<DataLayout>();
647 BL.reset(new BlackList(BlacklistFile));
648 if (BL->isIn(M)) return false;
649 DynamicallyInitializedGlobals.Init(M);
650 C = &(M.getContext());
651 IntptrTy = Type::getIntNTy(*C, TD->getPointerSizeInBits());
653 SmallVector<GlobalVariable *, 16> GlobalsToChange;
655 for (Module::GlobalListType::iterator G = M.global_begin(),
656 E = M.global_end(); G != E; ++G) {
657 if (ShouldInstrumentGlobal(G))
658 GlobalsToChange.push_back(G);
661 size_t n = GlobalsToChange.size();
662 if (n == 0) return false;
664 // A global is described by a structure
667 // size_t size_with_redzone;
669 // size_t has_dynamic_init;
670 // We initialize an array of such structures and pass it to a run-time call.
671 StructType *GlobalStructTy = StructType::get(IntptrTy, IntptrTy,
674 SmallVector<Constant *, 16> Initializers(n), DynamicInit;
677 Function *CtorFunc = M.getFunction(kAsanModuleCtorName);
679 IRBuilder<> IRB(CtorFunc->getEntryBlock().getTerminator());
681 // The addresses of the first and last dynamically initialized globals in
682 // this TU. Used in initialization order checking.
683 Value *FirstDynamic = 0, *LastDynamic = 0;
685 for (size_t i = 0; i < n; i++) {
686 GlobalVariable *G = GlobalsToChange[i];
687 PointerType *PtrTy = cast<PointerType>(G->getType());
688 Type *Ty = PtrTy->getElementType();
689 uint64_t SizeInBytes = TD->getTypeAllocSize(Ty);
690 size_t RZ = RedzoneSize();
691 uint64_t RightRedzoneSize = RZ + (RZ - (SizeInBytes % RZ));
692 Type *RightRedZoneTy = ArrayType::get(IRB.getInt8Ty(), RightRedzoneSize);
693 // Determine whether this global should be poisoned in initialization.
694 bool GlobalHasDynamicInitializer =
695 DynamicallyInitializedGlobals.Contains(G);
696 // Don't check initialization order if this global is blacklisted.
697 GlobalHasDynamicInitializer &= !BL->isInInit(*G);
699 StructType *NewTy = StructType::get(Ty, RightRedZoneTy, NULL);
700 Constant *NewInitializer = ConstantStruct::get(
701 NewTy, G->getInitializer(),
702 Constant::getNullValue(RightRedZoneTy), NULL);
704 SmallString<2048> DescriptionOfGlobal = G->getName();
705 DescriptionOfGlobal += " (";
706 DescriptionOfGlobal += M.getModuleIdentifier();
707 DescriptionOfGlobal += ")";
708 GlobalVariable *Name = createPrivateGlobalForString(M, DescriptionOfGlobal);
710 // Create a new global variable with enough space for a redzone.
711 GlobalVariable *NewGlobal = new GlobalVariable(
712 M, NewTy, G->isConstant(), G->getLinkage(),
713 NewInitializer, "", G, G->getThreadLocalMode());
714 NewGlobal->copyAttributesFrom(G);
715 NewGlobal->setAlignment(RZ);
718 Indices2[0] = IRB.getInt32(0);
719 Indices2[1] = IRB.getInt32(0);
721 G->replaceAllUsesWith(
722 ConstantExpr::getGetElementPtr(NewGlobal, Indices2, true));
723 NewGlobal->takeName(G);
724 G->eraseFromParent();
726 Initializers[i] = ConstantStruct::get(
728 ConstantExpr::getPointerCast(NewGlobal, IntptrTy),
729 ConstantInt::get(IntptrTy, SizeInBytes),
730 ConstantInt::get(IntptrTy, SizeInBytes + RightRedzoneSize),
731 ConstantExpr::getPointerCast(Name, IntptrTy),
732 ConstantInt::get(IntptrTy, GlobalHasDynamicInitializer),
735 // Populate the first and last globals declared in this TU.
736 if (CheckInitOrder && GlobalHasDynamicInitializer) {
737 LastDynamic = ConstantExpr::getPointerCast(NewGlobal, IntptrTy);
738 if (FirstDynamic == 0)
739 FirstDynamic = LastDynamic;
742 DEBUG(dbgs() << "NEW GLOBAL: " << *NewGlobal << "\n");
745 ArrayType *ArrayOfGlobalStructTy = ArrayType::get(GlobalStructTy, n);
746 GlobalVariable *AllGlobals = new GlobalVariable(
747 M, ArrayOfGlobalStructTy, false, GlobalVariable::PrivateLinkage,
748 ConstantArray::get(ArrayOfGlobalStructTy, Initializers), "");
750 // Create calls for poisoning before initializers run and unpoisoning after.
751 if (CheckInitOrder && FirstDynamic && LastDynamic)
752 createInitializerPoisonCalls(M, FirstDynamic, LastDynamic);
754 Function *AsanRegisterGlobals = checkInterfaceFunction(M.getOrInsertFunction(
755 kAsanRegisterGlobalsName, IRB.getVoidTy(),
756 IntptrTy, IntptrTy, NULL));
757 AsanRegisterGlobals->setLinkage(Function::ExternalLinkage);
759 IRB.CreateCall2(AsanRegisterGlobals,
760 IRB.CreatePointerCast(AllGlobals, IntptrTy),
761 ConstantInt::get(IntptrTy, n));
763 // We also need to unregister globals at the end, e.g. when a shared library
765 Function *AsanDtorFunction = Function::Create(
766 FunctionType::get(Type::getVoidTy(*C), false),
767 GlobalValue::InternalLinkage, kAsanModuleDtorName, &M);
768 BasicBlock *AsanDtorBB = BasicBlock::Create(*C, "", AsanDtorFunction);
769 IRBuilder<> IRB_Dtor(ReturnInst::Create(*C, AsanDtorBB));
770 Function *AsanUnregisterGlobals =
771 checkInterfaceFunction(M.getOrInsertFunction(
772 kAsanUnregisterGlobalsName,
773 IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
774 AsanUnregisterGlobals->setLinkage(Function::ExternalLinkage);
776 IRB_Dtor.CreateCall2(AsanUnregisterGlobals,
777 IRB.CreatePointerCast(AllGlobals, IntptrTy),
778 ConstantInt::get(IntptrTy, n));
779 appendToGlobalDtors(M, AsanDtorFunction, kAsanCtorAndCtorPriority);
785 void AddressSanitizer::initializeCallbacks(Module &M) {
787 // Create __asan_report* callbacks.
788 for (size_t AccessIsWrite = 0; AccessIsWrite <= 1; AccessIsWrite++) {
789 for (size_t AccessSizeIndex = 0; AccessSizeIndex < kNumberOfAccessSizes;
791 // IsWrite and TypeSize are encoded in the function name.
792 std::string FunctionName = std::string(kAsanReportErrorTemplate) +
793 (AccessIsWrite ? "store" : "load") + itostr(1 << AccessSizeIndex);
794 // If we are merging crash callbacks, they have two parameters.
795 AsanErrorCallback[AccessIsWrite][AccessSizeIndex] =
796 checkInterfaceFunction(M.getOrInsertFunction(
797 FunctionName, IRB.getVoidTy(), IntptrTy, NULL));
801 AsanStackMallocFunc = checkInterfaceFunction(M.getOrInsertFunction(
802 kAsanStackMallocName, IntptrTy, IntptrTy, IntptrTy, NULL));
803 AsanStackFreeFunc = checkInterfaceFunction(M.getOrInsertFunction(
804 kAsanStackFreeName, IRB.getVoidTy(),
805 IntptrTy, IntptrTy, IntptrTy, NULL));
806 AsanHandleNoReturnFunc = checkInterfaceFunction(M.getOrInsertFunction(
807 kAsanHandleNoReturnName, IRB.getVoidTy(), NULL));
808 AsanPoisonStackMemoryFunc = checkInterfaceFunction(M.getOrInsertFunction(
809 kAsanPoisonStackMemoryName, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
810 AsanUnpoisonStackMemoryFunc = checkInterfaceFunction(M.getOrInsertFunction(
811 kAsanUnpoisonStackMemoryName, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
813 // We insert an empty inline asm after __asan_report* to avoid callback merge.
814 EmptyAsm = InlineAsm::get(FunctionType::get(IRB.getVoidTy(), false),
815 StringRef(""), StringRef(""),
816 /*hasSideEffects=*/true);
820 bool AddressSanitizer::doInitialization(Module &M) {
821 // Initialize the private fields. No one has accessed them before.
822 TD = getAnalysisIfAvailable<DataLayout>();
826 BL.reset(new BlackList(BlacklistFile));
827 DynamicallyInitializedGlobals.Init(M);
829 C = &(M.getContext());
830 LongSize = TD->getPointerSizeInBits();
831 IntptrTy = Type::getIntNTy(*C, LongSize);
832 IntptrPtrTy = PointerType::get(IntptrTy, 0);
834 AsanCtorFunction = Function::Create(
835 FunctionType::get(Type::getVoidTy(*C), false),
836 GlobalValue::InternalLinkage, kAsanModuleCtorName, &M);
837 BasicBlock *AsanCtorBB = BasicBlock::Create(*C, "", AsanCtorFunction);
838 // call __asan_init in the module ctor.
839 IRBuilder<> IRB(ReturnInst::Create(*C, AsanCtorBB));
840 AsanInitFunction = checkInterfaceFunction(
841 M.getOrInsertFunction(kAsanInitName, IRB.getVoidTy(), NULL));
842 AsanInitFunction->setLinkage(Function::ExternalLinkage);
843 IRB.CreateCall(AsanInitFunction);
845 llvm::Triple targetTriple(M.getTargetTriple());
846 bool isAndroid = targetTriple.getEnvironment() == llvm::Triple::Android;
848 MappingOffset = isAndroid ? kDefaultShadowOffsetAndroid :
849 (LongSize == 32 ? kDefaultShadowOffset32 : kDefaultShadowOffset64);
850 if (ClMappingOffsetLog >= 0) {
851 if (ClMappingOffsetLog == 0) {
855 MappingOffset = 1ULL << ClMappingOffsetLog;
860 if (ClMappingOffsetLog >= 0) {
861 // Tell the run-time the current values of mapping offset and scale.
862 GlobalValue *asan_mapping_offset =
863 new GlobalVariable(M, IntptrTy, true, GlobalValue::LinkOnceODRLinkage,
864 ConstantInt::get(IntptrTy, MappingOffset),
865 kAsanMappingOffsetName);
866 // Read the global, otherwise it may be optimized away.
867 IRB.CreateLoad(asan_mapping_offset, true);
869 if (ClMappingScale) {
870 GlobalValue *asan_mapping_scale =
871 new GlobalVariable(M, IntptrTy, true, GlobalValue::LinkOnceODRLinkage,
872 ConstantInt::get(IntptrTy, MappingScale()),
873 kAsanMappingScaleName);
874 // Read the global, otherwise it may be optimized away.
875 IRB.CreateLoad(asan_mapping_scale, true);
878 appendToGlobalCtors(M, AsanCtorFunction, kAsanCtorAndCtorPriority);
883 bool AddressSanitizer::maybeInsertAsanInitAtFunctionEntry(Function &F) {
884 // For each NSObject descendant having a +load method, this method is invoked
885 // by the ObjC runtime before any of the static constructors is called.
886 // Therefore we need to instrument such methods with a call to __asan_init
887 // at the beginning in order to initialize our runtime before any access to
888 // the shadow memory.
889 // We cannot just ignore these methods, because they may call other
890 // instrumented functions.
891 if (F.getName().find(" load]") != std::string::npos) {
892 IRBuilder<> IRB(F.begin()->begin());
893 IRB.CreateCall(AsanInitFunction);
899 bool AddressSanitizer::runOnFunction(Function &F) {
900 if (BL->isIn(F)) return false;
901 if (&F == AsanCtorFunction) return false;
902 DEBUG(dbgs() << "ASAN instrumenting:\n" << F << "\n");
903 initializeCallbacks(*F.getParent());
905 // If needed, insert __asan_init before checking for AddressSafety attr.
906 maybeInsertAsanInitAtFunctionEntry(F);
908 if (!F.getFnAttributes().hasAttribute(Attributes::AddressSafety))
911 if (!ClDebugFunc.empty() && ClDebugFunc != F.getName())
914 // We want to instrument every address only once per basic block (unless there
915 // are calls between uses).
916 SmallSet<Value*, 16> TempsToInstrument;
917 SmallVector<Instruction*, 16> ToInstrument;
918 SmallVector<Instruction*, 8> NoReturnCalls;
921 // Fill the set of memory operations to instrument.
922 for (Function::iterator FI = F.begin(), FE = F.end();
924 TempsToInstrument.clear();
925 int NumInsnsPerBB = 0;
926 for (BasicBlock::iterator BI = FI->begin(), BE = FI->end();
928 if (LooksLikeCodeInBug11395(BI)) return false;
929 if (Value *Addr = isInterestingMemoryAccess(BI, &IsWrite)) {
930 if (ClOpt && ClOptSameTemp) {
931 if (!TempsToInstrument.insert(Addr))
932 continue; // We've seen this temp in the current BB.
934 } else if (isa<MemIntrinsic>(BI) && ClMemIntrin) {
937 if (CallInst *CI = dyn_cast<CallInst>(BI)) {
939 TempsToInstrument.clear();
940 if (CI->doesNotReturn()) {
941 NoReturnCalls.push_back(CI);
946 ToInstrument.push_back(BI);
948 if (NumInsnsPerBB >= ClMaxInsnsToInstrumentPerBB)
954 int NumInstrumented = 0;
955 for (size_t i = 0, n = ToInstrument.size(); i != n; i++) {
956 Instruction *Inst = ToInstrument[i];
957 if (ClDebugMin < 0 || ClDebugMax < 0 ||
958 (NumInstrumented >= ClDebugMin && NumInstrumented <= ClDebugMax)) {
959 if (isInterestingMemoryAccess(Inst, &IsWrite))
962 instrumentMemIntrinsic(cast<MemIntrinsic>(Inst));
967 bool ChangedStack = poisonStackInFunction(F);
969 // We must unpoison the stack before every NoReturn call (throw, _exit, etc).
970 // See e.g. http://code.google.com/p/address-sanitizer/issues/detail?id=37
971 for (size_t i = 0, n = NoReturnCalls.size(); i != n; i++) {
972 Instruction *CI = NoReturnCalls[i];
974 IRB.CreateCall(AsanHandleNoReturnFunc);
976 DEBUG(dbgs() << "ASAN done instrumenting:\n" << F << "\n");
978 return NumInstrumented > 0 || ChangedStack || !NoReturnCalls.empty();
981 static uint64_t ValueForPoison(uint64_t PoisonByte, size_t ShadowRedzoneSize) {
982 if (ShadowRedzoneSize == 1) return PoisonByte;
983 if (ShadowRedzoneSize == 2) return (PoisonByte << 8) + PoisonByte;
984 if (ShadowRedzoneSize == 4)
985 return (PoisonByte << 24) + (PoisonByte << 16) +
986 (PoisonByte << 8) + (PoisonByte);
987 llvm_unreachable("ShadowRedzoneSize is either 1, 2 or 4");
990 static void PoisonShadowPartialRightRedzone(uint8_t *Shadow,
993 size_t ShadowGranularity,
995 for (size_t i = 0; i < RZSize;
996 i+= ShadowGranularity, Shadow++) {
997 if (i + ShadowGranularity <= Size) {
998 *Shadow = 0; // fully addressable
999 } else if (i >= Size) {
1000 *Shadow = Magic; // unaddressable
1002 *Shadow = Size - i; // first Size-i bytes are addressable
1007 void AddressSanitizer::PoisonStack(const ArrayRef<AllocaInst*> &AllocaVec,
1009 Value *ShadowBase, bool DoPoison) {
1010 size_t ShadowRZSize = RedzoneSize() >> MappingScale();
1011 assert(ShadowRZSize >= 1 && ShadowRZSize <= 4);
1012 Type *RZTy = Type::getIntNTy(*C, ShadowRZSize * 8);
1013 Type *RZPtrTy = PointerType::get(RZTy, 0);
1015 Value *PoisonLeft = ConstantInt::get(RZTy,
1016 ValueForPoison(DoPoison ? kAsanStackLeftRedzoneMagic : 0LL, ShadowRZSize));
1017 Value *PoisonMid = ConstantInt::get(RZTy,
1018 ValueForPoison(DoPoison ? kAsanStackMidRedzoneMagic : 0LL, ShadowRZSize));
1019 Value *PoisonRight = ConstantInt::get(RZTy,
1020 ValueForPoison(DoPoison ? kAsanStackRightRedzoneMagic : 0LL, ShadowRZSize));
1022 // poison the first red zone.
1023 IRB.CreateStore(PoisonLeft, IRB.CreateIntToPtr(ShadowBase, RZPtrTy));
1025 // poison all other red zones.
1026 uint64_t Pos = RedzoneSize();
1027 for (size_t i = 0, n = AllocaVec.size(); i < n; i++) {
1028 AllocaInst *AI = AllocaVec[i];
1029 uint64_t SizeInBytes = getAllocaSizeInBytes(AI);
1030 uint64_t AlignedSize = getAlignedAllocaSize(AI);
1031 assert(AlignedSize - SizeInBytes < RedzoneSize());
1036 assert(ShadowBase->getType() == IntptrTy);
1037 if (SizeInBytes < AlignedSize) {
1038 // Poison the partial redzone at right
1039 Ptr = IRB.CreateAdd(
1040 ShadowBase, ConstantInt::get(IntptrTy,
1041 (Pos >> MappingScale()) - ShadowRZSize));
1042 size_t AddressableBytes = RedzoneSize() - (AlignedSize - SizeInBytes);
1043 uint32_t Poison = 0;
1045 PoisonShadowPartialRightRedzone((uint8_t*)&Poison, AddressableBytes,
1047 1ULL << MappingScale(),
1048 kAsanStackPartialRedzoneMagic);
1050 Value *PartialPoison = ConstantInt::get(RZTy, Poison);
1051 IRB.CreateStore(PartialPoison, IRB.CreateIntToPtr(Ptr, RZPtrTy));
1054 // Poison the full redzone at right.
1055 Ptr = IRB.CreateAdd(ShadowBase,
1056 ConstantInt::get(IntptrTy, Pos >> MappingScale()));
1057 Value *Poison = i == AllocaVec.size() - 1 ? PoisonRight : PoisonMid;
1058 IRB.CreateStore(Poison, IRB.CreateIntToPtr(Ptr, RZPtrTy));
1060 Pos += RedzoneSize();
1064 // Workaround for bug 11395: we don't want to instrument stack in functions
1065 // with large assembly blobs (32-bit only), otherwise reg alloc may crash.
1066 // FIXME: remove once the bug 11395 is fixed.
1067 bool AddressSanitizer::LooksLikeCodeInBug11395(Instruction *I) {
1068 if (LongSize != 32) return false;
1069 CallInst *CI = dyn_cast<CallInst>(I);
1070 if (!CI || !CI->isInlineAsm()) return false;
1071 if (CI->getNumArgOperands() <= 5) return false;
1072 // We have inline assembly with quite a few arguments.
1076 // Handling llvm.lifetime intrinsics for a given %alloca:
1077 // (1) collect all llvm.lifetime.xxx(%size, %value) describing the alloca.
1078 // (2) if %size is constant, poison memory for llvm.lifetime.end (to detect
1079 // invalid accesses) and unpoison it for llvm.lifetime.start (the memory
1080 // could be poisoned by previous llvm.lifetime.end instruction, as the
1081 // variable may go in and out of scope several times, e.g. in loops).
1082 // (3) if we poisoned at least one %alloca in a function,
1083 // unpoison the whole stack frame at function exit.
1084 bool AddressSanitizer::handleAllocaLifetime(Value *Alloca) {
1085 assert(CheckLifetime);
1086 Type *AllocaType = Alloca->getType();
1087 Type *Int8PtrTy = Type::getInt8PtrTy(AllocaType->getContext());
1090 // Typical code looks like this:
1091 // %alloca = alloca <type>, <alignment>
1092 // ... some code ...
1093 // %val1 = bitcast <type>* %alloca to i8*
1094 // call void @llvm.lifetime.start(i64 <size>, i8* %val1)
1095 // ... more code ...
1096 // %val2 = bitcast <type>* %alloca to i8*
1097 // call void @llvm.lifetime.start(i64 <size>, i8* %val2)
1098 // That is, to handle %alloca we must find all its casts to
1099 // i8* values, and find lifetime instructions for these values.
1100 if (AllocaType == Int8PtrTy)
1101 Res |= handleValueLifetime(Alloca);
1102 for (Value::use_iterator UI = Alloca->use_begin(), UE = Alloca->use_end();
1104 if (UI->getType() != Int8PtrTy) continue;
1105 if (UI->stripPointerCasts() != Alloca) continue;
1106 Res |= handleValueLifetime(*UI);
1111 bool AddressSanitizer::handleValueLifetime(Value *V) {
1112 assert(CheckLifetime);
1114 for (Value::use_iterator UI = V->use_begin(), UE = V->use_end(); UI != UE;
1116 IntrinsicInst *II = dyn_cast<IntrinsicInst>(*UI);
1118 Intrinsic::ID ID = II->getIntrinsicID();
1119 if (ID != Intrinsic::lifetime_start &&
1120 ID != Intrinsic::lifetime_end)
1122 if (V != II->getArgOperand(1))
1124 // Found lifetime intrinsic, add ASan instrumentation if necessary.
1125 ConstantInt *Size = dyn_cast<ConstantInt>(II->getArgOperand(0));
1126 // If size argument is undefined, don't do anything.
1127 if (Size->isMinusOne())
1129 // Check that size doesn't saturate uint64_t and can
1130 // be stored in IntptrTy.
1131 const uint64_t SizeValue = Size->getValue().getLimitedValue();
1132 if (SizeValue == ~0ULL ||
1133 !ConstantInt::isValueValidForType(IntptrTy, SizeValue)) {
1136 IRBuilder<> IRB(II);
1137 bool DoPoison = (ID == Intrinsic::lifetime_end);
1138 poisonAlloca(V, SizeValue, IRB, DoPoison);
1144 // Find all static Alloca instructions and put
1145 // poisoned red zones around all of them.
1146 // Then unpoison everything back before the function returns.
1148 // Stack poisoning does not play well with exception handling.
1149 // When an exception is thrown, we essentially bypass the code
1150 // that unpoisones the stack. This is why the run-time library has
1151 // to intercept __cxa_throw (as well as longjmp, etc) and unpoison the entire
1152 // stack in the interceptor. This however does not work inside the
1153 // actual function which catches the exception. Most likely because the
1154 // compiler hoists the load of the shadow value somewhere too high.
1155 // This causes asan to report a non-existing bug on 453.povray.
1156 // It sounds like an LLVM bug.
1157 bool AddressSanitizer::poisonStackInFunction(Function &F) {
1158 if (!ClStack) return false;
1159 SmallVector<AllocaInst*, 16> AllocaVec;
1160 SmallVector<Instruction*, 8> RetVec;
1161 uint64_t TotalSize = 0;
1162 bool HavePoisonedAllocas = false;
1163 DIBuilder DIB(*F.getParent());
1165 // Filter out Alloca instructions we want (and can) handle.
1166 // Collect Ret instructions.
1167 unsigned ResultAlignment = 1 << MappingScale();
1168 for (Function::iterator FI = F.begin(), FE = F.end();
1170 BasicBlock &BB = *FI;
1171 for (BasicBlock::iterator BI = BB.begin(), BE = BB.end();
1173 if (isa<ReturnInst>(BI)) {
1174 RetVec.push_back(BI);
1178 AllocaInst *AI = dyn_cast<AllocaInst>(BI);
1180 if (AI->isArrayAllocation()) continue;
1181 if (!AI->isStaticAlloca()) continue;
1182 if (!AI->getAllocatedType()->isSized()) continue;
1183 ResultAlignment = std::max(ResultAlignment, AI->getAlignment());
1184 AllocaVec.push_back(AI);
1185 uint64_t AlignedSize = getAlignedAllocaSize(AI);
1186 TotalSize += AlignedSize;
1190 if (AllocaVec.empty()) return false;
1192 uint64_t LocalStackSize = TotalSize + (AllocaVec.size() + 1) * RedzoneSize();
1194 bool DoStackMalloc = CheckUseAfterReturn
1195 && LocalStackSize <= kMaxStackMallocSize;
1197 Instruction *InsBefore = AllocaVec[0];
1198 IRBuilder<> IRB(InsBefore);
1201 Type *ByteArrayTy = ArrayType::get(IRB.getInt8Ty(), LocalStackSize);
1202 AllocaInst *MyAlloca =
1203 new AllocaInst(ByteArrayTy, "MyAlloca", InsBefore);
1204 if (ClRealignStack && ResultAlignment < RedzoneSize())
1205 ResultAlignment = RedzoneSize();
1206 MyAlloca->setAlignment(ResultAlignment);
1207 assert(MyAlloca->isStaticAlloca());
1208 Value *OrigStackBase = IRB.CreatePointerCast(MyAlloca, IntptrTy);
1209 Value *LocalStackBase = OrigStackBase;
1211 if (DoStackMalloc) {
1212 LocalStackBase = IRB.CreateCall2(AsanStackMallocFunc,
1213 ConstantInt::get(IntptrTy, LocalStackSize), OrigStackBase);
1216 // This string will be parsed by the run-time (DescribeStackAddress).
1217 SmallString<2048> StackDescriptionStorage;
1218 raw_svector_ostream StackDescription(StackDescriptionStorage);
1219 StackDescription << F.getName() << " " << AllocaVec.size() << " ";
1221 uint64_t Pos = RedzoneSize();
1222 // Replace Alloca instructions with base+offset.
1223 for (size_t i = 0, n = AllocaVec.size(); i < n; i++) {
1224 AllocaInst *AI = AllocaVec[i];
1225 uint64_t SizeInBytes = getAllocaSizeInBytes(AI);
1226 StringRef Name = AI->getName();
1227 StackDescription << Pos << " " << SizeInBytes << " "
1228 << Name.size() << " " << Name << " ";
1229 uint64_t AlignedSize = getAlignedAllocaSize(AI);
1230 assert((AlignedSize % RedzoneSize()) == 0);
1231 Value *NewAllocaPtr = IRB.CreateIntToPtr(
1232 IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy, Pos)),
1234 replaceDbgDeclareForAlloca(AI, NewAllocaPtr, DIB);
1235 AI->replaceAllUsesWith(NewAllocaPtr);
1236 // Analyze lifetime intrinsics only for static allocas we handle.
1238 HavePoisonedAllocas |= handleAllocaLifetime(NewAllocaPtr);
1239 Pos += AlignedSize + RedzoneSize();
1241 assert(Pos == LocalStackSize);
1243 // Write the Magic value and the frame description constant to the redzone.
1244 Value *BasePlus0 = IRB.CreateIntToPtr(LocalStackBase, IntptrPtrTy);
1245 IRB.CreateStore(ConstantInt::get(IntptrTy, kCurrentStackFrameMagic),
1247 Value *BasePlus1 = IRB.CreateAdd(LocalStackBase,
1248 ConstantInt::get(IntptrTy, LongSize/8));
1249 BasePlus1 = IRB.CreateIntToPtr(BasePlus1, IntptrPtrTy);
1250 GlobalVariable *StackDescriptionGlobal =
1251 createPrivateGlobalForString(*F.getParent(), StackDescription.str());
1252 Value *Description = IRB.CreatePointerCast(StackDescriptionGlobal, IntptrTy);
1253 IRB.CreateStore(Description, BasePlus1);
1255 // Poison the stack redzones at the entry.
1256 Value *ShadowBase = memToShadow(LocalStackBase, IRB);
1257 PoisonStack(ArrayRef<AllocaInst*>(AllocaVec), IRB, ShadowBase, true);
1259 // Unpoison the stack before all ret instructions.
1260 for (size_t i = 0, n = RetVec.size(); i < n; i++) {
1261 Instruction *Ret = RetVec[i];
1262 IRBuilder<> IRBRet(Ret);
1264 // Mark the current frame as retired.
1265 IRBRet.CreateStore(ConstantInt::get(IntptrTy, kRetiredStackFrameMagic),
1267 // Unpoison the stack.
1268 PoisonStack(ArrayRef<AllocaInst*>(AllocaVec), IRBRet, ShadowBase, false);
1270 if (DoStackMalloc) {
1271 // In use-after-return mode, mark the whole stack frame unaddressable.
1272 IRBRet.CreateCall3(AsanStackFreeFunc, LocalStackBase,
1273 ConstantInt::get(IntptrTy, LocalStackSize),
1275 } else if (HavePoisonedAllocas) {
1276 // If we poisoned some allocas in llvm.lifetime analysis,
1277 // unpoison whole stack frame now.
1278 assert(LocalStackBase == OrigStackBase);
1279 poisonAlloca(LocalStackBase, LocalStackSize, IRBRet, false);
1283 // We are done. Remove the old unused alloca instructions.
1284 for (size_t i = 0, n = AllocaVec.size(); i < n; i++)
1285 AllocaVec[i]->eraseFromParent();
1294 void AddressSanitizer::poisonAlloca(Value *V, uint64_t Size, IRBuilder<> IRB,
1296 // For now just insert the call to ASan runtime.
1297 Value *AddrArg = IRB.CreatePointerCast(V, IntptrTy);
1298 Value *SizeArg = ConstantInt::get(IntptrTy, Size);
1299 IRB.CreateCall2(DoPoison ? AsanPoisonStackMemoryFunc
1300 : AsanUnpoisonStackMemoryFunc,