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/Function.h"
29 #include "llvm/IRBuilder.h"
30 #include "llvm/InlineAsm.h"
31 #include "llvm/IntrinsicInst.h"
32 #include "llvm/LLVMContext.h"
33 #include "llvm/Module.h"
34 #include "llvm/Support/CommandLine.h"
35 #include "llvm/Support/DataTypes.h"
36 #include "llvm/Support/Debug.h"
37 #include "llvm/Support/raw_ostream.h"
38 #include "llvm/Support/system_error.h"
39 #include "llvm/Target/TargetMachine.h"
40 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
41 #include "llvm/Transforms/Utils/ModuleUtils.h"
42 #include "llvm/Type.h"
48 static const uint64_t kDefaultShadowScale = 3;
49 static const uint64_t kDefaultShadowOffset32 = 1ULL << 29;
50 static const uint64_t kDefaultShadowOffset64 = 1ULL << 44;
51 static const uint64_t kDefaultShadowOffsetAndroid = 0;
53 static const size_t kMaxStackMallocSize = 1 << 16; // 64K
54 static const uintptr_t kCurrentStackFrameMagic = 0x41B58AB3;
55 static const uintptr_t kRetiredStackFrameMagic = 0x45E0360E;
57 static const char *kAsanModuleCtorName = "asan.module_ctor";
58 static const char *kAsanModuleDtorName = "asan.module_dtor";
59 static const int kAsanCtorAndCtorPriority = 1;
60 static const char *kAsanReportErrorTemplate = "__asan_report_";
61 static const char *kAsanRegisterGlobalsName = "__asan_register_globals";
62 static const char *kAsanUnregisterGlobalsName = "__asan_unregister_globals";
63 static const char *kAsanPoisonGlobalsName = "__asan_before_dynamic_init";
64 static const char *kAsanUnpoisonGlobalsName = "__asan_after_dynamic_init";
65 static const char *kAsanInitName = "__asan_init";
66 static const char *kAsanHandleNoReturnName = "__asan_handle_no_return";
67 static const char *kAsanMappingOffsetName = "__asan_mapping_offset";
68 static const char *kAsanMappingScaleName = "__asan_mapping_scale";
69 static const char *kAsanStackMallocName = "__asan_stack_malloc";
70 static const char *kAsanStackFreeName = "__asan_stack_free";
71 static const char *kAsanGenPrefix = "__asan_gen_";
72 static const char *kAsanPoisonStackMemoryName = "__asan_poison_stack_memory";
73 static const char *kAsanUnpoisonStackMemoryName =
74 "__asan_unpoison_stack_memory";
76 static const int kAsanStackLeftRedzoneMagic = 0xf1;
77 static const int kAsanStackMidRedzoneMagic = 0xf2;
78 static const int kAsanStackRightRedzoneMagic = 0xf3;
79 static const int kAsanStackPartialRedzoneMagic = 0xf4;
81 // Accesses sizes are powers of two: 1, 2, 4, 8, 16.
82 static const size_t kNumberOfAccessSizes = 5;
84 // Command-line flags.
86 // This flag may need to be replaced with -f[no-]asan-reads.
87 static cl::opt<bool> ClInstrumentReads("asan-instrument-reads",
88 cl::desc("instrument read instructions"), cl::Hidden, cl::init(true));
89 static cl::opt<bool> ClInstrumentWrites("asan-instrument-writes",
90 cl::desc("instrument write instructions"), cl::Hidden, cl::init(true));
91 static cl::opt<bool> ClInstrumentAtomics("asan-instrument-atomics",
92 cl::desc("instrument atomic instructions (rmw, cmpxchg)"),
93 cl::Hidden, cl::init(true));
94 static cl::opt<bool> ClAlwaysSlowPath("asan-always-slow-path",
95 cl::desc("use instrumentation with slow path for all accesses"),
96 cl::Hidden, cl::init(false));
97 // This flag limits the number of instructions to be instrumented
98 // in any given BB. Normally, this should be set to unlimited (INT_MAX),
99 // but due to http://llvm.org/bugs/show_bug.cgi?id=12652 we temporary
101 static cl::opt<int> ClMaxInsnsToInstrumentPerBB("asan-max-ins-per-bb",
103 cl::desc("maximal number of instructions to instrument in any given BB"),
105 // This flag may need to be replaced with -f[no]asan-stack.
106 static cl::opt<bool> ClStack("asan-stack",
107 cl::desc("Handle stack memory"), cl::Hidden, cl::init(true));
108 // This flag may need to be replaced with -f[no]asan-use-after-return.
109 static cl::opt<bool> ClUseAfterReturn("asan-use-after-return",
110 cl::desc("Check return-after-free"), cl::Hidden, cl::init(false));
111 // This flag may need to be replaced with -f[no]asan-globals.
112 static cl::opt<bool> ClGlobals("asan-globals",
113 cl::desc("Handle global objects"), cl::Hidden, cl::init(true));
114 static cl::opt<bool> ClInitializers("asan-initialization-order",
115 cl::desc("Handle C++ initializer order"), cl::Hidden, cl::init(false));
116 static cl::opt<bool> ClMemIntrin("asan-memintrin",
117 cl::desc("Handle memset/memcpy/memmove"), cl::Hidden, cl::init(true));
118 static cl::opt<std::string> ClBlacklistFile("asan-blacklist",
119 cl::desc("File containing the list of objects to ignore "
120 "during instrumentation"), cl::Hidden);
122 // These flags allow to change the shadow mapping.
123 // The shadow mapping looks like
124 // Shadow = (Mem >> scale) + (1 << offset_log)
125 static cl::opt<int> ClMappingScale("asan-mapping-scale",
126 cl::desc("scale of asan shadow mapping"), cl::Hidden, cl::init(0));
127 static cl::opt<int> ClMappingOffsetLog("asan-mapping-offset-log",
128 cl::desc("offset of asan shadow mapping"), cl::Hidden, cl::init(-1));
130 // Optimization flags. Not user visible, used mostly for testing
131 // and benchmarking the tool.
132 static cl::opt<bool> ClOpt("asan-opt",
133 cl::desc("Optimize instrumentation"), cl::Hidden, cl::init(true));
134 static cl::opt<bool> ClOptSameTemp("asan-opt-same-temp",
135 cl::desc("Instrument the same temp just once"), cl::Hidden,
137 static cl::opt<bool> ClOptGlobals("asan-opt-globals",
138 cl::desc("Don't instrument scalar globals"), cl::Hidden, cl::init(true));
140 static cl::opt<bool> ClCheckLifetime("asan-check-lifetime",
141 cl::desc("Use llvm.lifetime intrinsics to insert extra checks"),
142 cl::Hidden, cl::init(false));
145 static cl::opt<int> ClDebug("asan-debug", cl::desc("debug"), cl::Hidden,
147 static cl::opt<int> ClDebugStack("asan-debug-stack", cl::desc("debug stack"),
148 cl::Hidden, cl::init(0));
149 static cl::opt<std::string> ClDebugFunc("asan-debug-func",
150 cl::Hidden, cl::desc("Debug func"));
151 static cl::opt<int> ClDebugMin("asan-debug-min", cl::desc("Debug min inst"),
152 cl::Hidden, cl::init(-1));
153 static cl::opt<int> ClDebugMax("asan-debug-max", cl::desc("Debug man inst"),
154 cl::Hidden, cl::init(-1));
157 /// A set of dynamically initialized globals extracted from metadata.
158 class SetOfDynamicallyInitializedGlobals {
160 void Init(Module& M) {
161 // Clang generates metadata identifying all dynamically initialized globals.
162 NamedMDNode *DynamicGlobals =
163 M.getNamedMetadata("llvm.asan.dynamically_initialized_globals");
166 for (int i = 0, n = DynamicGlobals->getNumOperands(); i < n; ++i) {
167 MDNode *MDN = DynamicGlobals->getOperand(i);
168 assert(MDN->getNumOperands() == 1);
169 Value *VG = MDN->getOperand(0);
170 // The optimizer may optimize away a global entirely, in which case we
171 // cannot instrument access to it.
174 DynInitGlobals.insert(cast<GlobalVariable>(VG));
177 bool Contains(GlobalVariable *G) { return DynInitGlobals.count(G) != 0; }
179 SmallSet<GlobalValue*, 32> DynInitGlobals;
182 static int MappingScale() {
183 return ClMappingScale ? ClMappingScale : kDefaultShadowScale;
186 static size_t RedzoneSize() {
187 // Redzone used for stack and globals is at least 32 bytes.
188 // For scales 6 and 7, the redzone has to be 64 and 128 bytes respectively.
189 return std::max(32U, 1U << MappingScale());
192 /// AddressSanitizer: instrument the code in module to find memory bugs.
193 struct AddressSanitizer : public FunctionPass {
194 AddressSanitizer(bool CheckInitOrder = false,
195 bool CheckUseAfterReturn = false,
196 bool CheckLifetime = false,
197 StringRef BlacklistFile = StringRef())
199 CheckInitOrder(CheckInitOrder || ClInitializers),
200 CheckUseAfterReturn(CheckUseAfterReturn || ClUseAfterReturn),
201 CheckLifetime(CheckLifetime || ClCheckLifetime),
202 BlacklistFile(BlacklistFile.empty() ? ClBlacklistFile
204 virtual const char *getPassName() const {
205 return "AddressSanitizerFunctionPass";
207 void instrumentMop(Instruction *I);
208 void instrumentAddress(Instruction *OrigIns, IRBuilder<> &IRB,
209 Value *Addr, uint32_t TypeSize, bool IsWrite);
210 Value *createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
211 Value *ShadowValue, uint32_t TypeSize);
212 Instruction *generateCrashCode(Instruction *InsertBefore, Value *Addr,
213 bool IsWrite, size_t AccessSizeIndex);
214 bool instrumentMemIntrinsic(MemIntrinsic *MI);
215 void instrumentMemIntrinsicParam(Instruction *OrigIns, Value *Addr,
217 Instruction *InsertBefore, bool IsWrite);
218 Value *memToShadow(Value *Shadow, IRBuilder<> &IRB);
219 bool runOnFunction(Function &F);
220 void createInitializerPoisonCalls(Module &M,
221 Value *FirstAddr, Value *LastAddr);
222 bool maybeInsertAsanInitAtFunctionEntry(Function &F);
223 bool poisonStackInFunction(Function &F);
224 virtual bool doInitialization(Module &M);
225 static char ID; // Pass identification, replacement for typeid
228 void initializeCallbacks(Module &M);
229 uint64_t getAllocaSizeInBytes(AllocaInst *AI) {
230 Type *Ty = AI->getAllocatedType();
231 uint64_t SizeInBytes = TD->getTypeAllocSize(Ty);
234 uint64_t getAlignedSize(uint64_t SizeInBytes) {
235 size_t RZ = RedzoneSize();
236 return ((SizeInBytes + RZ - 1) / RZ) * RZ;
238 uint64_t getAlignedAllocaSize(AllocaInst *AI) {
239 uint64_t SizeInBytes = getAllocaSizeInBytes(AI);
240 return getAlignedSize(SizeInBytes);
243 bool ShouldInstrumentGlobal(GlobalVariable *G);
244 void PoisonStack(const ArrayRef<AllocaInst*> &AllocaVec, IRBuilder<> IRB,
245 Value *ShadowBase, bool DoPoison);
246 bool LooksLikeCodeInBug11395(Instruction *I);
247 void FindDynamicInitializers(Module &M);
248 /// Analyze lifetime intrinsics for given alloca. Use Value* instead of
249 /// AllocaInst* here, as we call this method after we merge all allocas into a
250 /// single one. Returns true if ASan added some instrumentation.
251 bool handleAllocaLifetime(Value *Alloca);
252 /// Analyze lifetime intrinsics for a specific value, casted from alloca.
253 /// Returns true if if ASan added some instrumentation.
254 bool handleValueLifetime(Value *V);
255 void poisonAlloca(Value *V, uint64_t Size, IRBuilder<> IRB, bool DoPoison);
258 bool CheckUseAfterReturn;
262 uint64_t MappingOffset;
266 Function *AsanCtorFunction;
267 Function *AsanInitFunction;
268 Function *AsanStackMallocFunc, *AsanStackFreeFunc;
269 Function *AsanPoisonStackMemoryFunc, *AsanUnpoisonStackMemoryFunc;
270 Function *AsanHandleNoReturnFunc;
271 SmallString<64> BlacklistFile;
272 OwningPtr<BlackList> BL;
273 // This array is indexed by AccessIsWrite and log2(AccessSize).
274 Function *AsanErrorCallback[2][kNumberOfAccessSizes];
276 SetOfDynamicallyInitializedGlobals DynamicallyInitializedGlobals;
279 class AddressSanitizerModule : public ModulePass {
281 AddressSanitizerModule(bool CheckInitOrder = false,
282 StringRef BlacklistFile = StringRef())
284 CheckInitOrder(CheckInitOrder || ClInitializers),
285 BlacklistFile(BlacklistFile.empty() ? ClBlacklistFile
287 bool runOnModule(Module &M);
288 static char ID; // Pass identification, replacement for typeid
289 virtual const char *getPassName() const {
290 return "AddressSanitizerModule";
294 bool ShouldInstrumentGlobal(GlobalVariable *G);
295 void createInitializerPoisonCalls(Module &M, Value *FirstAddr,
299 SmallString<64> BlacklistFile;
300 OwningPtr<BlackList> BL;
301 SetOfDynamicallyInitializedGlobals DynamicallyInitializedGlobals;
309 char AddressSanitizer::ID = 0;
310 INITIALIZE_PASS(AddressSanitizer, "asan",
311 "AddressSanitizer: detects use-after-free and out-of-bounds bugs.",
313 FunctionPass *llvm::createAddressSanitizerFunctionPass(
314 bool CheckInitOrder, bool CheckUseAfterReturn, bool CheckLifetime,
315 StringRef BlacklistFile) {
316 return new AddressSanitizer(CheckInitOrder, CheckUseAfterReturn,
317 CheckLifetime, BlacklistFile);
320 char AddressSanitizerModule::ID = 0;
321 INITIALIZE_PASS(AddressSanitizerModule, "asan-module",
322 "AddressSanitizer: detects use-after-free and out-of-bounds bugs."
323 "ModulePass", false, false)
324 ModulePass *llvm::createAddressSanitizerModulePass(
325 bool CheckInitOrder, StringRef BlacklistFile) {
326 return new AddressSanitizerModule(CheckInitOrder, BlacklistFile);
329 static size_t TypeSizeToSizeIndex(uint32_t TypeSize) {
330 size_t Res = CountTrailingZeros_32(TypeSize / 8);
331 assert(Res < kNumberOfAccessSizes);
335 // Create a constant for Str so that we can pass it to the run-time lib.
336 static GlobalVariable *createPrivateGlobalForString(Module &M, StringRef Str) {
337 Constant *StrConst = ConstantDataArray::getString(M.getContext(), Str);
338 return new GlobalVariable(M, StrConst->getType(), true,
339 GlobalValue::PrivateLinkage, StrConst,
343 static bool GlobalWasGeneratedByAsan(GlobalVariable *G) {
344 return G->getName().find(kAsanGenPrefix) == 0;
347 Value *AddressSanitizer::memToShadow(Value *Shadow, IRBuilder<> &IRB) {
349 Shadow = IRB.CreateLShr(Shadow, MappingScale());
350 if (MappingOffset == 0)
352 // (Shadow >> scale) | offset
353 return IRB.CreateOr(Shadow, ConstantInt::get(IntptrTy,
357 void AddressSanitizer::instrumentMemIntrinsicParam(
358 Instruction *OrigIns,
359 Value *Addr, Value *Size, Instruction *InsertBefore, bool IsWrite) {
360 // Check the first byte.
362 IRBuilder<> IRB(InsertBefore);
363 instrumentAddress(OrigIns, IRB, Addr, 8, IsWrite);
365 // Check the last byte.
367 IRBuilder<> IRB(InsertBefore);
368 Value *SizeMinusOne = IRB.CreateSub(
369 Size, ConstantInt::get(Size->getType(), 1));
370 SizeMinusOne = IRB.CreateIntCast(SizeMinusOne, IntptrTy, false);
371 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
372 Value *AddrPlusSizeMinisOne = IRB.CreateAdd(AddrLong, SizeMinusOne);
373 instrumentAddress(OrigIns, IRB, AddrPlusSizeMinisOne, 8, IsWrite);
377 // Instrument memset/memmove/memcpy
378 bool AddressSanitizer::instrumentMemIntrinsic(MemIntrinsic *MI) {
379 Value *Dst = MI->getDest();
380 MemTransferInst *MemTran = dyn_cast<MemTransferInst>(MI);
381 Value *Src = MemTran ? MemTran->getSource() : 0;
382 Value *Length = MI->getLength();
384 Constant *ConstLength = dyn_cast<Constant>(Length);
385 Instruction *InsertBefore = MI;
387 if (ConstLength->isNullValue()) return false;
389 // The size is not a constant so it could be zero -- check at run-time.
390 IRBuilder<> IRB(InsertBefore);
392 Value *Cmp = IRB.CreateICmpNE(Length,
393 Constant::getNullValue(Length->getType()));
394 InsertBefore = SplitBlockAndInsertIfThen(cast<Instruction>(Cmp), false);
397 instrumentMemIntrinsicParam(MI, Dst, Length, InsertBefore, true);
399 instrumentMemIntrinsicParam(MI, Src, Length, InsertBefore, false);
403 // If I is an interesting memory access, return the PointerOperand
404 // and set IsWrite. Otherwise return NULL.
405 static Value *isInterestingMemoryAccess(Instruction *I, bool *IsWrite) {
406 if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
407 if (!ClInstrumentReads) return NULL;
409 return LI->getPointerOperand();
411 if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
412 if (!ClInstrumentWrites) return NULL;
414 return SI->getPointerOperand();
416 if (AtomicRMWInst *RMW = dyn_cast<AtomicRMWInst>(I)) {
417 if (!ClInstrumentAtomics) return NULL;
419 return RMW->getPointerOperand();
421 if (AtomicCmpXchgInst *XCHG = dyn_cast<AtomicCmpXchgInst>(I)) {
422 if (!ClInstrumentAtomics) return NULL;
424 return XCHG->getPointerOperand();
429 void AddressSanitizer::instrumentMop(Instruction *I) {
430 bool IsWrite = false;
431 Value *Addr = isInterestingMemoryAccess(I, &IsWrite);
433 if (ClOpt && ClOptGlobals) {
434 if (GlobalVariable *G = dyn_cast<GlobalVariable>(Addr)) {
435 // If initialization order checking is disabled, a simple access to a
436 // dynamically initialized global is always valid.
439 // If a global variable does not have dynamic initialization we don't
440 // have to instrument it. However, if a global does not have initailizer
441 // at all, we assume it has dynamic initializer (in other TU).
442 if (G->hasInitializer() && !DynamicallyInitializedGlobals.Contains(G))
447 Type *OrigPtrTy = Addr->getType();
448 Type *OrigTy = cast<PointerType>(OrigPtrTy)->getElementType();
450 assert(OrigTy->isSized());
451 uint32_t TypeSize = TD->getTypeStoreSizeInBits(OrigTy);
453 if (TypeSize != 8 && TypeSize != 16 &&
454 TypeSize != 32 && TypeSize != 64 && TypeSize != 128) {
455 // Ignore all unusual sizes.
460 instrumentAddress(I, IRB, Addr, TypeSize, IsWrite);
463 // Validate the result of Module::getOrInsertFunction called for an interface
464 // function of AddressSanitizer. If the instrumented module defines a function
465 // with the same name, their prototypes must match, otherwise
466 // getOrInsertFunction returns a bitcast.
467 static Function *checkInterfaceFunction(Constant *FuncOrBitcast) {
468 if (isa<Function>(FuncOrBitcast)) return cast<Function>(FuncOrBitcast);
469 FuncOrBitcast->dump();
470 report_fatal_error("trying to redefine an AddressSanitizer "
471 "interface function");
474 Instruction *AddressSanitizer::generateCrashCode(
475 Instruction *InsertBefore, Value *Addr,
476 bool IsWrite, size_t AccessSizeIndex) {
477 IRBuilder<> IRB(InsertBefore);
478 CallInst *Call = IRB.CreateCall(AsanErrorCallback[IsWrite][AccessSizeIndex],
480 // We don't do Call->setDoesNotReturn() because the BB already has
481 // UnreachableInst at the end.
482 // This EmptyAsm is required to avoid callback merge.
483 IRB.CreateCall(EmptyAsm);
487 Value *AddressSanitizer::createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
490 size_t Granularity = 1 << MappingScale();
491 // Addr & (Granularity - 1)
492 Value *LastAccessedByte = IRB.CreateAnd(
493 AddrLong, ConstantInt::get(IntptrTy, Granularity - 1));
494 // (Addr & (Granularity - 1)) + size - 1
495 if (TypeSize / 8 > 1)
496 LastAccessedByte = IRB.CreateAdd(
497 LastAccessedByte, ConstantInt::get(IntptrTy, TypeSize / 8 - 1));
498 // (uint8_t) ((Addr & (Granularity-1)) + size - 1)
499 LastAccessedByte = IRB.CreateIntCast(
500 LastAccessedByte, ShadowValue->getType(), false);
501 // ((uint8_t) ((Addr & (Granularity-1)) + size - 1)) >= ShadowValue
502 return IRB.CreateICmpSGE(LastAccessedByte, ShadowValue);
505 void AddressSanitizer::instrumentAddress(Instruction *OrigIns,
506 IRBuilder<> &IRB, Value *Addr,
507 uint32_t TypeSize, bool IsWrite) {
508 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
510 Type *ShadowTy = IntegerType::get(
511 *C, std::max(8U, TypeSize >> MappingScale()));
512 Type *ShadowPtrTy = PointerType::get(ShadowTy, 0);
513 Value *ShadowPtr = memToShadow(AddrLong, IRB);
514 Value *CmpVal = Constant::getNullValue(ShadowTy);
515 Value *ShadowValue = IRB.CreateLoad(
516 IRB.CreateIntToPtr(ShadowPtr, ShadowPtrTy));
518 Value *Cmp = IRB.CreateICmpNE(ShadowValue, CmpVal);
519 size_t AccessSizeIndex = TypeSizeToSizeIndex(TypeSize);
520 size_t Granularity = 1 << MappingScale();
521 TerminatorInst *CrashTerm = 0;
523 if (ClAlwaysSlowPath || (TypeSize < 8 * Granularity)) {
524 TerminatorInst *CheckTerm =
525 SplitBlockAndInsertIfThen(cast<Instruction>(Cmp), false);
526 assert(dyn_cast<BranchInst>(CheckTerm)->isUnconditional());
527 BasicBlock *NextBB = CheckTerm->getSuccessor(0);
528 IRB.SetInsertPoint(CheckTerm);
529 Value *Cmp2 = createSlowPathCmp(IRB, AddrLong, ShadowValue, TypeSize);
530 BasicBlock *CrashBlock =
531 BasicBlock::Create(*C, "", NextBB->getParent(), NextBB);
532 CrashTerm = new UnreachableInst(*C, CrashBlock);
533 BranchInst *NewTerm = BranchInst::Create(CrashBlock, NextBB, Cmp2);
534 ReplaceInstWithInst(CheckTerm, NewTerm);
536 CrashTerm = SplitBlockAndInsertIfThen(cast<Instruction>(Cmp), true);
540 generateCrashCode(CrashTerm, AddrLong, IsWrite, AccessSizeIndex);
541 Crash->setDebugLoc(OrigIns->getDebugLoc());
544 void AddressSanitizerModule::createInitializerPoisonCalls(
545 Module &M, Value *FirstAddr, Value *LastAddr) {
546 // We do all of our poisoning and unpoisoning within _GLOBAL__I_a.
547 Function *GlobalInit = M.getFunction("_GLOBAL__I_a");
548 // If that function is not present, this TU contains no globals, or they have
549 // all been optimized away
553 // Set up the arguments to our poison/unpoison functions.
554 IRBuilder<> IRB(GlobalInit->begin()->getFirstInsertionPt());
556 // Declare our poisoning and unpoisoning functions.
557 Function *AsanPoisonGlobals = checkInterfaceFunction(M.getOrInsertFunction(
558 kAsanPoisonGlobalsName, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
559 AsanPoisonGlobals->setLinkage(Function::ExternalLinkage);
560 Function *AsanUnpoisonGlobals = checkInterfaceFunction(M.getOrInsertFunction(
561 kAsanUnpoisonGlobalsName, IRB.getVoidTy(), NULL));
562 AsanUnpoisonGlobals->setLinkage(Function::ExternalLinkage);
564 // Add a call to poison all external globals before the given function starts.
565 IRB.CreateCall2(AsanPoisonGlobals, FirstAddr, LastAddr);
567 // Add calls to unpoison all globals before each return instruction.
568 for (Function::iterator I = GlobalInit->begin(), E = GlobalInit->end();
570 if (ReturnInst *RI = dyn_cast<ReturnInst>(I->getTerminator())) {
571 CallInst::Create(AsanUnpoisonGlobals, "", RI);
576 bool AddressSanitizerModule::ShouldInstrumentGlobal(GlobalVariable *G) {
577 Type *Ty = cast<PointerType>(G->getType())->getElementType();
578 DEBUG(dbgs() << "GLOBAL: " << *G << "\n");
580 if (BL->isIn(*G)) return false;
581 if (!Ty->isSized()) return false;
582 if (!G->hasInitializer()) return false;
583 if (GlobalWasGeneratedByAsan(G)) return false; // Our own global.
584 // Touch only those globals that will not be defined in other modules.
585 // Don't handle ODR type linkages since other modules may be built w/o asan.
586 if (G->getLinkage() != GlobalVariable::ExternalLinkage &&
587 G->getLinkage() != GlobalVariable::PrivateLinkage &&
588 G->getLinkage() != GlobalVariable::InternalLinkage)
590 // Two problems with thread-locals:
591 // - The address of the main thread's copy can't be computed at link-time.
592 // - Need to poison all copies, not just the main thread's one.
593 if (G->isThreadLocal())
595 // For now, just ignore this Alloca if the alignment is large.
596 if (G->getAlignment() > RedzoneSize()) return false;
598 // Ignore all the globals with the names starting with "\01L_OBJC_".
599 // Many of those are put into the .cstring section. The linker compresses
600 // that section by removing the spare \0s after the string terminator, so
601 // our redzones get broken.
602 if ((G->getName().find("\01L_OBJC_") == 0) ||
603 (G->getName().find("\01l_OBJC_") == 0)) {
604 DEBUG(dbgs() << "Ignoring \\01L_OBJC_* global: " << *G);
608 if (G->hasSection()) {
609 StringRef Section(G->getSection());
610 // Ignore the globals from the __OBJC section. The ObjC runtime assumes
611 // those conform to /usr/lib/objc/runtime.h, so we can't add redzones to
613 if ((Section.find("__OBJC,") == 0) ||
614 (Section.find("__DATA, __objc_") == 0)) {
615 DEBUG(dbgs() << "Ignoring ObjC runtime global: " << *G);
618 // See http://code.google.com/p/address-sanitizer/issues/detail?id=32
619 // Constant CFString instances are compiled in the following way:
620 // -- the string buffer is emitted into
621 // __TEXT,__cstring,cstring_literals
622 // -- the constant NSConstantString structure referencing that buffer
623 // is placed into __DATA,__cfstring
624 // Therefore there's no point in placing redzones into __DATA,__cfstring.
625 // Moreover, it causes the linker to crash on OS X 10.7
626 if (Section.find("__DATA,__cfstring") == 0) {
627 DEBUG(dbgs() << "Ignoring CFString: " << *G);
635 // This function replaces all global variables with new variables that have
636 // trailing redzones. It also creates a function that poisons
637 // redzones and inserts this function into llvm.global_ctors.
638 bool AddressSanitizerModule::runOnModule(Module &M) {
639 if (!ClGlobals) return false;
640 TD = getAnalysisIfAvailable<DataLayout>();
643 BL.reset(new BlackList(BlacklistFile));
644 if (BL->isIn(M)) return false;
645 DynamicallyInitializedGlobals.Init(M);
646 C = &(M.getContext());
647 IntptrTy = Type::getIntNTy(*C, TD->getPointerSizeInBits());
649 SmallVector<GlobalVariable *, 16> GlobalsToChange;
651 for (Module::GlobalListType::iterator G = M.global_begin(),
652 E = M.global_end(); G != E; ++G) {
653 if (ShouldInstrumentGlobal(G))
654 GlobalsToChange.push_back(G);
657 size_t n = GlobalsToChange.size();
658 if (n == 0) return false;
660 // A global is described by a structure
663 // size_t size_with_redzone;
665 // size_t has_dynamic_init;
666 // We initialize an array of such structures and pass it to a run-time call.
667 StructType *GlobalStructTy = StructType::get(IntptrTy, IntptrTy,
670 SmallVector<Constant *, 16> Initializers(n), DynamicInit;
673 Function *CtorFunc = M.getFunction(kAsanModuleCtorName);
675 IRBuilder<> IRB(CtorFunc->getEntryBlock().getTerminator());
677 // The addresses of the first and last dynamically initialized globals in
678 // this TU. Used in initialization order checking.
679 Value *FirstDynamic = 0, *LastDynamic = 0;
681 for (size_t i = 0; i < n; i++) {
682 GlobalVariable *G = GlobalsToChange[i];
683 PointerType *PtrTy = cast<PointerType>(G->getType());
684 Type *Ty = PtrTy->getElementType();
685 uint64_t SizeInBytes = TD->getTypeAllocSize(Ty);
686 size_t RZ = RedzoneSize();
687 uint64_t RightRedzoneSize = RZ + (RZ - (SizeInBytes % RZ));
688 Type *RightRedZoneTy = ArrayType::get(IRB.getInt8Ty(), RightRedzoneSize);
689 // Determine whether this global should be poisoned in initialization.
690 bool GlobalHasDynamicInitializer =
691 DynamicallyInitializedGlobals.Contains(G);
692 // Don't check initialization order if this global is blacklisted.
693 GlobalHasDynamicInitializer &= !BL->isInInit(*G);
695 StructType *NewTy = StructType::get(Ty, RightRedZoneTy, NULL);
696 Constant *NewInitializer = ConstantStruct::get(
697 NewTy, G->getInitializer(),
698 Constant::getNullValue(RightRedZoneTy), NULL);
700 SmallString<2048> DescriptionOfGlobal = G->getName();
701 DescriptionOfGlobal += " (";
702 DescriptionOfGlobal += M.getModuleIdentifier();
703 DescriptionOfGlobal += ")";
704 GlobalVariable *Name = createPrivateGlobalForString(M, DescriptionOfGlobal);
706 // Create a new global variable with enough space for a redzone.
707 GlobalVariable *NewGlobal = new GlobalVariable(
708 M, NewTy, G->isConstant(), G->getLinkage(),
709 NewInitializer, "", G, G->getThreadLocalMode());
710 NewGlobal->copyAttributesFrom(G);
711 NewGlobal->setAlignment(RZ);
714 Indices2[0] = IRB.getInt32(0);
715 Indices2[1] = IRB.getInt32(0);
717 G->replaceAllUsesWith(
718 ConstantExpr::getGetElementPtr(NewGlobal, Indices2, true));
719 NewGlobal->takeName(G);
720 G->eraseFromParent();
722 Initializers[i] = ConstantStruct::get(
724 ConstantExpr::getPointerCast(NewGlobal, IntptrTy),
725 ConstantInt::get(IntptrTy, SizeInBytes),
726 ConstantInt::get(IntptrTy, SizeInBytes + RightRedzoneSize),
727 ConstantExpr::getPointerCast(Name, IntptrTy),
728 ConstantInt::get(IntptrTy, GlobalHasDynamicInitializer),
731 // Populate the first and last globals declared in this TU.
732 if (CheckInitOrder && GlobalHasDynamicInitializer) {
733 LastDynamic = ConstantExpr::getPointerCast(NewGlobal, IntptrTy);
734 if (FirstDynamic == 0)
735 FirstDynamic = LastDynamic;
738 DEBUG(dbgs() << "NEW GLOBAL: " << *NewGlobal << "\n");
741 ArrayType *ArrayOfGlobalStructTy = ArrayType::get(GlobalStructTy, n);
742 GlobalVariable *AllGlobals = new GlobalVariable(
743 M, ArrayOfGlobalStructTy, false, GlobalVariable::PrivateLinkage,
744 ConstantArray::get(ArrayOfGlobalStructTy, Initializers), "");
746 // Create calls for poisoning before initializers run and unpoisoning after.
747 if (CheckInitOrder && FirstDynamic && LastDynamic)
748 createInitializerPoisonCalls(M, FirstDynamic, LastDynamic);
750 Function *AsanRegisterGlobals = checkInterfaceFunction(M.getOrInsertFunction(
751 kAsanRegisterGlobalsName, IRB.getVoidTy(),
752 IntptrTy, IntptrTy, NULL));
753 AsanRegisterGlobals->setLinkage(Function::ExternalLinkage);
755 IRB.CreateCall2(AsanRegisterGlobals,
756 IRB.CreatePointerCast(AllGlobals, IntptrTy),
757 ConstantInt::get(IntptrTy, n));
759 // We also need to unregister globals at the end, e.g. when a shared library
761 Function *AsanDtorFunction = Function::Create(
762 FunctionType::get(Type::getVoidTy(*C), false),
763 GlobalValue::InternalLinkage, kAsanModuleDtorName, &M);
764 BasicBlock *AsanDtorBB = BasicBlock::Create(*C, "", AsanDtorFunction);
765 IRBuilder<> IRB_Dtor(ReturnInst::Create(*C, AsanDtorBB));
766 Function *AsanUnregisterGlobals =
767 checkInterfaceFunction(M.getOrInsertFunction(
768 kAsanUnregisterGlobalsName,
769 IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
770 AsanUnregisterGlobals->setLinkage(Function::ExternalLinkage);
772 IRB_Dtor.CreateCall2(AsanUnregisterGlobals,
773 IRB.CreatePointerCast(AllGlobals, IntptrTy),
774 ConstantInt::get(IntptrTy, n));
775 appendToGlobalDtors(M, AsanDtorFunction, kAsanCtorAndCtorPriority);
781 void AddressSanitizer::initializeCallbacks(Module &M) {
783 // Create __asan_report* callbacks.
784 for (size_t AccessIsWrite = 0; AccessIsWrite <= 1; AccessIsWrite++) {
785 for (size_t AccessSizeIndex = 0; AccessSizeIndex < kNumberOfAccessSizes;
787 // IsWrite and TypeSize are encoded in the function name.
788 std::string FunctionName = std::string(kAsanReportErrorTemplate) +
789 (AccessIsWrite ? "store" : "load") + itostr(1 << AccessSizeIndex);
790 // If we are merging crash callbacks, they have two parameters.
791 AsanErrorCallback[AccessIsWrite][AccessSizeIndex] =
792 checkInterfaceFunction(M.getOrInsertFunction(
793 FunctionName, IRB.getVoidTy(), IntptrTy, NULL));
797 AsanStackMallocFunc = checkInterfaceFunction(M.getOrInsertFunction(
798 kAsanStackMallocName, IntptrTy, IntptrTy, IntptrTy, NULL));
799 AsanStackFreeFunc = checkInterfaceFunction(M.getOrInsertFunction(
800 kAsanStackFreeName, IRB.getVoidTy(),
801 IntptrTy, IntptrTy, IntptrTy, NULL));
802 AsanHandleNoReturnFunc = checkInterfaceFunction(M.getOrInsertFunction(
803 kAsanHandleNoReturnName, IRB.getVoidTy(), NULL));
804 AsanPoisonStackMemoryFunc = checkInterfaceFunction(M.getOrInsertFunction(
805 kAsanPoisonStackMemoryName, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
806 AsanUnpoisonStackMemoryFunc = checkInterfaceFunction(M.getOrInsertFunction(
807 kAsanUnpoisonStackMemoryName, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
809 // We insert an empty inline asm after __asan_report* to avoid callback merge.
810 EmptyAsm = InlineAsm::get(FunctionType::get(IRB.getVoidTy(), false),
811 StringRef(""), StringRef(""),
812 /*hasSideEffects=*/true);
816 bool AddressSanitizer::doInitialization(Module &M) {
817 // Initialize the private fields. No one has accessed them before.
818 TD = getAnalysisIfAvailable<DataLayout>();
822 BL.reset(new BlackList(BlacklistFile));
823 DynamicallyInitializedGlobals.Init(M);
825 C = &(M.getContext());
826 LongSize = TD->getPointerSizeInBits();
827 IntptrTy = Type::getIntNTy(*C, LongSize);
828 IntptrPtrTy = PointerType::get(IntptrTy, 0);
830 AsanCtorFunction = Function::Create(
831 FunctionType::get(Type::getVoidTy(*C), false),
832 GlobalValue::InternalLinkage, kAsanModuleCtorName, &M);
833 BasicBlock *AsanCtorBB = BasicBlock::Create(*C, "", AsanCtorFunction);
834 // call __asan_init in the module ctor.
835 IRBuilder<> IRB(ReturnInst::Create(*C, AsanCtorBB));
836 AsanInitFunction = checkInterfaceFunction(
837 M.getOrInsertFunction(kAsanInitName, IRB.getVoidTy(), NULL));
838 AsanInitFunction->setLinkage(Function::ExternalLinkage);
839 IRB.CreateCall(AsanInitFunction);
841 llvm::Triple targetTriple(M.getTargetTriple());
842 bool isAndroid = targetTriple.getEnvironment() == llvm::Triple::Android;
844 MappingOffset = isAndroid ? kDefaultShadowOffsetAndroid :
845 (LongSize == 32 ? kDefaultShadowOffset32 : kDefaultShadowOffset64);
846 if (ClMappingOffsetLog >= 0) {
847 if (ClMappingOffsetLog == 0) {
851 MappingOffset = 1ULL << ClMappingOffsetLog;
856 if (ClMappingOffsetLog >= 0) {
857 // Tell the run-time the current values of mapping offset and scale.
858 GlobalValue *asan_mapping_offset =
859 new GlobalVariable(M, IntptrTy, true, GlobalValue::LinkOnceODRLinkage,
860 ConstantInt::get(IntptrTy, MappingOffset),
861 kAsanMappingOffsetName);
862 // Read the global, otherwise it may be optimized away.
863 IRB.CreateLoad(asan_mapping_offset, true);
865 if (ClMappingScale) {
866 GlobalValue *asan_mapping_scale =
867 new GlobalVariable(M, IntptrTy, true, GlobalValue::LinkOnceODRLinkage,
868 ConstantInt::get(IntptrTy, MappingScale()),
869 kAsanMappingScaleName);
870 // Read the global, otherwise it may be optimized away.
871 IRB.CreateLoad(asan_mapping_scale, true);
874 appendToGlobalCtors(M, AsanCtorFunction, kAsanCtorAndCtorPriority);
879 bool AddressSanitizer::maybeInsertAsanInitAtFunctionEntry(Function &F) {
880 // For each NSObject descendant having a +load method, this method is invoked
881 // by the ObjC runtime before any of the static constructors is called.
882 // Therefore we need to instrument such methods with a call to __asan_init
883 // at the beginning in order to initialize our runtime before any access to
884 // the shadow memory.
885 // We cannot just ignore these methods, because they may call other
886 // instrumented functions.
887 if (F.getName().find(" load]") != std::string::npos) {
888 IRBuilder<> IRB(F.begin()->begin());
889 IRB.CreateCall(AsanInitFunction);
895 bool AddressSanitizer::runOnFunction(Function &F) {
896 if (BL->isIn(F)) return false;
897 if (&F == AsanCtorFunction) return false;
898 DEBUG(dbgs() << "ASAN instrumenting:\n" << F << "\n");
899 initializeCallbacks(*F.getParent());
901 // If needed, insert __asan_init before checking for AddressSafety attr.
902 maybeInsertAsanInitAtFunctionEntry(F);
904 if (!F.getFnAttributes().hasAttribute(Attributes::AddressSafety))
907 if (!ClDebugFunc.empty() && ClDebugFunc != F.getName())
910 // We want to instrument every address only once per basic block (unless there
911 // are calls between uses).
912 SmallSet<Value*, 16> TempsToInstrument;
913 SmallVector<Instruction*, 16> ToInstrument;
914 SmallVector<Instruction*, 8> NoReturnCalls;
917 // Fill the set of memory operations to instrument.
918 for (Function::iterator FI = F.begin(), FE = F.end();
920 TempsToInstrument.clear();
921 int NumInsnsPerBB = 0;
922 for (BasicBlock::iterator BI = FI->begin(), BE = FI->end();
924 if (LooksLikeCodeInBug11395(BI)) return false;
925 if (Value *Addr = isInterestingMemoryAccess(BI, &IsWrite)) {
926 if (ClOpt && ClOptSameTemp) {
927 if (!TempsToInstrument.insert(Addr))
928 continue; // We've seen this temp in the current BB.
930 } else if (isa<MemIntrinsic>(BI) && ClMemIntrin) {
933 if (CallInst *CI = dyn_cast<CallInst>(BI)) {
935 TempsToInstrument.clear();
936 if (CI->doesNotReturn()) {
937 NoReturnCalls.push_back(CI);
942 ToInstrument.push_back(BI);
944 if (NumInsnsPerBB >= ClMaxInsnsToInstrumentPerBB)
950 int NumInstrumented = 0;
951 for (size_t i = 0, n = ToInstrument.size(); i != n; i++) {
952 Instruction *Inst = ToInstrument[i];
953 if (ClDebugMin < 0 || ClDebugMax < 0 ||
954 (NumInstrumented >= ClDebugMin && NumInstrumented <= ClDebugMax)) {
955 if (isInterestingMemoryAccess(Inst, &IsWrite))
958 instrumentMemIntrinsic(cast<MemIntrinsic>(Inst));
963 bool ChangedStack = poisonStackInFunction(F);
965 // We must unpoison the stack before every NoReturn call (throw, _exit, etc).
966 // See e.g. http://code.google.com/p/address-sanitizer/issues/detail?id=37
967 for (size_t i = 0, n = NoReturnCalls.size(); i != n; i++) {
968 Instruction *CI = NoReturnCalls[i];
970 IRB.CreateCall(AsanHandleNoReturnFunc);
972 DEBUG(dbgs() << "ASAN done instrumenting:\n" << F << "\n");
974 return NumInstrumented > 0 || ChangedStack || !NoReturnCalls.empty();
977 static uint64_t ValueForPoison(uint64_t PoisonByte, size_t ShadowRedzoneSize) {
978 if (ShadowRedzoneSize == 1) return PoisonByte;
979 if (ShadowRedzoneSize == 2) return (PoisonByte << 8) + PoisonByte;
980 if (ShadowRedzoneSize == 4)
981 return (PoisonByte << 24) + (PoisonByte << 16) +
982 (PoisonByte << 8) + (PoisonByte);
983 llvm_unreachable("ShadowRedzoneSize is either 1, 2 or 4");
986 static void PoisonShadowPartialRightRedzone(uint8_t *Shadow,
989 size_t ShadowGranularity,
991 for (size_t i = 0; i < RZSize;
992 i+= ShadowGranularity, Shadow++) {
993 if (i + ShadowGranularity <= Size) {
994 *Shadow = 0; // fully addressable
995 } else if (i >= Size) {
996 *Shadow = Magic; // unaddressable
998 *Shadow = Size - i; // first Size-i bytes are addressable
1003 void AddressSanitizer::PoisonStack(const ArrayRef<AllocaInst*> &AllocaVec,
1005 Value *ShadowBase, bool DoPoison) {
1006 size_t ShadowRZSize = RedzoneSize() >> MappingScale();
1007 assert(ShadowRZSize >= 1 && ShadowRZSize <= 4);
1008 Type *RZTy = Type::getIntNTy(*C, ShadowRZSize * 8);
1009 Type *RZPtrTy = PointerType::get(RZTy, 0);
1011 Value *PoisonLeft = ConstantInt::get(RZTy,
1012 ValueForPoison(DoPoison ? kAsanStackLeftRedzoneMagic : 0LL, ShadowRZSize));
1013 Value *PoisonMid = ConstantInt::get(RZTy,
1014 ValueForPoison(DoPoison ? kAsanStackMidRedzoneMagic : 0LL, ShadowRZSize));
1015 Value *PoisonRight = ConstantInt::get(RZTy,
1016 ValueForPoison(DoPoison ? kAsanStackRightRedzoneMagic : 0LL, ShadowRZSize));
1018 // poison the first red zone.
1019 IRB.CreateStore(PoisonLeft, IRB.CreateIntToPtr(ShadowBase, RZPtrTy));
1021 // poison all other red zones.
1022 uint64_t Pos = RedzoneSize();
1023 for (size_t i = 0, n = AllocaVec.size(); i < n; i++) {
1024 AllocaInst *AI = AllocaVec[i];
1025 uint64_t SizeInBytes = getAllocaSizeInBytes(AI);
1026 uint64_t AlignedSize = getAlignedAllocaSize(AI);
1027 assert(AlignedSize - SizeInBytes < RedzoneSize());
1032 assert(ShadowBase->getType() == IntptrTy);
1033 if (SizeInBytes < AlignedSize) {
1034 // Poison the partial redzone at right
1035 Ptr = IRB.CreateAdd(
1036 ShadowBase, ConstantInt::get(IntptrTy,
1037 (Pos >> MappingScale()) - ShadowRZSize));
1038 size_t AddressableBytes = RedzoneSize() - (AlignedSize - SizeInBytes);
1039 uint32_t Poison = 0;
1041 PoisonShadowPartialRightRedzone((uint8_t*)&Poison, AddressableBytes,
1043 1ULL << MappingScale(),
1044 kAsanStackPartialRedzoneMagic);
1046 Value *PartialPoison = ConstantInt::get(RZTy, Poison);
1047 IRB.CreateStore(PartialPoison, IRB.CreateIntToPtr(Ptr, RZPtrTy));
1050 // Poison the full redzone at right.
1051 Ptr = IRB.CreateAdd(ShadowBase,
1052 ConstantInt::get(IntptrTy, Pos >> MappingScale()));
1053 Value *Poison = i == AllocaVec.size() - 1 ? PoisonRight : PoisonMid;
1054 IRB.CreateStore(Poison, IRB.CreateIntToPtr(Ptr, RZPtrTy));
1056 Pos += RedzoneSize();
1060 // Workaround for bug 11395: we don't want to instrument stack in functions
1061 // with large assembly blobs (32-bit only), otherwise reg alloc may crash.
1062 // FIXME: remove once the bug 11395 is fixed.
1063 bool AddressSanitizer::LooksLikeCodeInBug11395(Instruction *I) {
1064 if (LongSize != 32) return false;
1065 CallInst *CI = dyn_cast<CallInst>(I);
1066 if (!CI || !CI->isInlineAsm()) return false;
1067 if (CI->getNumArgOperands() <= 5) return false;
1068 // We have inline assembly with quite a few arguments.
1072 // Handling llvm.lifetime intrinsics for a given %alloca:
1073 // (1) collect all llvm.lifetime.xxx(%size, %value) describing the alloca.
1074 // (2) if %size is constant, poison memory for llvm.lifetime.end (to detect
1075 // invalid accesses) and unpoison it for llvm.lifetime.start (the memory
1076 // could be poisoned by previous llvm.lifetime.end instruction, as the
1077 // variable may go in and out of scope several times, e.g. in loops).
1078 // (3) if we poisoned at least one %alloca in a function,
1079 // unpoison the whole stack frame at function exit.
1080 bool AddressSanitizer::handleAllocaLifetime(Value *Alloca) {
1081 assert(CheckLifetime);
1082 Type *AllocaType = Alloca->getType();
1083 Type *Int8PtrTy = Type::getInt8PtrTy(AllocaType->getContext());
1086 // Typical code looks like this:
1087 // %alloca = alloca <type>, <alignment>
1088 // ... some code ...
1089 // %val1 = bitcast <type>* %alloca to i8*
1090 // call void @llvm.lifetime.start(i64 <size>, i8* %val1)
1091 // ... more code ...
1092 // %val2 = bitcast <type>* %alloca to i8*
1093 // call void @llvm.lifetime.start(i64 <size>, i8* %val2)
1094 // That is, to handle %alloca we must find all its casts to
1095 // i8* values, and find lifetime instructions for these values.
1096 if (AllocaType == Int8PtrTy)
1097 Res |= handleValueLifetime(Alloca);
1098 for (Value::use_iterator UI = Alloca->use_begin(), UE = Alloca->use_end();
1100 if (UI->getType() != Int8PtrTy) continue;
1101 if (UI->stripPointerCasts() != Alloca) continue;
1102 Res |= handleValueLifetime(*UI);
1107 bool AddressSanitizer::handleValueLifetime(Value *V) {
1108 assert(CheckLifetime);
1110 for (Value::use_iterator UI = V->use_begin(), UE = V->use_end(); UI != UE;
1112 IntrinsicInst *II = dyn_cast<IntrinsicInst>(*UI);
1114 Intrinsic::ID ID = II->getIntrinsicID();
1115 if (ID != Intrinsic::lifetime_start &&
1116 ID != Intrinsic::lifetime_end)
1118 if (V != II->getArgOperand(1))
1120 // Found lifetime intrinsic, add ASan instrumentation if necessary.
1121 ConstantInt *Size = dyn_cast<ConstantInt>(II->getArgOperand(0));
1122 // If size argument is undefined, don't do anything.
1123 if (Size->isMinusOne())
1125 // Check that size doesn't saturate uint64_t and can
1126 // be stored in IntptrTy.
1127 const uint64_t SizeValue = Size->getValue().getLimitedValue();
1128 if (SizeValue == ~0ULL ||
1129 !ConstantInt::isValueValidForType(IntptrTy, SizeValue)) {
1132 IRBuilder<> IRB(II);
1133 bool DoPoison = (ID == Intrinsic::lifetime_end);
1134 poisonAlloca(V, SizeValue, IRB, DoPoison);
1140 // Find all static Alloca instructions and put
1141 // poisoned red zones around all of them.
1142 // Then unpoison everything back before the function returns.
1144 // Stack poisoning does not play well with exception handling.
1145 // When an exception is thrown, we essentially bypass the code
1146 // that unpoisones the stack. This is why the run-time library has
1147 // to intercept __cxa_throw (as well as longjmp, etc) and unpoison the entire
1148 // stack in the interceptor. This however does not work inside the
1149 // actual function which catches the exception. Most likely because the
1150 // compiler hoists the load of the shadow value somewhere too high.
1151 // This causes asan to report a non-existing bug on 453.povray.
1152 // It sounds like an LLVM bug.
1153 bool AddressSanitizer::poisonStackInFunction(Function &F) {
1154 if (!ClStack) return false;
1155 SmallVector<AllocaInst*, 16> AllocaVec;
1156 SmallVector<Instruction*, 8> RetVec;
1157 uint64_t TotalSize = 0;
1158 bool HavePoisonedAllocas = false;
1160 // Filter out Alloca instructions we want (and can) handle.
1161 // Collect Ret instructions.
1162 for (Function::iterator FI = F.begin(), FE = F.end();
1164 BasicBlock &BB = *FI;
1165 for (BasicBlock::iterator BI = BB.begin(), BE = BB.end();
1167 if (isa<ReturnInst>(BI)) {
1168 RetVec.push_back(BI);
1172 AllocaInst *AI = dyn_cast<AllocaInst>(BI);
1174 if (AI->isArrayAllocation()) continue;
1175 if (!AI->isStaticAlloca()) continue;
1176 if (!AI->getAllocatedType()->isSized()) continue;
1177 if (AI->getAlignment() > RedzoneSize()) continue;
1178 AllocaVec.push_back(AI);
1179 uint64_t AlignedSize = getAlignedAllocaSize(AI);
1180 TotalSize += AlignedSize;
1184 if (AllocaVec.empty()) return false;
1186 uint64_t LocalStackSize = TotalSize + (AllocaVec.size() + 1) * RedzoneSize();
1188 bool DoStackMalloc = CheckUseAfterReturn
1189 && LocalStackSize <= kMaxStackMallocSize;
1191 Instruction *InsBefore = AllocaVec[0];
1192 IRBuilder<> IRB(InsBefore);
1195 Type *ByteArrayTy = ArrayType::get(IRB.getInt8Ty(), LocalStackSize);
1196 AllocaInst *MyAlloca =
1197 new AllocaInst(ByteArrayTy, "MyAlloca", InsBefore);
1198 MyAlloca->setAlignment(RedzoneSize());
1199 assert(MyAlloca->isStaticAlloca());
1200 Value *OrigStackBase = IRB.CreatePointerCast(MyAlloca, IntptrTy);
1201 Value *LocalStackBase = OrigStackBase;
1203 if (DoStackMalloc) {
1204 LocalStackBase = IRB.CreateCall2(AsanStackMallocFunc,
1205 ConstantInt::get(IntptrTy, LocalStackSize), OrigStackBase);
1208 // This string will be parsed by the run-time (DescribeStackAddress).
1209 SmallString<2048> StackDescriptionStorage;
1210 raw_svector_ostream StackDescription(StackDescriptionStorage);
1211 StackDescription << F.getName() << " " << AllocaVec.size() << " ";
1213 uint64_t Pos = RedzoneSize();
1214 // Replace Alloca instructions with base+offset.
1215 for (size_t i = 0, n = AllocaVec.size(); i < n; i++) {
1216 AllocaInst *AI = AllocaVec[i];
1217 uint64_t SizeInBytes = getAllocaSizeInBytes(AI);
1218 StringRef Name = AI->getName();
1219 StackDescription << Pos << " " << SizeInBytes << " "
1220 << Name.size() << " " << Name << " ";
1221 uint64_t AlignedSize = getAlignedAllocaSize(AI);
1222 assert((AlignedSize % RedzoneSize()) == 0);
1223 Value *NewAllocaPtr = IRB.CreateIntToPtr(
1224 IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy, Pos)),
1226 AI->replaceAllUsesWith(NewAllocaPtr);
1227 // Analyze lifetime intrinsics only for static allocas we handle.
1229 HavePoisonedAllocas |= handleAllocaLifetime(NewAllocaPtr);
1230 Pos += AlignedSize + RedzoneSize();
1232 assert(Pos == LocalStackSize);
1234 // Write the Magic value and the frame description constant to the redzone.
1235 Value *BasePlus0 = IRB.CreateIntToPtr(LocalStackBase, IntptrPtrTy);
1236 IRB.CreateStore(ConstantInt::get(IntptrTy, kCurrentStackFrameMagic),
1238 Value *BasePlus1 = IRB.CreateAdd(LocalStackBase,
1239 ConstantInt::get(IntptrTy, LongSize/8));
1240 BasePlus1 = IRB.CreateIntToPtr(BasePlus1, IntptrPtrTy);
1241 GlobalVariable *StackDescriptionGlobal =
1242 createPrivateGlobalForString(*F.getParent(), StackDescription.str());
1243 Value *Description = IRB.CreatePointerCast(StackDescriptionGlobal, IntptrTy);
1244 IRB.CreateStore(Description, BasePlus1);
1246 // Poison the stack redzones at the entry.
1247 Value *ShadowBase = memToShadow(LocalStackBase, IRB);
1248 PoisonStack(ArrayRef<AllocaInst*>(AllocaVec), IRB, ShadowBase, true);
1250 // Unpoison the stack before all ret instructions.
1251 for (size_t i = 0, n = RetVec.size(); i < n; i++) {
1252 Instruction *Ret = RetVec[i];
1253 IRBuilder<> IRBRet(Ret);
1255 // Mark the current frame as retired.
1256 IRBRet.CreateStore(ConstantInt::get(IntptrTy, kRetiredStackFrameMagic),
1258 // Unpoison the stack.
1259 PoisonStack(ArrayRef<AllocaInst*>(AllocaVec), IRBRet, ShadowBase, false);
1261 if (DoStackMalloc) {
1262 // In use-after-return mode, mark the whole stack frame unaddressable.
1263 IRBRet.CreateCall3(AsanStackFreeFunc, LocalStackBase,
1264 ConstantInt::get(IntptrTy, LocalStackSize),
1266 } else if (HavePoisonedAllocas) {
1267 // If we poisoned some allocas in llvm.lifetime analysis,
1268 // unpoison whole stack frame now.
1269 assert(LocalStackBase == OrigStackBase);
1270 poisonAlloca(LocalStackBase, LocalStackSize, IRBRet, false);
1274 // We are done. Remove the old unused alloca instructions.
1275 for (size_t i = 0, n = AllocaVec.size(); i < n; i++)
1276 AllocaVec[i]->eraseFromParent();
1285 void AddressSanitizer::poisonAlloca(Value *V, uint64_t Size, IRBuilder<> IRB,
1287 // For now just insert the call to ASan runtime.
1288 Value *AddrArg = IRB.CreatePointerCast(V, IntptrTy);
1289 Value *SizeArg = ConstantInt::get(IntptrTy, Size);
1290 IRB.CreateCall2(DoPoison ? AsanPoisonStackMemoryFunc
1291 : AsanUnpoisonStackMemoryFunc,