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 "FunctionBlackList.h"
19 #include "llvm/Function.h"
20 #include "llvm/IRBuilder.h"
21 #include "llvm/IntrinsicInst.h"
22 #include "llvm/LLVMContext.h"
23 #include "llvm/Module.h"
24 #include "llvm/Type.h"
25 #include "llvm/ADT/ArrayRef.h"
26 #include "llvm/ADT/OwningPtr.h"
27 #include "llvm/ADT/SmallSet.h"
28 #include "llvm/ADT/SmallString.h"
29 #include "llvm/ADT/SmallVector.h"
30 #include "llvm/ADT/StringExtras.h"
31 #include "llvm/ADT/Triple.h"
32 #include "llvm/Support/CommandLine.h"
33 #include "llvm/Support/DataTypes.h"
34 #include "llvm/Support/Debug.h"
35 #include "llvm/Support/raw_ostream.h"
36 #include "llvm/Support/system_error.h"
37 #include "llvm/Target/TargetData.h"
38 #include "llvm/Target/TargetMachine.h"
39 #include "llvm/Transforms/Instrumentation.h"
40 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
41 #include "llvm/Transforms/Utils/ModuleUtils.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 *kAsanInitName = "__asan_init";
64 static const char *kAsanHandleNoReturnName = "__asan_handle_no_return";
65 static const char *kAsanMappingOffsetName = "__asan_mapping_offset";
66 static const char *kAsanMappingScaleName = "__asan_mapping_scale";
67 static const char *kAsanStackMallocName = "__asan_stack_malloc";
68 static const char *kAsanStackFreeName = "__asan_stack_free";
70 static const int kAsanStackLeftRedzoneMagic = 0xf1;
71 static const int kAsanStackMidRedzoneMagic = 0xf2;
72 static const int kAsanStackRightRedzoneMagic = 0xf3;
73 static const int kAsanStackPartialRedzoneMagic = 0xf4;
75 // Command-line flags.
77 // This flag may need to be replaced with -f[no-]asan-reads.
78 static cl::opt<bool> ClInstrumentReads("asan-instrument-reads",
79 cl::desc("instrument read instructions"), cl::Hidden, cl::init(true));
80 static cl::opt<bool> ClInstrumentWrites("asan-instrument-writes",
81 cl::desc("instrument write instructions"), cl::Hidden, cl::init(true));
82 static cl::opt<bool> ClInstrumentAtomics("asan-instrument-atomics",
83 cl::desc("instrument atomic instructions (rmw, cmpxchg)"),
84 cl::Hidden, cl::init(true));
85 // This flags limits the number of instructions to be instrumented
86 // in any given BB. Normally, this should be set to unlimited (INT_MAX),
87 // but due to http://llvm.org/bugs/show_bug.cgi?id=12652 we temporary
89 static cl::opt<int> ClMaxInsnsToInstrumentPerBB("asan-max-ins-per-bb",
91 cl::desc("maximal number of instructions to instrument in any given BB"),
93 // This flag may need to be replaced with -f[no]asan-stack.
94 static cl::opt<bool> ClStack("asan-stack",
95 cl::desc("Handle stack memory"), cl::Hidden, cl::init(true));
96 // This flag may need to be replaced with -f[no]asan-use-after-return.
97 static cl::opt<bool> ClUseAfterReturn("asan-use-after-return",
98 cl::desc("Check return-after-free"), cl::Hidden, cl::init(false));
99 // This flag may need to be replaced with -f[no]asan-globals.
100 static cl::opt<bool> ClGlobals("asan-globals",
101 cl::desc("Handle global objects"), cl::Hidden, cl::init(true));
102 static cl::opt<bool> ClMemIntrin("asan-memintrin",
103 cl::desc("Handle memset/memcpy/memmove"), cl::Hidden, cl::init(true));
104 // This flag may need to be replaced with -fasan-blacklist.
105 static cl::opt<std::string> ClBlackListFile("asan-blacklist",
106 cl::desc("File containing the list of functions to ignore "
107 "during instrumentation"), cl::Hidden);
109 // These flags allow to change the shadow mapping.
110 // The shadow mapping looks like
111 // Shadow = (Mem >> scale) + (1 << offset_log)
112 static cl::opt<int> ClMappingScale("asan-mapping-scale",
113 cl::desc("scale of asan shadow mapping"), cl::Hidden, cl::init(0));
114 static cl::opt<int> ClMappingOffsetLog("asan-mapping-offset-log",
115 cl::desc("offset of asan shadow mapping"), cl::Hidden, cl::init(-1));
117 // Optimization flags. Not user visible, used mostly for testing
118 // and benchmarking the tool.
119 static cl::opt<bool> ClOpt("asan-opt",
120 cl::desc("Optimize instrumentation"), cl::Hidden, cl::init(true));
121 static cl::opt<bool> ClOptSameTemp("asan-opt-same-temp",
122 cl::desc("Instrument the same temp just once"), cl::Hidden,
124 static cl::opt<bool> ClOptGlobals("asan-opt-globals",
125 cl::desc("Don't instrument scalar globals"), cl::Hidden, cl::init(true));
128 static cl::opt<int> ClDebug("asan-debug", cl::desc("debug"), cl::Hidden,
130 static cl::opt<int> ClDebugStack("asan-debug-stack", cl::desc("debug stack"),
131 cl::Hidden, cl::init(0));
132 static cl::opt<std::string> ClDebugFunc("asan-debug-func",
133 cl::Hidden, cl::desc("Debug func"));
134 static cl::opt<int> ClDebugMin("asan-debug-min", cl::desc("Debug min inst"),
135 cl::Hidden, cl::init(-1));
136 static cl::opt<int> ClDebugMax("asan-debug-max", cl::desc("Debug man inst"),
137 cl::Hidden, cl::init(-1));
141 /// AddressSanitizer: instrument the code in module to find memory bugs.
142 struct AddressSanitizer : public ModulePass {
144 virtual const char *getPassName() const;
145 void instrumentMop(Instruction *I);
146 void instrumentAddress(Instruction *OrigIns, IRBuilder<> &IRB,
147 Value *Addr, uint32_t TypeSize, bool IsWrite);
148 Instruction *generateCrashCode(IRBuilder<> &IRB, Value *Addr,
149 bool IsWrite, uint32_t TypeSize);
150 bool instrumentMemIntrinsic(MemIntrinsic *MI);
151 void instrumentMemIntrinsicParam(Instruction *OrigIns, Value *Addr,
153 Instruction *InsertBefore, bool IsWrite);
154 Value *memToShadow(Value *Shadow, IRBuilder<> &IRB);
155 bool handleFunction(Module &M, Function &F);
156 bool maybeInsertAsanInitAtFunctionEntry(Function &F);
157 bool poisonStackInFunction(Module &M, Function &F);
158 virtual bool runOnModule(Module &M);
159 bool insertGlobalRedzones(Module &M);
160 static char ID; // Pass identification, replacement for typeid
164 uint64_t getAllocaSizeInBytes(AllocaInst *AI) {
165 Type *Ty = AI->getAllocatedType();
166 uint64_t SizeInBytes = TD->getTypeAllocSize(Ty);
169 uint64_t getAlignedSize(uint64_t SizeInBytes) {
170 return ((SizeInBytes + RedzoneSize - 1)
171 / RedzoneSize) * RedzoneSize;
173 uint64_t getAlignedAllocaSize(AllocaInst *AI) {
174 uint64_t SizeInBytes = getAllocaSizeInBytes(AI);
175 return getAlignedSize(SizeInBytes);
178 Function *checkInterfaceFunction(Constant *FuncOrBitcast);
179 void PoisonStack(const ArrayRef<AllocaInst*> &AllocaVec, IRBuilder<> IRB,
180 Value *ShadowBase, bool DoPoison);
181 bool LooksLikeCodeInBug11395(Instruction *I);
185 uint64_t MappingOffset;
191 Function *AsanCtorFunction;
192 Function *AsanInitFunction;
193 Instruction *CtorInsertBefore;
194 OwningPtr<FunctionBlackList> BL;
195 // Accesses sizes are powers of two: 1, 2, 4, 8, 16.
196 static const size_t kNumberOfAccessSizes = 5;
197 // This array is indexed by AccessIsWrite and log2(AccessSize).
198 Function *AsanErrorCallback[2][kNumberOfAccessSizes];
202 char AddressSanitizer::ID = 0;
203 INITIALIZE_PASS(AddressSanitizer, "asan",
204 "AddressSanitizer: detects use-after-free and out-of-bounds bugs.",
206 AddressSanitizer::AddressSanitizer() : ModulePass(ID) { }
207 ModulePass *llvm::createAddressSanitizerPass() {
208 return new AddressSanitizer();
211 const char *AddressSanitizer::getPassName() const {
212 return "AddressSanitizer";
215 // Create a constant for Str so that we can pass it to the run-time lib.
216 static GlobalVariable *createPrivateGlobalForString(Module &M, StringRef Str) {
217 Constant *StrConst = ConstantDataArray::getString(M.getContext(), Str);
218 return new GlobalVariable(M, StrConst->getType(), true,
219 GlobalValue::PrivateLinkage, StrConst, "");
222 // Split the basic block and insert an if-then code.
233 // Returns the ThenBlock's terminator.
234 static BranchInst *splitBlockAndInsertIfThen(Value *Cmp) {
235 Instruction *SplitBefore = cast<Instruction>(Cmp)->getNextNode();
236 BasicBlock *Head = SplitBefore->getParent();
237 BasicBlock *Tail = Head->splitBasicBlock(SplitBefore);
238 TerminatorInst *HeadOldTerm = Head->getTerminator();
239 LLVMContext &C = Head->getParent()->getParent()->getContext();
240 BasicBlock *ThenBlock = BasicBlock::Create(C, "", Head->getParent());
241 BranchInst *HeadNewTerm =
242 BranchInst::Create(/*ifTrue*/ThenBlock, /*ifFalse*/Tail, Cmp);
243 ReplaceInstWithInst(HeadOldTerm, HeadNewTerm);
245 BranchInst *CheckTerm = BranchInst::Create(Tail, ThenBlock);
249 Value *AddressSanitizer::memToShadow(Value *Shadow, IRBuilder<> &IRB) {
251 Shadow = IRB.CreateLShr(Shadow, MappingScale);
252 if (MappingOffset == 0)
254 // (Shadow >> scale) | offset
255 return IRB.CreateOr(Shadow, ConstantInt::get(IntptrTy,
259 void AddressSanitizer::instrumentMemIntrinsicParam(Instruction *OrigIns,
260 Value *Addr, Value *Size, Instruction *InsertBefore, bool IsWrite) {
261 // Check the first byte.
263 IRBuilder<> IRB(InsertBefore);
264 instrumentAddress(OrigIns, IRB, Addr, 8, IsWrite);
266 // Check the last byte.
268 IRBuilder<> IRB(InsertBefore);
269 Value *SizeMinusOne = IRB.CreateSub(
270 Size, ConstantInt::get(Size->getType(), 1));
271 SizeMinusOne = IRB.CreateIntCast(SizeMinusOne, IntptrTy, false);
272 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
273 Value *AddrPlusSizeMinisOne = IRB.CreateAdd(AddrLong, SizeMinusOne);
274 instrumentAddress(OrigIns, IRB, AddrPlusSizeMinisOne, 8, IsWrite);
278 // Instrument memset/memmove/memcpy
279 bool AddressSanitizer::instrumentMemIntrinsic(MemIntrinsic *MI) {
280 Value *Dst = MI->getDest();
281 MemTransferInst *MemTran = dyn_cast<MemTransferInst>(MI);
282 Value *Src = MemTran ? MemTran->getSource() : NULL;
283 Value *Length = MI->getLength();
285 Constant *ConstLength = dyn_cast<Constant>(Length);
286 Instruction *InsertBefore = MI;
288 if (ConstLength->isNullValue()) return false;
290 // The size is not a constant so it could be zero -- check at run-time.
291 IRBuilder<> IRB(InsertBefore);
293 Value *Cmp = IRB.CreateICmpNE(Length,
294 Constant::getNullValue(Length->getType()));
295 InsertBefore = splitBlockAndInsertIfThen(Cmp);
298 instrumentMemIntrinsicParam(MI, Dst, Length, InsertBefore, true);
300 instrumentMemIntrinsicParam(MI, Src, Length, InsertBefore, false);
304 // If I is an interesting memory access, return the PointerOperand
305 // and set IsWrite. Otherwise return NULL.
306 static Value *isInterestingMemoryAccess(Instruction *I, bool *IsWrite) {
307 if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
308 if (!ClInstrumentReads) return NULL;
310 return LI->getPointerOperand();
312 if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
313 if (!ClInstrumentWrites) return NULL;
315 return SI->getPointerOperand();
317 if (AtomicRMWInst *RMW = dyn_cast<AtomicRMWInst>(I)) {
318 if (!ClInstrumentAtomics) return NULL;
320 return RMW->getPointerOperand();
322 if (AtomicCmpXchgInst *XCHG = dyn_cast<AtomicCmpXchgInst>(I)) {
323 if (!ClInstrumentAtomics) return NULL;
325 return XCHG->getPointerOperand();
330 void AddressSanitizer::instrumentMop(Instruction *I) {
332 Value *Addr = isInterestingMemoryAccess(I, &IsWrite);
334 if (ClOpt && ClOptGlobals && isa<GlobalVariable>(Addr)) {
335 // We are accessing a global scalar variable. Nothing to catch here.
338 Type *OrigPtrTy = Addr->getType();
339 Type *OrigTy = cast<PointerType>(OrigPtrTy)->getElementType();
341 assert(OrigTy->isSized());
342 uint32_t TypeSize = TD->getTypeStoreSizeInBits(OrigTy);
344 if (TypeSize != 8 && TypeSize != 16 &&
345 TypeSize != 32 && TypeSize != 64 && TypeSize != 128) {
346 // Ignore all unusual sizes.
351 instrumentAddress(I, IRB, Addr, TypeSize, IsWrite);
354 // Validate the result of Module::getOrInsertFunction called for an interface
355 // function of AddressSanitizer. If the instrumented module defines a function
356 // with the same name, their prototypes must match, otherwise
357 // getOrInsertFunction returns a bitcast.
358 Function *AddressSanitizer::checkInterfaceFunction(Constant *FuncOrBitcast) {
359 if (isa<Function>(FuncOrBitcast)) return cast<Function>(FuncOrBitcast);
360 FuncOrBitcast->dump();
361 report_fatal_error("trying to redefine an AddressSanitizer "
362 "interface function");
365 Instruction *AddressSanitizer::generateCrashCode(
366 IRBuilder<> &IRB, Value *Addr, bool IsWrite, uint32_t TypeSize) {
367 size_t AccessSizeIndex = CountTrailingZeros_32(TypeSize / 8);
368 assert(AccessSizeIndex < kNumberOfAccessSizes);
369 CallInst *Call = IRB.CreateCall(AsanErrorCallback[IsWrite][AccessSizeIndex],
371 Call->setDoesNotReturn();
375 void AddressSanitizer::instrumentAddress(Instruction *OrigIns,
376 IRBuilder<> &IRB, Value *Addr,
377 uint32_t TypeSize, bool IsWrite) {
378 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
380 Type *ShadowTy = IntegerType::get(
381 *C, std::max(8U, TypeSize >> MappingScale));
382 Type *ShadowPtrTy = PointerType::get(ShadowTy, 0);
383 Value *ShadowPtr = memToShadow(AddrLong, IRB);
384 Value *CmpVal = Constant::getNullValue(ShadowTy);
385 Value *ShadowValue = IRB.CreateLoad(
386 IRB.CreateIntToPtr(ShadowPtr, ShadowPtrTy));
388 Value *Cmp = IRB.CreateICmpNE(ShadowValue, CmpVal);
390 Instruction *CheckTerm = splitBlockAndInsertIfThen(Cmp);
391 IRBuilder<> IRB2(CheckTerm);
393 size_t Granularity = 1 << MappingScale;
394 if (TypeSize < 8 * Granularity) {
395 // Addr & (Granularity - 1)
396 Value *LastAccessedByte = IRB2.CreateAnd(
397 AddrLong, ConstantInt::get(IntptrTy, Granularity - 1));
398 // (Addr & (Granularity - 1)) + size - 1
399 if (TypeSize / 8 > 1)
400 LastAccessedByte = IRB2.CreateAdd(
401 LastAccessedByte, ConstantInt::get(IntptrTy, TypeSize / 8 - 1));
402 // (uint8_t) ((Addr & (Granularity-1)) + size - 1)
403 LastAccessedByte = IRB2.CreateIntCast(
404 LastAccessedByte, IRB.getInt8Ty(), false);
405 // ((uint8_t) ((Addr & (Granularity-1)) + size - 1)) >= ShadowValue
406 Value *Cmp2 = IRB2.CreateICmpSGE(LastAccessedByte, ShadowValue);
408 CheckTerm = splitBlockAndInsertIfThen(Cmp2);
411 IRBuilder<> IRB1(CheckTerm);
412 Instruction *Crash = generateCrashCode(IRB1, AddrLong, IsWrite, TypeSize);
413 Crash->setDebugLoc(OrigIns->getDebugLoc());
414 ReplaceInstWithInst(CheckTerm, new UnreachableInst(*C));
417 // This function replaces all global variables with new variables that have
418 // trailing redzones. It also creates a function that poisons
419 // redzones and inserts this function into llvm.global_ctors.
420 bool AddressSanitizer::insertGlobalRedzones(Module &M) {
421 SmallVector<GlobalVariable *, 16> GlobalsToChange;
423 for (Module::GlobalListType::iterator G = M.getGlobalList().begin(),
424 E = M.getGlobalList().end(); G != E; ++G) {
425 Type *Ty = cast<PointerType>(G->getType())->getElementType();
426 DEBUG(dbgs() << "GLOBAL: " << *G);
428 if (!Ty->isSized()) continue;
429 if (!G->hasInitializer()) continue;
430 // Touch only those globals that will not be defined in other modules.
431 // Don't handle ODR type linkages since other modules may be built w/o asan.
432 if (G->getLinkage() != GlobalVariable::ExternalLinkage &&
433 G->getLinkage() != GlobalVariable::PrivateLinkage &&
434 G->getLinkage() != GlobalVariable::InternalLinkage)
436 // Two problems with thread-locals:
437 // - The address of the main thread's copy can't be computed at link-time.
438 // - Need to poison all copies, not just the main thread's one.
439 if (G->isThreadLocal())
441 // For now, just ignore this Alloca if the alignment is large.
442 if (G->getAlignment() > RedzoneSize) continue;
444 // Ignore all the globals with the names starting with "\01L_OBJC_".
445 // Many of those are put into the .cstring section. The linker compresses
446 // that section by removing the spare \0s after the string terminator, so
447 // our redzones get broken.
448 if ((G->getName().find("\01L_OBJC_") == 0) ||
449 (G->getName().find("\01l_OBJC_") == 0)) {
450 DEBUG(dbgs() << "Ignoring \\01L_OBJC_* global: " << *G);
454 if (G->hasSection()) {
455 StringRef Section(G->getSection());
456 // Ignore the globals from the __OBJC section. The ObjC runtime assumes
457 // those conform to /usr/lib/objc/runtime.h, so we can't add redzones to
459 if ((Section.find("__OBJC,") == 0) ||
460 (Section.find("__DATA, __objc_") == 0)) {
461 DEBUG(dbgs() << "Ignoring ObjC runtime global: " << *G);
464 // See http://code.google.com/p/address-sanitizer/issues/detail?id=32
465 // Constant CFString instances are compiled in the following way:
466 // -- the string buffer is emitted into
467 // __TEXT,__cstring,cstring_literals
468 // -- the constant NSConstantString structure referencing that buffer
469 // is placed into __DATA,__cfstring
470 // Therefore there's no point in placing redzones into __DATA,__cfstring.
471 // Moreover, it causes the linker to crash on OS X 10.7
472 if (Section.find("__DATA,__cfstring") == 0) {
473 DEBUG(dbgs() << "Ignoring CFString: " << *G);
478 GlobalsToChange.push_back(G);
481 size_t n = GlobalsToChange.size();
482 if (n == 0) return false;
484 // A global is described by a structure
487 // size_t size_with_redzone;
489 // We initialize an array of such structures and pass it to a run-time call.
490 StructType *GlobalStructTy = StructType::get(IntptrTy, IntptrTy,
491 IntptrTy, IntptrTy, NULL);
492 SmallVector<Constant *, 16> Initializers(n);
494 IRBuilder<> IRB(CtorInsertBefore);
496 for (size_t i = 0; i < n; i++) {
497 GlobalVariable *G = GlobalsToChange[i];
498 PointerType *PtrTy = cast<PointerType>(G->getType());
499 Type *Ty = PtrTy->getElementType();
500 uint64_t SizeInBytes = TD->getTypeAllocSize(Ty);
501 uint64_t RightRedzoneSize = RedzoneSize +
502 (RedzoneSize - (SizeInBytes % RedzoneSize));
503 Type *RightRedZoneTy = ArrayType::get(IRB.getInt8Ty(), RightRedzoneSize);
505 StructType *NewTy = StructType::get(Ty, RightRedZoneTy, NULL);
506 Constant *NewInitializer = ConstantStruct::get(
507 NewTy, G->getInitializer(),
508 Constant::getNullValue(RightRedZoneTy), NULL);
510 SmallString<2048> DescriptionOfGlobal = G->getName();
511 DescriptionOfGlobal += " (";
512 DescriptionOfGlobal += M.getModuleIdentifier();
513 DescriptionOfGlobal += ")";
514 GlobalVariable *Name = createPrivateGlobalForString(M, DescriptionOfGlobal);
516 // Create a new global variable with enough space for a redzone.
517 GlobalVariable *NewGlobal = new GlobalVariable(
518 M, NewTy, G->isConstant(), G->getLinkage(),
519 NewInitializer, "", G, G->getThreadLocalMode());
520 NewGlobal->copyAttributesFrom(G);
521 NewGlobal->setAlignment(RedzoneSize);
524 Indices2[0] = IRB.getInt32(0);
525 Indices2[1] = IRB.getInt32(0);
527 G->replaceAllUsesWith(
528 ConstantExpr::getGetElementPtr(NewGlobal, Indices2, true));
529 NewGlobal->takeName(G);
530 G->eraseFromParent();
532 Initializers[i] = ConstantStruct::get(
534 ConstantExpr::getPointerCast(NewGlobal, IntptrTy),
535 ConstantInt::get(IntptrTy, SizeInBytes),
536 ConstantInt::get(IntptrTy, SizeInBytes + RightRedzoneSize),
537 ConstantExpr::getPointerCast(Name, IntptrTy),
539 DEBUG(dbgs() << "NEW GLOBAL:\n" << *NewGlobal);
542 ArrayType *ArrayOfGlobalStructTy = ArrayType::get(GlobalStructTy, n);
543 GlobalVariable *AllGlobals = new GlobalVariable(
544 M, ArrayOfGlobalStructTy, false, GlobalVariable::PrivateLinkage,
545 ConstantArray::get(ArrayOfGlobalStructTy, Initializers), "");
547 Function *AsanRegisterGlobals = checkInterfaceFunction(M.getOrInsertFunction(
548 kAsanRegisterGlobalsName, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
549 AsanRegisterGlobals->setLinkage(Function::ExternalLinkage);
551 IRB.CreateCall2(AsanRegisterGlobals,
552 IRB.CreatePointerCast(AllGlobals, IntptrTy),
553 ConstantInt::get(IntptrTy, n));
555 // We also need to unregister globals at the end, e.g. when a shared library
557 Function *AsanDtorFunction = Function::Create(
558 FunctionType::get(Type::getVoidTy(*C), false),
559 GlobalValue::InternalLinkage, kAsanModuleDtorName, &M);
560 BasicBlock *AsanDtorBB = BasicBlock::Create(*C, "", AsanDtorFunction);
561 IRBuilder<> IRB_Dtor(ReturnInst::Create(*C, AsanDtorBB));
562 Function *AsanUnregisterGlobals =
563 checkInterfaceFunction(M.getOrInsertFunction(
564 kAsanUnregisterGlobalsName,
565 IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
566 AsanUnregisterGlobals->setLinkage(Function::ExternalLinkage);
568 IRB_Dtor.CreateCall2(AsanUnregisterGlobals,
569 IRB.CreatePointerCast(AllGlobals, IntptrTy),
570 ConstantInt::get(IntptrTy, n));
571 appendToGlobalDtors(M, AsanDtorFunction, kAsanCtorAndCtorPriority);
578 bool AddressSanitizer::runOnModule(Module &M) {
579 // Initialize the private fields. No one has accessed them before.
580 TD = getAnalysisIfAvailable<TargetData>();
583 BL.reset(new FunctionBlackList(ClBlackListFile));
585 C = &(M.getContext());
586 LongSize = TD->getPointerSizeInBits();
587 IntptrTy = Type::getIntNTy(*C, LongSize);
588 IntptrPtrTy = PointerType::get(IntptrTy, 0);
590 AsanCtorFunction = Function::Create(
591 FunctionType::get(Type::getVoidTy(*C), false),
592 GlobalValue::InternalLinkage, kAsanModuleCtorName, &M);
593 BasicBlock *AsanCtorBB = BasicBlock::Create(*C, "", AsanCtorFunction);
594 CtorInsertBefore = ReturnInst::Create(*C, AsanCtorBB);
596 // call __asan_init in the module ctor.
597 IRBuilder<> IRB(CtorInsertBefore);
598 AsanInitFunction = checkInterfaceFunction(
599 M.getOrInsertFunction(kAsanInitName, IRB.getVoidTy(), NULL));
600 AsanInitFunction->setLinkage(Function::ExternalLinkage);
601 IRB.CreateCall(AsanInitFunction);
603 // Create __asan_report* callbacks.
604 for (size_t AccessIsWrite = 0; AccessIsWrite <= 1; AccessIsWrite++) {
605 for (size_t AccessSizeIndex = 0; AccessSizeIndex < kNumberOfAccessSizes;
607 // IsWrite and TypeSize are encoded in the function name.
608 std::string FunctionName = std::string(kAsanReportErrorTemplate) +
609 (AccessIsWrite ? "store" : "load") + itostr(1 << AccessSizeIndex);
610 AsanErrorCallback[AccessIsWrite][AccessSizeIndex] = cast<Function>(
611 M.getOrInsertFunction(FunctionName, IRB.getVoidTy(), IntptrTy, NULL));
615 llvm::Triple targetTriple(M.getTargetTriple());
616 bool isAndroid = targetTriple.getEnvironment() == llvm::Triple::ANDROIDEABI;
618 MappingOffset = isAndroid ? kDefaultShadowOffsetAndroid :
619 (LongSize == 32 ? kDefaultShadowOffset32 : kDefaultShadowOffset64);
620 if (ClMappingOffsetLog >= 0) {
621 if (ClMappingOffsetLog == 0) {
625 MappingOffset = 1ULL << ClMappingOffsetLog;
628 MappingScale = kDefaultShadowScale;
629 if (ClMappingScale) {
630 MappingScale = ClMappingScale;
632 // Redzone used for stack and globals is at least 32 bytes.
633 // For scales 6 and 7, the redzone has to be 64 and 128 bytes respectively.
634 RedzoneSize = std::max(32, (int)(1 << MappingScale));
639 Res |= insertGlobalRedzones(M);
641 if (ClMappingOffsetLog >= 0) {
642 // Tell the run-time the current values of mapping offset and scale.
643 GlobalValue *asan_mapping_offset =
644 new GlobalVariable(M, IntptrTy, true, GlobalValue::LinkOnceODRLinkage,
645 ConstantInt::get(IntptrTy, MappingOffset),
646 kAsanMappingOffsetName);
647 // Read the global, otherwise it may be optimized away.
648 IRB.CreateLoad(asan_mapping_offset, true);
650 if (ClMappingScale) {
651 GlobalValue *asan_mapping_scale =
652 new GlobalVariable(M, IntptrTy, true, GlobalValue::LinkOnceODRLinkage,
653 ConstantInt::get(IntptrTy, MappingScale),
654 kAsanMappingScaleName);
655 // Read the global, otherwise it may be optimized away.
656 IRB.CreateLoad(asan_mapping_scale, true);
660 for (Module::iterator F = M.begin(), E = M.end(); F != E; ++F) {
661 if (F->isDeclaration()) continue;
662 Res |= handleFunction(M, *F);
665 appendToGlobalCtors(M, AsanCtorFunction, kAsanCtorAndCtorPriority);
670 bool AddressSanitizer::maybeInsertAsanInitAtFunctionEntry(Function &F) {
671 // For each NSObject descendant having a +load method, this method is invoked
672 // by the ObjC runtime before any of the static constructors is called.
673 // Therefore we need to instrument such methods with a call to __asan_init
674 // at the beginning in order to initialize our runtime before any access to
675 // the shadow memory.
676 // We cannot just ignore these methods, because they may call other
677 // instrumented functions.
678 if (F.getName().find(" load]") != std::string::npos) {
679 IRBuilder<> IRB(F.begin()->begin());
680 IRB.CreateCall(AsanInitFunction);
686 bool AddressSanitizer::handleFunction(Module &M, Function &F) {
687 if (BL->isIn(F)) return false;
688 if (&F == AsanCtorFunction) return false;
690 // If needed, insert __asan_init before checking for AddressSafety attr.
691 maybeInsertAsanInitAtFunctionEntry(F);
693 if (!F.hasFnAttr(Attribute::AddressSafety)) return false;
695 if (!ClDebugFunc.empty() && ClDebugFunc != F.getName())
697 // We want to instrument every address only once per basic block
698 // (unless there are calls between uses).
699 SmallSet<Value*, 16> TempsToInstrument;
700 SmallVector<Instruction*, 16> ToInstrument;
701 SmallVector<Instruction*, 8> NoReturnCalls;
704 // Fill the set of memory operations to instrument.
705 for (Function::iterator FI = F.begin(), FE = F.end();
707 TempsToInstrument.clear();
708 int NumInsnsPerBB = 0;
709 for (BasicBlock::iterator BI = FI->begin(), BE = FI->end();
711 if (LooksLikeCodeInBug11395(BI)) return false;
712 if (Value *Addr = isInterestingMemoryAccess(BI, &IsWrite)) {
713 if (ClOpt && ClOptSameTemp) {
714 if (!TempsToInstrument.insert(Addr))
715 continue; // We've seen this temp in the current BB.
717 } else if (isa<MemIntrinsic>(BI) && ClMemIntrin) {
720 if (CallInst *CI = dyn_cast<CallInst>(BI)) {
722 TempsToInstrument.clear();
723 if (CI->doesNotReturn()) {
724 NoReturnCalls.push_back(CI);
729 ToInstrument.push_back(BI);
731 if (NumInsnsPerBB >= ClMaxInsnsToInstrumentPerBB)
737 int NumInstrumented = 0;
738 for (size_t i = 0, n = ToInstrument.size(); i != n; i++) {
739 Instruction *Inst = ToInstrument[i];
740 if (ClDebugMin < 0 || ClDebugMax < 0 ||
741 (NumInstrumented >= ClDebugMin && NumInstrumented <= ClDebugMax)) {
742 if (isInterestingMemoryAccess(Inst, &IsWrite))
745 instrumentMemIntrinsic(cast<MemIntrinsic>(Inst));
752 bool ChangedStack = poisonStackInFunction(M, F);
754 // We must unpoison the stack before every NoReturn call (throw, _exit, etc).
755 // See e.g. http://code.google.com/p/address-sanitizer/issues/detail?id=37
756 for (size_t i = 0, n = NoReturnCalls.size(); i != n; i++) {
757 Instruction *CI = NoReturnCalls[i];
759 IRB.CreateCall(M.getOrInsertFunction(kAsanHandleNoReturnName,
760 IRB.getVoidTy(), NULL));
763 return NumInstrumented > 0 || ChangedStack || !NoReturnCalls.empty();
766 static uint64_t ValueForPoison(uint64_t PoisonByte, size_t ShadowRedzoneSize) {
767 if (ShadowRedzoneSize == 1) return PoisonByte;
768 if (ShadowRedzoneSize == 2) return (PoisonByte << 8) + PoisonByte;
769 if (ShadowRedzoneSize == 4)
770 return (PoisonByte << 24) + (PoisonByte << 16) +
771 (PoisonByte << 8) + (PoisonByte);
772 llvm_unreachable("ShadowRedzoneSize is either 1, 2 or 4");
775 static void PoisonShadowPartialRightRedzone(uint8_t *Shadow,
778 size_t ShadowGranularity,
780 for (size_t i = 0; i < RedzoneSize;
781 i+= ShadowGranularity, Shadow++) {
782 if (i + ShadowGranularity <= Size) {
783 *Shadow = 0; // fully addressable
784 } else if (i >= Size) {
785 *Shadow = Magic; // unaddressable
787 *Shadow = Size - i; // first Size-i bytes are addressable
792 void AddressSanitizer::PoisonStack(const ArrayRef<AllocaInst*> &AllocaVec,
794 Value *ShadowBase, bool DoPoison) {
795 size_t ShadowRZSize = RedzoneSize >> MappingScale;
796 assert(ShadowRZSize >= 1 && ShadowRZSize <= 4);
797 Type *RZTy = Type::getIntNTy(*C, ShadowRZSize * 8);
798 Type *RZPtrTy = PointerType::get(RZTy, 0);
800 Value *PoisonLeft = ConstantInt::get(RZTy,
801 ValueForPoison(DoPoison ? kAsanStackLeftRedzoneMagic : 0LL, ShadowRZSize));
802 Value *PoisonMid = ConstantInt::get(RZTy,
803 ValueForPoison(DoPoison ? kAsanStackMidRedzoneMagic : 0LL, ShadowRZSize));
804 Value *PoisonRight = ConstantInt::get(RZTy,
805 ValueForPoison(DoPoison ? kAsanStackRightRedzoneMagic : 0LL, ShadowRZSize));
807 // poison the first red zone.
808 IRB.CreateStore(PoisonLeft, IRB.CreateIntToPtr(ShadowBase, RZPtrTy));
810 // poison all other red zones.
811 uint64_t Pos = RedzoneSize;
812 for (size_t i = 0, n = AllocaVec.size(); i < n; i++) {
813 AllocaInst *AI = AllocaVec[i];
814 uint64_t SizeInBytes = getAllocaSizeInBytes(AI);
815 uint64_t AlignedSize = getAlignedAllocaSize(AI);
816 assert(AlignedSize - SizeInBytes < RedzoneSize);
821 assert(ShadowBase->getType() == IntptrTy);
822 if (SizeInBytes < AlignedSize) {
823 // Poison the partial redzone at right
825 ShadowBase, ConstantInt::get(IntptrTy,
826 (Pos >> MappingScale) - ShadowRZSize));
827 size_t AddressableBytes = RedzoneSize - (AlignedSize - SizeInBytes);
830 PoisonShadowPartialRightRedzone((uint8_t*)&Poison, AddressableBytes,
832 1ULL << MappingScale,
833 kAsanStackPartialRedzoneMagic);
835 Value *PartialPoison = ConstantInt::get(RZTy, Poison);
836 IRB.CreateStore(PartialPoison, IRB.CreateIntToPtr(Ptr, RZPtrTy));
839 // Poison the full redzone at right.
840 Ptr = IRB.CreateAdd(ShadowBase,
841 ConstantInt::get(IntptrTy, Pos >> MappingScale));
842 Value *Poison = i == AllocaVec.size() - 1 ? PoisonRight : PoisonMid;
843 IRB.CreateStore(Poison, IRB.CreateIntToPtr(Ptr, RZPtrTy));
849 // Workaround for bug 11395: we don't want to instrument stack in functions
850 // with large assembly blobs (32-bit only), otherwise reg alloc may crash.
851 // FIXME: remove once the bug 11395 is fixed.
852 bool AddressSanitizer::LooksLikeCodeInBug11395(Instruction *I) {
853 if (LongSize != 32) return false;
854 CallInst *CI = dyn_cast<CallInst>(I);
855 if (!CI || !CI->isInlineAsm()) return false;
856 if (CI->getNumArgOperands() <= 5) return false;
857 // We have inline assembly with quite a few arguments.
861 // Find all static Alloca instructions and put
862 // poisoned red zones around all of them.
863 // Then unpoison everything back before the function returns.
865 // Stack poisoning does not play well with exception handling.
866 // When an exception is thrown, we essentially bypass the code
867 // that unpoisones the stack. This is why the run-time library has
868 // to intercept __cxa_throw (as well as longjmp, etc) and unpoison the entire
869 // stack in the interceptor. This however does not work inside the
870 // actual function which catches the exception. Most likely because the
871 // compiler hoists the load of the shadow value somewhere too high.
872 // This causes asan to report a non-existing bug on 453.povray.
873 // It sounds like an LLVM bug.
874 bool AddressSanitizer::poisonStackInFunction(Module &M, Function &F) {
875 if (!ClStack) return false;
876 SmallVector<AllocaInst*, 16> AllocaVec;
877 SmallVector<Instruction*, 8> RetVec;
878 uint64_t TotalSize = 0;
880 // Filter out Alloca instructions we want (and can) handle.
881 // Collect Ret instructions.
882 for (Function::iterator FI = F.begin(), FE = F.end();
884 BasicBlock &BB = *FI;
885 for (BasicBlock::iterator BI = BB.begin(), BE = BB.end();
887 if (isa<ReturnInst>(BI)) {
888 RetVec.push_back(BI);
892 AllocaInst *AI = dyn_cast<AllocaInst>(BI);
894 if (AI->isArrayAllocation()) continue;
895 if (!AI->isStaticAlloca()) continue;
896 if (!AI->getAllocatedType()->isSized()) continue;
897 if (AI->getAlignment() > RedzoneSize) continue;
898 AllocaVec.push_back(AI);
899 uint64_t AlignedSize = getAlignedAllocaSize(AI);
900 TotalSize += AlignedSize;
904 if (AllocaVec.empty()) return false;
906 uint64_t LocalStackSize = TotalSize + (AllocaVec.size() + 1) * RedzoneSize;
908 bool DoStackMalloc = ClUseAfterReturn
909 && LocalStackSize <= kMaxStackMallocSize;
911 Instruction *InsBefore = AllocaVec[0];
912 IRBuilder<> IRB(InsBefore);
915 Type *ByteArrayTy = ArrayType::get(IRB.getInt8Ty(), LocalStackSize);
916 AllocaInst *MyAlloca =
917 new AllocaInst(ByteArrayTy, "MyAlloca", InsBefore);
918 MyAlloca->setAlignment(RedzoneSize);
919 assert(MyAlloca->isStaticAlloca());
920 Value *OrigStackBase = IRB.CreatePointerCast(MyAlloca, IntptrTy);
921 Value *LocalStackBase = OrigStackBase;
924 Value *AsanStackMallocFunc = M.getOrInsertFunction(
925 kAsanStackMallocName, IntptrTy, IntptrTy, IntptrTy, NULL);
926 LocalStackBase = IRB.CreateCall2(AsanStackMallocFunc,
927 ConstantInt::get(IntptrTy, LocalStackSize), OrigStackBase);
930 // This string will be parsed by the run-time (DescribeStackAddress).
931 SmallString<2048> StackDescriptionStorage;
932 raw_svector_ostream StackDescription(StackDescriptionStorage);
933 StackDescription << F.getName() << " " << AllocaVec.size() << " ";
935 uint64_t Pos = RedzoneSize;
936 // Replace Alloca instructions with base+offset.
937 for (size_t i = 0, n = AllocaVec.size(); i < n; i++) {
938 AllocaInst *AI = AllocaVec[i];
939 uint64_t SizeInBytes = getAllocaSizeInBytes(AI);
940 StringRef Name = AI->getName();
941 StackDescription << Pos << " " << SizeInBytes << " "
942 << Name.size() << " " << Name << " ";
943 uint64_t AlignedSize = getAlignedAllocaSize(AI);
944 assert((AlignedSize % RedzoneSize) == 0);
945 AI->replaceAllUsesWith(
947 IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy, Pos)),
949 Pos += AlignedSize + RedzoneSize;
951 assert(Pos == LocalStackSize);
953 // Write the Magic value and the frame description constant to the redzone.
954 Value *BasePlus0 = IRB.CreateIntToPtr(LocalStackBase, IntptrPtrTy);
955 IRB.CreateStore(ConstantInt::get(IntptrTy, kCurrentStackFrameMagic),
957 Value *BasePlus1 = IRB.CreateAdd(LocalStackBase,
958 ConstantInt::get(IntptrTy, LongSize/8));
959 BasePlus1 = IRB.CreateIntToPtr(BasePlus1, IntptrPtrTy);
960 Value *Description = IRB.CreatePointerCast(
961 createPrivateGlobalForString(M, StackDescription.str()),
963 IRB.CreateStore(Description, BasePlus1);
965 // Poison the stack redzones at the entry.
966 Value *ShadowBase = memToShadow(LocalStackBase, IRB);
967 PoisonStack(ArrayRef<AllocaInst*>(AllocaVec), IRB, ShadowBase, true);
969 Value *AsanStackFreeFunc = NULL;
971 AsanStackFreeFunc = M.getOrInsertFunction(
972 kAsanStackFreeName, IRB.getVoidTy(),
973 IntptrTy, IntptrTy, IntptrTy, NULL);
976 // Unpoison the stack before all ret instructions.
977 for (size_t i = 0, n = RetVec.size(); i < n; i++) {
978 Instruction *Ret = RetVec[i];
979 IRBuilder<> IRBRet(Ret);
981 // Mark the current frame as retired.
982 IRBRet.CreateStore(ConstantInt::get(IntptrTy, kRetiredStackFrameMagic),
984 // Unpoison the stack.
985 PoisonStack(ArrayRef<AllocaInst*>(AllocaVec), IRBRet, ShadowBase, false);
988 IRBRet.CreateCall3(AsanStackFreeFunc, LocalStackBase,
989 ConstantInt::get(IntptrTy, LocalStackSize),