| //===-- AddressSanitizer.cpp - memory error detector ------------*- C++ -*-===// |
| // |
| // The LLVM Compiler Infrastructure |
| // |
| // This file is distributed under the University of Illinois Open Source |
| // License. See LICENSE.TXT for details. |
| // |
| //===----------------------------------------------------------------------===// |
| // |
| // This file is a part of AddressSanitizer, an address sanity checker. |
| // Details of the algorithm: |
| // http://code.google.com/p/address-sanitizer/wiki/AddressSanitizerAlgorithm |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #define DEBUG_TYPE "asan" |
| |
| #include "FunctionBlackList.h" |
| #include "llvm/ADT/ArrayRef.h" |
| #include "llvm/ADT/OwningPtr.h" |
| #include "llvm/ADT/SmallSet.h" |
| #include "llvm/ADT/SmallString.h" |
| #include "llvm/ADT/SmallVector.h" |
| #include "llvm/ADT/StringExtras.h" |
| #include "llvm/Function.h" |
| #include "llvm/IntrinsicInst.h" |
| #include "llvm/LLVMContext.h" |
| #include "llvm/Module.h" |
| #include "llvm/Support/CommandLine.h" |
| #include "llvm/Support/DataTypes.h" |
| #include "llvm/Support/Debug.h" |
| #include "llvm/Support/IRBuilder.h" |
| #include "llvm/Support/raw_ostream.h" |
| #include "llvm/Support/system_error.h" |
| #include "llvm/Target/TargetData.h" |
| #include "llvm/Target/TargetMachine.h" |
| #include "llvm/Transforms/Instrumentation.h" |
| #include "llvm/Transforms/Utils/BasicBlockUtils.h" |
| #include "llvm/Transforms/Utils/ModuleUtils.h" |
| #include "llvm/Type.h" |
| |
| #include <string> |
| #include <algorithm> |
| |
| using namespace llvm; |
| |
| static const uint64_t kDefaultShadowScale = 3; |
| static const uint64_t kDefaultShadowOffset32 = 1ULL << 29; |
| static const uint64_t kDefaultShadowOffset64 = 1ULL << 44; |
| |
| static const size_t kMaxStackMallocSize = 1 << 16; // 64K |
| static const uintptr_t kCurrentStackFrameMagic = 0x41B58AB3; |
| static const uintptr_t kRetiredStackFrameMagic = 0x45E0360E; |
| |
| static const char *kAsanModuleCtorName = "asan.module_ctor"; |
| static const char *kAsanModuleDtorName = "asan.module_dtor"; |
| static const int kAsanCtorAndCtorPriority = 1; |
| static const char *kAsanReportErrorTemplate = "__asan_report_"; |
| static const char *kAsanRegisterGlobalsName = "__asan_register_globals"; |
| static const char *kAsanUnregisterGlobalsName = "__asan_unregister_globals"; |
| static const char *kAsanInitName = "__asan_init"; |
| static const char *kAsanHandleNoReturnName = "__asan_handle_no_return"; |
| static const char *kAsanMappingOffsetName = "__asan_mapping_offset"; |
| static const char *kAsanMappingScaleName = "__asan_mapping_scale"; |
| static const char *kAsanStackMallocName = "__asan_stack_malloc"; |
| static const char *kAsanStackFreeName = "__asan_stack_free"; |
| |
| static const int kAsanStackLeftRedzoneMagic = 0xf1; |
| static const int kAsanStackMidRedzoneMagic = 0xf2; |
| static const int kAsanStackRightRedzoneMagic = 0xf3; |
| static const int kAsanStackPartialRedzoneMagic = 0xf4; |
| |
| // Command-line flags. |
| |
| // This flag may need to be replaced with -f[no-]asan-reads. |
| static cl::opt<bool> ClInstrumentReads("asan-instrument-reads", |
| cl::desc("instrument read instructions"), cl::Hidden, cl::init(true)); |
| static cl::opt<bool> ClInstrumentWrites("asan-instrument-writes", |
| cl::desc("instrument write instructions"), cl::Hidden, cl::init(true)); |
| // This flag may need to be replaced with -f[no]asan-stack. |
| static cl::opt<bool> ClStack("asan-stack", |
| cl::desc("Handle stack memory"), cl::Hidden, cl::init(true)); |
| // This flag may need to be replaced with -f[no]asan-use-after-return. |
| static cl::opt<bool> ClUseAfterReturn("asan-use-after-return", |
| cl::desc("Check return-after-free"), cl::Hidden, cl::init(false)); |
| // This flag may need to be replaced with -f[no]asan-globals. |
| static cl::opt<bool> ClGlobals("asan-globals", |
| cl::desc("Handle global objects"), cl::Hidden, cl::init(true)); |
| static cl::opt<bool> ClMemIntrin("asan-memintrin", |
| cl::desc("Handle memset/memcpy/memmove"), cl::Hidden, cl::init(true)); |
| // This flag may need to be replaced with -fasan-blacklist. |
| static cl::opt<std::string> ClBlackListFile("asan-blacklist", |
| cl::desc("File containing the list of functions to ignore " |
| "during instrumentation"), cl::Hidden); |
| |
| // These flags allow to change the shadow mapping. |
| // The shadow mapping looks like |
| // Shadow = (Mem >> scale) + (1 << offset_log) |
| static cl::opt<int> ClMappingScale("asan-mapping-scale", |
| cl::desc("scale of asan shadow mapping"), cl::Hidden, cl::init(0)); |
| static cl::opt<int> ClMappingOffsetLog("asan-mapping-offset-log", |
| cl::desc("offset of asan shadow mapping"), cl::Hidden, cl::init(-1)); |
| |
| // Optimization flags. Not user visible, used mostly for testing |
| // and benchmarking the tool. |
| static cl::opt<bool> ClOpt("asan-opt", |
| cl::desc("Optimize instrumentation"), cl::Hidden, cl::init(true)); |
| static cl::opt<bool> ClOptSameTemp("asan-opt-same-temp", |
| cl::desc("Instrument the same temp just once"), cl::Hidden, |
| cl::init(true)); |
| static cl::opt<bool> ClOptGlobals("asan-opt-globals", |
| cl::desc("Don't instrument scalar globals"), cl::Hidden, cl::init(true)); |
| |
| // Debug flags. |
| static cl::opt<int> ClDebug("asan-debug", cl::desc("debug"), cl::Hidden, |
| cl::init(0)); |
| static cl::opt<int> ClDebugStack("asan-debug-stack", cl::desc("debug stack"), |
| cl::Hidden, cl::init(0)); |
| static cl::opt<std::string> ClDebugFunc("asan-debug-func", |
| cl::Hidden, cl::desc("Debug func")); |
| static cl::opt<int> ClDebugMin("asan-debug-min", cl::desc("Debug min inst"), |
| cl::Hidden, cl::init(-1)); |
| static cl::opt<int> ClDebugMax("asan-debug-max", cl::desc("Debug man inst"), |
| cl::Hidden, cl::init(-1)); |
| |
| namespace { |
| |
| /// AddressSanitizer: instrument the code in module to find memory bugs. |
| struct AddressSanitizer : public ModulePass { |
| AddressSanitizer(); |
| virtual const char *getPassName() const; |
| void instrumentMop(Instruction *I); |
| void instrumentAddress(Instruction *OrigIns, IRBuilder<> &IRB, |
| Value *Addr, uint32_t TypeSize, bool IsWrite); |
| Instruction *generateCrashCode(IRBuilder<> &IRB, Value *Addr, |
| bool IsWrite, uint32_t TypeSize); |
| bool instrumentMemIntrinsic(MemIntrinsic *MI); |
| void instrumentMemIntrinsicParam(Instruction *OrigIns, Value *Addr, |
| Value *Size, |
| Instruction *InsertBefore, bool IsWrite); |
| Value *memToShadow(Value *Shadow, IRBuilder<> &IRB); |
| bool handleFunction(Module &M, Function &F); |
| bool maybeInsertAsanInitAtFunctionEntry(Function &F); |
| bool poisonStackInFunction(Module &M, Function &F); |
| virtual bool runOnModule(Module &M); |
| bool insertGlobalRedzones(Module &M); |
| BranchInst *splitBlockAndInsertIfThen(Instruction *SplitBefore, Value *Cmp); |
| static char ID; // Pass identification, replacement for typeid |
| |
| private: |
| |
| uint64_t getAllocaSizeInBytes(AllocaInst *AI) { |
| Type *Ty = AI->getAllocatedType(); |
| uint64_t SizeInBytes = TD->getTypeAllocSize(Ty); |
| return SizeInBytes; |
| } |
| uint64_t getAlignedSize(uint64_t SizeInBytes) { |
| return ((SizeInBytes + RedzoneSize - 1) |
| / RedzoneSize) * RedzoneSize; |
| } |
| uint64_t getAlignedAllocaSize(AllocaInst *AI) { |
| uint64_t SizeInBytes = getAllocaSizeInBytes(AI); |
| return getAlignedSize(SizeInBytes); |
| } |
| |
| void PoisonStack(const ArrayRef<AllocaInst*> &AllocaVec, IRBuilder<> IRB, |
| Value *ShadowBase, bool DoPoison); |
| bool LooksLikeCodeInBug11395(Instruction *I); |
| |
| Module *CurrentModule; |
| LLVMContext *C; |
| TargetData *TD; |
| uint64_t MappingOffset; |
| int MappingScale; |
| size_t RedzoneSize; |
| int LongSize; |
| Type *IntptrTy; |
| Type *IntptrPtrTy; |
| Function *AsanCtorFunction; |
| Function *AsanInitFunction; |
| Instruction *CtorInsertBefore; |
| OwningPtr<FunctionBlackList> BL; |
| }; |
| } // namespace |
| |
| char AddressSanitizer::ID = 0; |
| INITIALIZE_PASS(AddressSanitizer, "asan", |
| "AddressSanitizer: detects use-after-free and out-of-bounds bugs.", |
| false, false) |
| AddressSanitizer::AddressSanitizer() : ModulePass(ID) { } |
| ModulePass *llvm::createAddressSanitizerPass() { |
| return new AddressSanitizer(); |
| } |
| |
| const char *AddressSanitizer::getPassName() const { |
| return "AddressSanitizer"; |
| } |
| |
| // Create a constant for Str so that we can pass it to the run-time lib. |
| static GlobalVariable *createPrivateGlobalForString(Module &M, StringRef Str) { |
| Constant *StrConst = ConstantDataArray::getString(M.getContext(), Str); |
| return new GlobalVariable(M, StrConst->getType(), true, |
| GlobalValue::PrivateLinkage, StrConst, ""); |
| } |
| |
| // Split the basic block and insert an if-then code. |
| // Before: |
| // Head |
| // SplitBefore |
| // Tail |
| // After: |
| // Head |
| // if (Cmp) |
| // NewBasicBlock |
| // SplitBefore |
| // Tail |
| // |
| // Returns the NewBasicBlock's terminator. |
| BranchInst *AddressSanitizer::splitBlockAndInsertIfThen( |
| Instruction *SplitBefore, Value *Cmp) { |
| BasicBlock *Head = SplitBefore->getParent(); |
| BasicBlock *Tail = Head->splitBasicBlock(SplitBefore); |
| TerminatorInst *HeadOldTerm = Head->getTerminator(); |
| BasicBlock *NewBasicBlock = |
| BasicBlock::Create(*C, "", Head->getParent()); |
| BranchInst *HeadNewTerm = BranchInst::Create(/*ifTrue*/NewBasicBlock, |
| /*ifFalse*/Tail, |
| Cmp); |
| ReplaceInstWithInst(HeadOldTerm, HeadNewTerm); |
| |
| BranchInst *CheckTerm = BranchInst::Create(Tail, NewBasicBlock); |
| return CheckTerm; |
| } |
| |
| Value *AddressSanitizer::memToShadow(Value *Shadow, IRBuilder<> &IRB) { |
| // Shadow >> scale |
| Shadow = IRB.CreateLShr(Shadow, MappingScale); |
| if (MappingOffset == 0) |
| return Shadow; |
| // (Shadow >> scale) | offset |
| return IRB.CreateOr(Shadow, ConstantInt::get(IntptrTy, |
| MappingOffset)); |
| } |
| |
| void AddressSanitizer::instrumentMemIntrinsicParam(Instruction *OrigIns, |
| Value *Addr, Value *Size, Instruction *InsertBefore, bool IsWrite) { |
| // Check the first byte. |
| { |
| IRBuilder<> IRB(InsertBefore); |
| instrumentAddress(OrigIns, IRB, Addr, 8, IsWrite); |
| } |
| // Check the last byte. |
| { |
| IRBuilder<> IRB(InsertBefore); |
| Value *SizeMinusOne = IRB.CreateSub( |
| Size, ConstantInt::get(Size->getType(), 1)); |
| SizeMinusOne = IRB.CreateIntCast(SizeMinusOne, IntptrTy, false); |
| Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy); |
| Value *AddrPlusSizeMinisOne = IRB.CreateAdd(AddrLong, SizeMinusOne); |
| instrumentAddress(OrigIns, IRB, AddrPlusSizeMinisOne, 8, IsWrite); |
| } |
| } |
| |
| // Instrument memset/memmove/memcpy |
| bool AddressSanitizer::instrumentMemIntrinsic(MemIntrinsic *MI) { |
| Value *Dst = MI->getDest(); |
| MemTransferInst *MemTran = dyn_cast<MemTransferInst>(MI); |
| Value *Src = MemTran ? MemTran->getSource() : NULL; |
| Value *Length = MI->getLength(); |
| |
| Constant *ConstLength = dyn_cast<Constant>(Length); |
| Instruction *InsertBefore = MI; |
| if (ConstLength) { |
| if (ConstLength->isNullValue()) return false; |
| } else { |
| // The size is not a constant so it could be zero -- check at run-time. |
| IRBuilder<> IRB(InsertBefore); |
| |
| Value *Cmp = IRB.CreateICmpNE(Length, |
| Constant::getNullValue(Length->getType())); |
| InsertBefore = splitBlockAndInsertIfThen(InsertBefore, Cmp); |
| } |
| |
| instrumentMemIntrinsicParam(MI, Dst, Length, InsertBefore, true); |
| if (Src) |
| instrumentMemIntrinsicParam(MI, Src, Length, InsertBefore, false); |
| return true; |
| } |
| |
| static Value *getLDSTOperand(Instruction *I) { |
| if (LoadInst *LI = dyn_cast<LoadInst>(I)) { |
| return LI->getPointerOperand(); |
| } |
| return cast<StoreInst>(*I).getPointerOperand(); |
| } |
| |
| void AddressSanitizer::instrumentMop(Instruction *I) { |
| int IsWrite = isa<StoreInst>(*I); |
| Value *Addr = getLDSTOperand(I); |
| if (ClOpt && ClOptGlobals && isa<GlobalVariable>(Addr)) { |
| // We are accessing a global scalar variable. Nothing to catch here. |
| return; |
| } |
| Type *OrigPtrTy = Addr->getType(); |
| Type *OrigTy = cast<PointerType>(OrigPtrTy)->getElementType(); |
| |
| assert(OrigTy->isSized()); |
| uint32_t TypeSize = TD->getTypeStoreSizeInBits(OrigTy); |
| |
| if (TypeSize != 8 && TypeSize != 16 && |
| TypeSize != 32 && TypeSize != 64 && TypeSize != 128) { |
| // Ignore all unusual sizes. |
| return; |
| } |
| |
| IRBuilder<> IRB(I); |
| instrumentAddress(I, IRB, Addr, TypeSize, IsWrite); |
| } |
| |
| Instruction *AddressSanitizer::generateCrashCode( |
| IRBuilder<> &IRB, Value *Addr, bool IsWrite, uint32_t TypeSize) { |
| // IsWrite and TypeSize are encoded in the function name. |
| std::string FunctionName = std::string(kAsanReportErrorTemplate) + |
| (IsWrite ? "store" : "load") + itostr(TypeSize / 8); |
| Value *ReportWarningFunc = CurrentModule->getOrInsertFunction( |
| FunctionName, IRB.getVoidTy(), IntptrTy, NULL); |
| CallInst *Call = IRB.CreateCall(ReportWarningFunc, Addr); |
| Call->setDoesNotReturn(); |
| return Call; |
| } |
| |
| void AddressSanitizer::instrumentAddress(Instruction *OrigIns, |
| IRBuilder<> &IRB, Value *Addr, |
| uint32_t TypeSize, bool IsWrite) { |
| Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy); |
| |
| Type *ShadowTy = IntegerType::get( |
| *C, std::max(8U, TypeSize >> MappingScale)); |
| Type *ShadowPtrTy = PointerType::get(ShadowTy, 0); |
| Value *ShadowPtr = memToShadow(AddrLong, IRB); |
| Value *CmpVal = Constant::getNullValue(ShadowTy); |
| Value *ShadowValue = IRB.CreateLoad( |
| IRB.CreateIntToPtr(ShadowPtr, ShadowPtrTy)); |
| |
| Value *Cmp = IRB.CreateICmpNE(ShadowValue, CmpVal); |
| |
| Instruction *CheckTerm = splitBlockAndInsertIfThen( |
| cast<Instruction>(Cmp)->getNextNode(), Cmp); |
| IRBuilder<> IRB2(CheckTerm); |
| |
| size_t Granularity = 1 << MappingScale; |
| if (TypeSize < 8 * Granularity) { |
| // Addr & (Granularity - 1) |
| Value *Lower3Bits = IRB2.CreateAnd( |
| AddrLong, ConstantInt::get(IntptrTy, Granularity - 1)); |
| // (Addr & (Granularity - 1)) + size - 1 |
| Value *LastAccessedByte = IRB2.CreateAdd( |
| Lower3Bits, ConstantInt::get(IntptrTy, TypeSize / 8 - 1)); |
| // (uint8_t) ((Addr & (Granularity-1)) + size - 1) |
| LastAccessedByte = IRB2.CreateIntCast( |
| LastAccessedByte, IRB.getInt8Ty(), false); |
| // ((uint8_t) ((Addr & (Granularity-1)) + size - 1)) >= ShadowValue |
| Value *Cmp2 = IRB2.CreateICmpSGE(LastAccessedByte, ShadowValue); |
| |
| CheckTerm = splitBlockAndInsertIfThen(CheckTerm, Cmp2); |
| } |
| |
| IRBuilder<> IRB1(CheckTerm); |
| Instruction *Crash = generateCrashCode(IRB1, AddrLong, IsWrite, TypeSize); |
| Crash->setDebugLoc(OrigIns->getDebugLoc()); |
| ReplaceInstWithInst(CheckTerm, new UnreachableInst(*C)); |
| } |
| |
| // This function replaces all global variables with new variables that have |
| // trailing redzones. It also creates a function that poisons |
| // redzones and inserts this function into llvm.global_ctors. |
| bool AddressSanitizer::insertGlobalRedzones(Module &M) { |
| SmallVector<GlobalVariable *, 16> GlobalsToChange; |
| |
| for (Module::GlobalListType::iterator G = M.getGlobalList().begin(), |
| E = M.getGlobalList().end(); G != E; ++G) { |
| Type *Ty = cast<PointerType>(G->getType())->getElementType(); |
| DEBUG(dbgs() << "GLOBAL: " << *G); |
| |
| if (!Ty->isSized()) continue; |
| if (!G->hasInitializer()) continue; |
| // Touch only those globals that will not be defined in other modules. |
| // Don't handle ODR type linkages since other modules may be built w/o asan. |
| if (G->getLinkage() != GlobalVariable::ExternalLinkage && |
| G->getLinkage() != GlobalVariable::PrivateLinkage && |
| G->getLinkage() != GlobalVariable::InternalLinkage) |
| continue; |
| // Two problems with thread-locals: |
| // - The address of the main thread's copy can't be computed at link-time. |
| // - Need to poison all copies, not just the main thread's one. |
| if (G->isThreadLocal()) |
| continue; |
| // For now, just ignore this Alloca if the alignment is large. |
| if (G->getAlignment() > RedzoneSize) continue; |
| |
| // Ignore all the globals with the names starting with "\01L_OBJC_". |
| // Many of those are put into the .cstring section. The linker compresses |
| // that section by removing the spare \0s after the string terminator, so |
| // our redzones get broken. |
| if ((G->getName().find("\01L_OBJC_") == 0) || |
| (G->getName().find("\01l_OBJC_") == 0)) { |
| DEBUG(dbgs() << "Ignoring \\01L_OBJC_* global: " << *G); |
| continue; |
| } |
| |
| if (G->hasSection()) { |
| StringRef Section(G->getSection()); |
| // Ignore the globals from the __OBJC section. The ObjC runtime assumes |
| // those conform to /usr/lib/objc/runtime.h, so we can't add redzones to |
| // them. |
| if ((Section.find("__OBJC,") == 0) || |
| (Section.find("__DATA, __objc_") == 0)) { |
| DEBUG(dbgs() << "Ignoring ObjC runtime global: " << *G); |
| continue; |
| } |
| // See http://code.google.com/p/address-sanitizer/issues/detail?id=32 |
| // Constant CFString instances are compiled in the following way: |
| // -- the string buffer is emitted into |
| // __TEXT,__cstring,cstring_literals |
| // -- the constant NSConstantString structure referencing that buffer |
| // is placed into __DATA,__cfstring |
| // Therefore there's no point in placing redzones into __DATA,__cfstring. |
| // Moreover, it causes the linker to crash on OS X 10.7 |
| if (Section.find("__DATA,__cfstring") == 0) { |
| DEBUG(dbgs() << "Ignoring CFString: " << *G); |
| continue; |
| } |
| } |
| |
| GlobalsToChange.push_back(G); |
| } |
| |
| size_t n = GlobalsToChange.size(); |
| if (n == 0) return false; |
| |
| // A global is described by a structure |
| // size_t beg; |
| // size_t size; |
| // size_t size_with_redzone; |
| // const char *name; |
| // We initialize an array of such structures and pass it to a run-time call. |
| StructType *GlobalStructTy = StructType::get(IntptrTy, IntptrTy, |
| IntptrTy, IntptrTy, NULL); |
| SmallVector<Constant *, 16> Initializers(n); |
| |
| IRBuilder<> IRB(CtorInsertBefore); |
| |
| for (size_t i = 0; i < n; i++) { |
| GlobalVariable *G = GlobalsToChange[i]; |
| PointerType *PtrTy = cast<PointerType>(G->getType()); |
| Type *Ty = PtrTy->getElementType(); |
| uint64_t SizeInBytes = TD->getTypeAllocSize(Ty); |
| uint64_t RightRedzoneSize = RedzoneSize + |
| (RedzoneSize - (SizeInBytes % RedzoneSize)); |
| Type *RightRedZoneTy = ArrayType::get(IRB.getInt8Ty(), RightRedzoneSize); |
| |
| StructType *NewTy = StructType::get(Ty, RightRedZoneTy, NULL); |
| Constant *NewInitializer = ConstantStruct::get( |
| NewTy, G->getInitializer(), |
| Constant::getNullValue(RightRedZoneTy), NULL); |
| |
| SmallString<2048> DescriptionOfGlobal = G->getName(); |
| DescriptionOfGlobal += " ("; |
| DescriptionOfGlobal += M.getModuleIdentifier(); |
| DescriptionOfGlobal += ")"; |
| GlobalVariable *Name = createPrivateGlobalForString(M, DescriptionOfGlobal); |
| |
| // Create a new global variable with enough space for a redzone. |
| GlobalVariable *NewGlobal = new GlobalVariable( |
| M, NewTy, G->isConstant(), G->getLinkage(), |
| NewInitializer, "", G, G->isThreadLocal()); |
| NewGlobal->copyAttributesFrom(G); |
| NewGlobal->setAlignment(RedzoneSize); |
| |
| Value *Indices2[2]; |
| Indices2[0] = IRB.getInt32(0); |
| Indices2[1] = IRB.getInt32(0); |
| |
| G->replaceAllUsesWith( |
| ConstantExpr::getGetElementPtr(NewGlobal, Indices2, true)); |
| NewGlobal->takeName(G); |
| G->eraseFromParent(); |
| |
| Initializers[i] = ConstantStruct::get( |
| GlobalStructTy, |
| ConstantExpr::getPointerCast(NewGlobal, IntptrTy), |
| ConstantInt::get(IntptrTy, SizeInBytes), |
| ConstantInt::get(IntptrTy, SizeInBytes + RightRedzoneSize), |
| ConstantExpr::getPointerCast(Name, IntptrTy), |
| NULL); |
| DEBUG(dbgs() << "NEW GLOBAL:\n" << *NewGlobal); |
| } |
| |
| ArrayType *ArrayOfGlobalStructTy = ArrayType::get(GlobalStructTy, n); |
| GlobalVariable *AllGlobals = new GlobalVariable( |
| M, ArrayOfGlobalStructTy, false, GlobalVariable::PrivateLinkage, |
| ConstantArray::get(ArrayOfGlobalStructTy, Initializers), ""); |
| |
| Function *AsanRegisterGlobals = cast<Function>(M.getOrInsertFunction( |
| kAsanRegisterGlobalsName, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL)); |
| AsanRegisterGlobals->setLinkage(Function::ExternalLinkage); |
| |
| IRB.CreateCall2(AsanRegisterGlobals, |
| IRB.CreatePointerCast(AllGlobals, IntptrTy), |
| ConstantInt::get(IntptrTy, n)); |
| |
| // We also need to unregister globals at the end, e.g. when a shared library |
| // gets closed. |
| Function *AsanDtorFunction = Function::Create( |
| FunctionType::get(Type::getVoidTy(*C), false), |
| GlobalValue::InternalLinkage, kAsanModuleDtorName, &M); |
| BasicBlock *AsanDtorBB = BasicBlock::Create(*C, "", AsanDtorFunction); |
| IRBuilder<> IRB_Dtor(ReturnInst::Create(*C, AsanDtorBB)); |
| Function *AsanUnregisterGlobals = cast<Function>(M.getOrInsertFunction( |
| kAsanUnregisterGlobalsName, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL)); |
| AsanUnregisterGlobals->setLinkage(Function::ExternalLinkage); |
| |
| IRB_Dtor.CreateCall2(AsanUnregisterGlobals, |
| IRB.CreatePointerCast(AllGlobals, IntptrTy), |
| ConstantInt::get(IntptrTy, n)); |
| appendToGlobalDtors(M, AsanDtorFunction, kAsanCtorAndCtorPriority); |
| |
| DEBUG(dbgs() << M); |
| return true; |
| } |
| |
| // virtual |
| bool AddressSanitizer::runOnModule(Module &M) { |
| // Initialize the private fields. No one has accessed them before. |
| TD = getAnalysisIfAvailable<TargetData>(); |
| if (!TD) |
| return false; |
| BL.reset(new FunctionBlackList(ClBlackListFile)); |
| |
| CurrentModule = &M; |
| C = &(M.getContext()); |
| LongSize = TD->getPointerSizeInBits(); |
| IntptrTy = Type::getIntNTy(*C, LongSize); |
| IntptrPtrTy = PointerType::get(IntptrTy, 0); |
| |
| AsanCtorFunction = Function::Create( |
| FunctionType::get(Type::getVoidTy(*C), false), |
| GlobalValue::InternalLinkage, kAsanModuleCtorName, &M); |
| BasicBlock *AsanCtorBB = BasicBlock::Create(*C, "", AsanCtorFunction); |
| CtorInsertBefore = ReturnInst::Create(*C, AsanCtorBB); |
| |
| // call __asan_init in the module ctor. |
| IRBuilder<> IRB(CtorInsertBefore); |
| AsanInitFunction = cast<Function>( |
| M.getOrInsertFunction(kAsanInitName, IRB.getVoidTy(), NULL)); |
| AsanInitFunction->setLinkage(Function::ExternalLinkage); |
| IRB.CreateCall(AsanInitFunction); |
| |
| MappingOffset = LongSize == 32 |
| ? kDefaultShadowOffset32 : kDefaultShadowOffset64; |
| if (ClMappingOffsetLog >= 0) { |
| if (ClMappingOffsetLog == 0) { |
| // special case |
| MappingOffset = 0; |
| } else { |
| MappingOffset = 1ULL << ClMappingOffsetLog; |
| } |
| } |
| MappingScale = kDefaultShadowScale; |
| if (ClMappingScale) { |
| MappingScale = ClMappingScale; |
| } |
| // Redzone used for stack and globals is at least 32 bytes. |
| // For scales 6 and 7, the redzone has to be 64 and 128 bytes respectively. |
| RedzoneSize = std::max(32, (int)(1 << MappingScale)); |
| |
| bool Res = false; |
| |
| if (ClGlobals) |
| Res |= insertGlobalRedzones(M); |
| |
| if (ClMappingOffsetLog >= 0) { |
| // Tell the run-time the current values of mapping offset and scale. |
| GlobalValue *asan_mapping_offset = |
| new GlobalVariable(M, IntptrTy, true, GlobalValue::LinkOnceODRLinkage, |
| ConstantInt::get(IntptrTy, MappingOffset), |
| kAsanMappingOffsetName); |
| // Read the global, otherwise it may be optimized away. |
| IRB.CreateLoad(asan_mapping_offset, true); |
| } |
| if (ClMappingScale) { |
| GlobalValue *asan_mapping_scale = |
| new GlobalVariable(M, IntptrTy, true, GlobalValue::LinkOnceODRLinkage, |
| ConstantInt::get(IntptrTy, MappingScale), |
| kAsanMappingScaleName); |
| // Read the global, otherwise it may be optimized away. |
| IRB.CreateLoad(asan_mapping_scale, true); |
| } |
| |
| |
| for (Module::iterator F = M.begin(), E = M.end(); F != E; ++F) { |
| if (F->isDeclaration()) continue; |
| Res |= handleFunction(M, *F); |
| } |
| |
| appendToGlobalCtors(M, AsanCtorFunction, kAsanCtorAndCtorPriority); |
| |
| return Res; |
| } |
| |
| bool AddressSanitizer::maybeInsertAsanInitAtFunctionEntry(Function &F) { |
| // For each NSObject descendant having a +load method, this method is invoked |
| // by the ObjC runtime before any of the static constructors is called. |
| // Therefore we need to instrument such methods with a call to __asan_init |
| // at the beginning in order to initialize our runtime before any access to |
| // the shadow memory. |
| // We cannot just ignore these methods, because they may call other |
| // instrumented functions. |
| if (F.getName().find(" load]") != std::string::npos) { |
| IRBuilder<> IRB(F.begin()->begin()); |
| IRB.CreateCall(AsanInitFunction); |
| return true; |
| } |
| return false; |
| } |
| |
| bool AddressSanitizer::handleFunction(Module &M, Function &F) { |
| if (BL->isIn(F)) return false; |
| if (&F == AsanCtorFunction) return false; |
| |
| // If needed, insert __asan_init before checking for AddressSafety attr. |
| maybeInsertAsanInitAtFunctionEntry(F); |
| |
| if (!F.hasFnAttr(Attribute::AddressSafety)) return false; |
| |
| if (!ClDebugFunc.empty() && ClDebugFunc != F.getName()) |
| return false; |
| // We want to instrument every address only once per basic block |
| // (unless there are calls between uses). |
| SmallSet<Value*, 16> TempsToInstrument; |
| SmallVector<Instruction*, 16> ToInstrument; |
| SmallVector<Instruction*, 8> NoReturnCalls; |
| |
| // Fill the set of memory operations to instrument. |
| for (Function::iterator FI = F.begin(), FE = F.end(); |
| FI != FE; ++FI) { |
| TempsToInstrument.clear(); |
| for (BasicBlock::iterator BI = FI->begin(), BE = FI->end(); |
| BI != BE; ++BI) { |
| if (LooksLikeCodeInBug11395(BI)) return false; |
| if ((isa<LoadInst>(BI) && ClInstrumentReads) || |
| (isa<StoreInst>(BI) && ClInstrumentWrites)) { |
| Value *Addr = getLDSTOperand(BI); |
| if (ClOpt && ClOptSameTemp) { |
| if (!TempsToInstrument.insert(Addr)) |
| continue; // We've seen this temp in the current BB. |
| } |
| } else if (isa<MemIntrinsic>(BI) && ClMemIntrin) { |
| // ok, take it. |
| } else { |
| if (CallInst *CI = dyn_cast<CallInst>(BI)) { |
| // A call inside BB. |
| TempsToInstrument.clear(); |
| if (CI->doesNotReturn()) { |
| NoReturnCalls.push_back(CI); |
| } |
| } |
| continue; |
| } |
| ToInstrument.push_back(BI); |
| } |
| } |
| |
| // Instrument. |
| int NumInstrumented = 0; |
| for (size_t i = 0, n = ToInstrument.size(); i != n; i++) { |
| Instruction *Inst = ToInstrument[i]; |
| if (ClDebugMin < 0 || ClDebugMax < 0 || |
| (NumInstrumented >= ClDebugMin && NumInstrumented <= ClDebugMax)) { |
| if (isa<StoreInst>(Inst) || isa<LoadInst>(Inst)) |
| instrumentMop(Inst); |
| else |
| instrumentMemIntrinsic(cast<MemIntrinsic>(Inst)); |
| } |
| NumInstrumented++; |
| } |
| |
| DEBUG(dbgs() << F); |
| |
| bool ChangedStack = poisonStackInFunction(M, F); |
| |
| // We must unpoison the stack before every NoReturn call (throw, _exit, etc). |
| // See e.g. http://code.google.com/p/address-sanitizer/issues/detail?id=37 |
| for (size_t i = 0, n = NoReturnCalls.size(); i != n; i++) { |
| Instruction *CI = NoReturnCalls[i]; |
| IRBuilder<> IRB(CI); |
| IRB.CreateCall(M.getOrInsertFunction(kAsanHandleNoReturnName, |
| IRB.getVoidTy(), NULL)); |
| } |
| |
| return NumInstrumented > 0 || ChangedStack || !NoReturnCalls.empty(); |
| } |
| |
| static uint64_t ValueForPoison(uint64_t PoisonByte, size_t ShadowRedzoneSize) { |
| if (ShadowRedzoneSize == 1) return PoisonByte; |
| if (ShadowRedzoneSize == 2) return (PoisonByte << 8) + PoisonByte; |
| if (ShadowRedzoneSize == 4) |
| return (PoisonByte << 24) + (PoisonByte << 16) + |
| (PoisonByte << 8) + (PoisonByte); |
| llvm_unreachable("ShadowRedzoneSize is either 1, 2 or 4"); |
| } |
| |
| static void PoisonShadowPartialRightRedzone(uint8_t *Shadow, |
| size_t Size, |
| size_t RedzoneSize, |
| size_t ShadowGranularity, |
| uint8_t Magic) { |
| for (size_t i = 0; i < RedzoneSize; |
| i+= ShadowGranularity, Shadow++) { |
| if (i + ShadowGranularity <= Size) { |
| *Shadow = 0; // fully addressable |
| } else if (i >= Size) { |
| *Shadow = Magic; // unaddressable |
| } else { |
| *Shadow = Size - i; // first Size-i bytes are addressable |
| } |
| } |
| } |
| |
| void AddressSanitizer::PoisonStack(const ArrayRef<AllocaInst*> &AllocaVec, |
| IRBuilder<> IRB, |
| Value *ShadowBase, bool DoPoison) { |
| size_t ShadowRZSize = RedzoneSize >> MappingScale; |
| assert(ShadowRZSize >= 1 && ShadowRZSize <= 4); |
| Type *RZTy = Type::getIntNTy(*C, ShadowRZSize * 8); |
| Type *RZPtrTy = PointerType::get(RZTy, 0); |
| |
| Value *PoisonLeft = ConstantInt::get(RZTy, |
| ValueForPoison(DoPoison ? kAsanStackLeftRedzoneMagic : 0LL, ShadowRZSize)); |
| Value *PoisonMid = ConstantInt::get(RZTy, |
| ValueForPoison(DoPoison ? kAsanStackMidRedzoneMagic : 0LL, ShadowRZSize)); |
| Value *PoisonRight = ConstantInt::get(RZTy, |
| ValueForPoison(DoPoison ? kAsanStackRightRedzoneMagic : 0LL, ShadowRZSize)); |
| |
| // poison the first red zone. |
| IRB.CreateStore(PoisonLeft, IRB.CreateIntToPtr(ShadowBase, RZPtrTy)); |
| |
| // poison all other red zones. |
| uint64_t Pos = RedzoneSize; |
| for (size_t i = 0, n = AllocaVec.size(); i < n; i++) { |
| AllocaInst *AI = AllocaVec[i]; |
| uint64_t SizeInBytes = getAllocaSizeInBytes(AI); |
| uint64_t AlignedSize = getAlignedAllocaSize(AI); |
| assert(AlignedSize - SizeInBytes < RedzoneSize); |
| Value *Ptr = NULL; |
| |
| Pos += AlignedSize; |
| |
| assert(ShadowBase->getType() == IntptrTy); |
| if (SizeInBytes < AlignedSize) { |
| // Poison the partial redzone at right |
| Ptr = IRB.CreateAdd( |
| ShadowBase, ConstantInt::get(IntptrTy, |
| (Pos >> MappingScale) - ShadowRZSize)); |
| size_t AddressableBytes = RedzoneSize - (AlignedSize - SizeInBytes); |
| uint32_t Poison = 0; |
| if (DoPoison) { |
| PoisonShadowPartialRightRedzone((uint8_t*)&Poison, AddressableBytes, |
| RedzoneSize, |
| 1ULL << MappingScale, |
| kAsanStackPartialRedzoneMagic); |
| } |
| Value *PartialPoison = ConstantInt::get(RZTy, Poison); |
| IRB.CreateStore(PartialPoison, IRB.CreateIntToPtr(Ptr, RZPtrTy)); |
| } |
| |
| // Poison the full redzone at right. |
| Ptr = IRB.CreateAdd(ShadowBase, |
| ConstantInt::get(IntptrTy, Pos >> MappingScale)); |
| Value *Poison = i == AllocaVec.size() - 1 ? PoisonRight : PoisonMid; |
| IRB.CreateStore(Poison, IRB.CreateIntToPtr(Ptr, RZPtrTy)); |
| |
| Pos += RedzoneSize; |
| } |
| } |
| |
| // Workaround for bug 11395: we don't want to instrument stack in functions |
| // with large assembly blobs (32-bit only), otherwise reg alloc may crash. |
| // FIXME: remove once the bug 11395 is fixed. |
| bool AddressSanitizer::LooksLikeCodeInBug11395(Instruction *I) { |
| if (LongSize != 32) return false; |
| CallInst *CI = dyn_cast<CallInst>(I); |
| if (!CI || !CI->isInlineAsm()) return false; |
| if (CI->getNumArgOperands() <= 5) return false; |
| // We have inline assembly with quite a few arguments. |
| return true; |
| } |
| |
| // Find all static Alloca instructions and put |
| // poisoned red zones around all of them. |
| // Then unpoison everything back before the function returns. |
| // |
| // Stack poisoning does not play well with exception handling. |
| // When an exception is thrown, we essentially bypass the code |
| // that unpoisones the stack. This is why the run-time library has |
| // to intercept __cxa_throw (as well as longjmp, etc) and unpoison the entire |
| // stack in the interceptor. This however does not work inside the |
| // actual function which catches the exception. Most likely because the |
| // compiler hoists the load of the shadow value somewhere too high. |
| // This causes asan to report a non-existing bug on 453.povray. |
| // It sounds like an LLVM bug. |
| bool AddressSanitizer::poisonStackInFunction(Module &M, Function &F) { |
| if (!ClStack) return false; |
| SmallVector<AllocaInst*, 16> AllocaVec; |
| SmallVector<Instruction*, 8> RetVec; |
| uint64_t TotalSize = 0; |
| |
| // Filter out Alloca instructions we want (and can) handle. |
| // Collect Ret instructions. |
| for (Function::iterator FI = F.begin(), FE = F.end(); |
| FI != FE; ++FI) { |
| BasicBlock &BB = *FI; |
| for (BasicBlock::iterator BI = BB.begin(), BE = BB.end(); |
| BI != BE; ++BI) { |
| if (isa<ReturnInst>(BI)) { |
| RetVec.push_back(BI); |
| continue; |
| } |
| |
| AllocaInst *AI = dyn_cast<AllocaInst>(BI); |
| if (!AI) continue; |
| if (AI->isArrayAllocation()) continue; |
| if (!AI->isStaticAlloca()) continue; |
| if (!AI->getAllocatedType()->isSized()) continue; |
| if (AI->getAlignment() > RedzoneSize) continue; |
| AllocaVec.push_back(AI); |
| uint64_t AlignedSize = getAlignedAllocaSize(AI); |
| TotalSize += AlignedSize; |
| } |
| } |
| |
| if (AllocaVec.empty()) return false; |
| |
| uint64_t LocalStackSize = TotalSize + (AllocaVec.size() + 1) * RedzoneSize; |
| |
| bool DoStackMalloc = ClUseAfterReturn |
| && LocalStackSize <= kMaxStackMallocSize; |
| |
| Instruction *InsBefore = AllocaVec[0]; |
| IRBuilder<> IRB(InsBefore); |
| |
| |
| Type *ByteArrayTy = ArrayType::get(IRB.getInt8Ty(), LocalStackSize); |
| AllocaInst *MyAlloca = |
| new AllocaInst(ByteArrayTy, "MyAlloca", InsBefore); |
| MyAlloca->setAlignment(RedzoneSize); |
| assert(MyAlloca->isStaticAlloca()); |
| Value *OrigStackBase = IRB.CreatePointerCast(MyAlloca, IntptrTy); |
| Value *LocalStackBase = OrigStackBase; |
| |
| if (DoStackMalloc) { |
| Value *AsanStackMallocFunc = M.getOrInsertFunction( |
| kAsanStackMallocName, IntptrTy, IntptrTy, IntptrTy, NULL); |
| LocalStackBase = IRB.CreateCall2(AsanStackMallocFunc, |
| ConstantInt::get(IntptrTy, LocalStackSize), OrigStackBase); |
| } |
| |
| // This string will be parsed by the run-time (DescribeStackAddress). |
| SmallString<2048> StackDescriptionStorage; |
| raw_svector_ostream StackDescription(StackDescriptionStorage); |
| StackDescription << F.getName() << " " << AllocaVec.size() << " "; |
| |
| uint64_t Pos = RedzoneSize; |
| // Replace Alloca instructions with base+offset. |
| for (size_t i = 0, n = AllocaVec.size(); i < n; i++) { |
| AllocaInst *AI = AllocaVec[i]; |
| uint64_t SizeInBytes = getAllocaSizeInBytes(AI); |
| StringRef Name = AI->getName(); |
| StackDescription << Pos << " " << SizeInBytes << " " |
| << Name.size() << " " << Name << " "; |
| uint64_t AlignedSize = getAlignedAllocaSize(AI); |
| assert((AlignedSize % RedzoneSize) == 0); |
| AI->replaceAllUsesWith( |
| IRB.CreateIntToPtr( |
| IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy, Pos)), |
| AI->getType())); |
| Pos += AlignedSize + RedzoneSize; |
| } |
| assert(Pos == LocalStackSize); |
| |
| // Write the Magic value and the frame description constant to the redzone. |
| Value *BasePlus0 = IRB.CreateIntToPtr(LocalStackBase, IntptrPtrTy); |
| IRB.CreateStore(ConstantInt::get(IntptrTy, kCurrentStackFrameMagic), |
| BasePlus0); |
| Value *BasePlus1 = IRB.CreateAdd(LocalStackBase, |
| ConstantInt::get(IntptrTy, LongSize/8)); |
| BasePlus1 = IRB.CreateIntToPtr(BasePlus1, IntptrPtrTy); |
| Value *Description = IRB.CreatePointerCast( |
| createPrivateGlobalForString(M, StackDescription.str()), |
| IntptrTy); |
| IRB.CreateStore(Description, BasePlus1); |
| |
| // Poison the stack redzones at the entry. |
| Value *ShadowBase = memToShadow(LocalStackBase, IRB); |
| PoisonStack(ArrayRef<AllocaInst*>(AllocaVec), IRB, ShadowBase, true); |
| |
| Value *AsanStackFreeFunc = NULL; |
| if (DoStackMalloc) { |
| AsanStackFreeFunc = M.getOrInsertFunction( |
| kAsanStackFreeName, IRB.getVoidTy(), |
| IntptrTy, IntptrTy, IntptrTy, NULL); |
| } |
| |
| // Unpoison the stack before all ret instructions. |
| for (size_t i = 0, n = RetVec.size(); i < n; i++) { |
| Instruction *Ret = RetVec[i]; |
| IRBuilder<> IRBRet(Ret); |
| |
| // Mark the current frame as retired. |
| IRBRet.CreateStore(ConstantInt::get(IntptrTy, kRetiredStackFrameMagic), |
| BasePlus0); |
| // Unpoison the stack. |
| PoisonStack(ArrayRef<AllocaInst*>(AllocaVec), IRBRet, ShadowBase, false); |
| |
| if (DoStackMalloc) { |
| IRBRet.CreateCall3(AsanStackFreeFunc, LocalStackBase, |
| ConstantInt::get(IntptrTy, LocalStackSize), |
| OrigStackBase); |
| } |
| } |
| |
| if (ClDebugStack) { |
| DEBUG(dbgs() << F); |
| } |
| |
| return true; |
| } |