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Diffstat (limited to 'contrib/llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp')
| -rw-r--r-- | contrib/llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp | 2021 |
1 files changed, 2021 insertions, 0 deletions
diff --git a/contrib/llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp b/contrib/llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp new file mode 100644 index 0000000..25f1f02 --- /dev/null +++ b/contrib/llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp @@ -0,0 +1,2021 @@ +//===-- 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 +// +//===----------------------------------------------------------------------===// + +#include "llvm/Transforms/Instrumentation.h" +#include "llvm/ADT/ArrayRef.h" +#include "llvm/ADT/DenseMap.h" +#include "llvm/ADT/DenseSet.h" +#include "llvm/ADT/DepthFirstIterator.h" +#include "llvm/ADT/SmallSet.h" +#include "llvm/ADT/SmallString.h" +#include "llvm/ADT/SmallVector.h" +#include "llvm/ADT/Statistic.h" +#include "llvm/ADT/StringExtras.h" +#include "llvm/ADT/Triple.h" +#include "llvm/IR/CallSite.h" +#include "llvm/IR/DIBuilder.h" +#include "llvm/IR/DataLayout.h" +#include "llvm/IR/Dominators.h" +#include "llvm/IR/Function.h" +#include "llvm/IR/IRBuilder.h" +#include "llvm/IR/InlineAsm.h" +#include "llvm/IR/InstVisitor.h" +#include "llvm/IR/IntrinsicInst.h" +#include "llvm/IR/LLVMContext.h" +#include "llvm/IR/MDBuilder.h" +#include "llvm/IR/Module.h" +#include "llvm/IR/Type.h" +#include "llvm/MC/MCSectionMachO.h" +#include "llvm/Support/CommandLine.h" +#include "llvm/Support/DataTypes.h" +#include "llvm/Support/Debug.h" +#include "llvm/Support/Endian.h" +#include "llvm/Support/SwapByteOrder.h" +#include "llvm/Transforms/Scalar.h" +#include "llvm/Transforms/Utils/ASanStackFrameLayout.h" +#include "llvm/Transforms/Utils/BasicBlockUtils.h" +#include "llvm/Transforms/Utils/Cloning.h" +#include "llvm/Transforms/Utils/Local.h" +#include "llvm/Transforms/Utils/ModuleUtils.h" +#include <algorithm> +#include <string> +#include <system_error> + +using namespace llvm; + +#define DEBUG_TYPE "asan" + +static const uint64_t kDefaultShadowScale = 3; +static const uint64_t kDefaultShadowOffset32 = 1ULL << 29; +static const uint64_t kIOSShadowOffset32 = 1ULL << 30; +static const uint64_t kDefaultShadowOffset64 = 1ULL << 44; +static const uint64_t kSmallX86_64ShadowOffset = 0x7FFF8000; // < 2G. +static const uint64_t kPPC64_ShadowOffset64 = 1ULL << 41; +static const uint64_t kMIPS32_ShadowOffset32 = 0x0aaa0000; +static const uint64_t kMIPS64_ShadowOffset64 = 1ULL << 36; +static const uint64_t kFreeBSD_ShadowOffset32 = 1ULL << 30; +static const uint64_t kFreeBSD_ShadowOffset64 = 1ULL << 46; +static const uint64_t kWindowsShadowOffset32 = 3ULL << 28; + +static const size_t kMinStackMallocSize = 1 << 6; // 64B +static const size_t kMaxStackMallocSize = 1 << 16; // 64K +static const uintptr_t kCurrentStackFrameMagic = 0x41B58AB3; +static const uintptr_t kRetiredStackFrameMagic = 0x45E0360E; + +static const char *const kAsanModuleCtorName = "asan.module_ctor"; +static const char *const kAsanModuleDtorName = "asan.module_dtor"; +static const uint64_t kAsanCtorAndDtorPriority = 1; +static const char *const kAsanReportErrorTemplate = "__asan_report_"; +static const char *const kAsanReportLoadN = "__asan_report_load_n"; +static const char *const kAsanReportStoreN = "__asan_report_store_n"; +static const char *const kAsanRegisterGlobalsName = "__asan_register_globals"; +static const char *const kAsanUnregisterGlobalsName = + "__asan_unregister_globals"; +static const char *const kAsanPoisonGlobalsName = "__asan_before_dynamic_init"; +static const char *const kAsanUnpoisonGlobalsName = "__asan_after_dynamic_init"; +static const char *const kAsanInitName = "__asan_init_v5"; +static const char *const kAsanPtrCmp = "__sanitizer_ptr_cmp"; +static const char *const kAsanPtrSub = "__sanitizer_ptr_sub"; +static const char *const kAsanHandleNoReturnName = "__asan_handle_no_return"; +static const int kMaxAsanStackMallocSizeClass = 10; +static const char *const kAsanStackMallocNameTemplate = "__asan_stack_malloc_"; +static const char *const kAsanStackFreeNameTemplate = "__asan_stack_free_"; +static const char *const kAsanGenPrefix = "__asan_gen_"; +static const char *const kSanCovGenPrefix = "__sancov_gen_"; +static const char *const kAsanPoisonStackMemoryName = + "__asan_poison_stack_memory"; +static const char *const kAsanUnpoisonStackMemoryName = + "__asan_unpoison_stack_memory"; + +static const char *const kAsanOptionDetectUAR = + "__asan_option_detect_stack_use_after_return"; + +#ifndef NDEBUG +static const int kAsanStackAfterReturnMagic = 0xf5; +#endif + +// Accesses sizes are powers of two: 1, 2, 4, 8, 16. +static const size_t kNumberOfAccessSizes = 5; + +static const unsigned kAllocaRzSize = 32; +static const unsigned kAsanAllocaLeftMagic = 0xcacacacaU; +static const unsigned kAsanAllocaRightMagic = 0xcbcbcbcbU; +static const unsigned kAsanAllocaPartialVal1 = 0xcbcbcb00U; +static const unsigned kAsanAllocaPartialVal2 = 0x000000cbU; + +// 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)); +static cl::opt<bool> ClInstrumentAtomics("asan-instrument-atomics", + cl::desc("instrument atomic instructions (rmw, cmpxchg)"), + cl::Hidden, cl::init(true)); +static cl::opt<bool> ClAlwaysSlowPath("asan-always-slow-path", + cl::desc("use instrumentation with slow path for all accesses"), + cl::Hidden, cl::init(false)); +// This flag limits the number of instructions to be instrumented +// in any given BB. Normally, this should be set to unlimited (INT_MAX), +// but due to http://llvm.org/bugs/show_bug.cgi?id=12652 we temporary +// set it to 10000. +static cl::opt<int> ClMaxInsnsToInstrumentPerBB("asan-max-ins-per-bb", + cl::init(10000), + cl::desc("maximal number of instructions to instrument in any given BB"), + cl::Hidden); +// 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)); +static cl::opt<bool> ClUseAfterReturn("asan-use-after-return", + cl::desc("Check return-after-free"), cl::Hidden, cl::init(true)); +// 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> ClInitializers("asan-initialization-order", + cl::desc("Handle C++ initializer order"), cl::Hidden, cl::init(true)); +static cl::opt<bool> ClInvalidPointerPairs("asan-detect-invalid-pointer-pair", + cl::desc("Instrument <, <=, >, >=, - with pointer operands"), + cl::Hidden, cl::init(false)); +static cl::opt<unsigned> ClRealignStack("asan-realign-stack", + cl::desc("Realign stack to the value of this flag (power of two)"), + cl::Hidden, cl::init(32)); +static cl::opt<int> ClInstrumentationWithCallsThreshold( + "asan-instrumentation-with-call-threshold", + cl::desc("If the function being instrumented contains more than " + "this number of memory accesses, use callbacks instead of " + "inline checks (-1 means never use callbacks)."), + cl::Hidden, cl::init(7000)); +static cl::opt<std::string> ClMemoryAccessCallbackPrefix( + "asan-memory-access-callback-prefix", + cl::desc("Prefix for memory access callbacks"), cl::Hidden, + cl::init("__asan_")); +static cl::opt<bool> ClInstrumentAllocas("asan-instrument-allocas", + cl::desc("instrument dynamic allocas"), cl::Hidden, cl::init(false)); + +// 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)); + +// 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)); + +static cl::opt<bool> ClCheckLifetime("asan-check-lifetime", + cl::desc("Use llvm.lifetime intrinsics to insert extra checks"), + cl::Hidden, cl::init(false)); + +static cl::opt<bool> ClDynamicAllocaStack( + "asan-stack-dynamic-alloca", + cl::desc("Use dynamic alloca to represent stack variables"), cl::Hidden, + cl::init(false)); + +// 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)); + +STATISTIC(NumInstrumentedReads, "Number of instrumented reads"); +STATISTIC(NumInstrumentedWrites, "Number of instrumented writes"); +STATISTIC(NumInstrumentedDynamicAllocas, + "Number of instrumented dynamic allocas"); +STATISTIC(NumOptimizedAccessesToGlobalArray, + "Number of optimized accesses to global arrays"); +STATISTIC(NumOptimizedAccessesToGlobalVar, + "Number of optimized accesses to global vars"); + +namespace { +/// Frontend-provided metadata for source location. +struct LocationMetadata { + StringRef Filename; + int LineNo; + int ColumnNo; + + LocationMetadata() : Filename(), LineNo(0), ColumnNo(0) {} + + bool empty() const { return Filename.empty(); } + + void parse(MDNode *MDN) { + assert(MDN->getNumOperands() == 3); + MDString *MDFilename = cast<MDString>(MDN->getOperand(0)); + Filename = MDFilename->getString(); + LineNo = + mdconst::extract<ConstantInt>(MDN->getOperand(1))->getLimitedValue(); + ColumnNo = + mdconst::extract<ConstantInt>(MDN->getOperand(2))->getLimitedValue(); + } +}; + +/// Frontend-provided metadata for global variables. +class GlobalsMetadata { + public: + struct Entry { + Entry() + : SourceLoc(), Name(), IsDynInit(false), + IsBlacklisted(false) {} + LocationMetadata SourceLoc; + StringRef Name; + bool IsDynInit; + bool IsBlacklisted; + }; + + GlobalsMetadata() : inited_(false) {} + + void init(Module& M) { + assert(!inited_); + inited_ = true; + NamedMDNode *Globals = M.getNamedMetadata("llvm.asan.globals"); + if (!Globals) + return; + for (auto MDN : Globals->operands()) { + // Metadata node contains the global and the fields of "Entry". + assert(MDN->getNumOperands() == 5); + auto *GV = mdconst::extract_or_null<GlobalVariable>(MDN->getOperand(0)); + // The optimizer may optimize away a global entirely. + if (!GV) + continue; + // We can already have an entry for GV if it was merged with another + // global. + Entry &E = Entries[GV]; + if (auto *Loc = cast_or_null<MDNode>(MDN->getOperand(1))) + E.SourceLoc.parse(Loc); + if (auto *Name = cast_or_null<MDString>(MDN->getOperand(2))) + E.Name = Name->getString(); + ConstantInt *IsDynInit = + mdconst::extract<ConstantInt>(MDN->getOperand(3)); + E.IsDynInit |= IsDynInit->isOne(); + ConstantInt *IsBlacklisted = + mdconst::extract<ConstantInt>(MDN->getOperand(4)); + E.IsBlacklisted |= IsBlacklisted->isOne(); + } + } + + /// Returns metadata entry for a given global. + Entry get(GlobalVariable *G) const { + auto Pos = Entries.find(G); + return (Pos != Entries.end()) ? Pos->second : Entry(); + } + + private: + bool inited_; + DenseMap<GlobalVariable*, Entry> Entries; +}; + +/// This struct defines the shadow mapping using the rule: +/// shadow = (mem >> Scale) ADD-or-OR Offset. +struct ShadowMapping { + int Scale; + uint64_t Offset; + bool OrShadowOffset; +}; + +static ShadowMapping getShadowMapping(Triple &TargetTriple, int LongSize) { + bool IsAndroid = TargetTriple.getEnvironment() == llvm::Triple::Android; + bool IsIOS = TargetTriple.isiOS(); + bool IsFreeBSD = TargetTriple.isOSFreeBSD(); + bool IsLinux = TargetTriple.isOSLinux(); + bool IsPPC64 = TargetTriple.getArch() == llvm::Triple::ppc64 || + TargetTriple.getArch() == llvm::Triple::ppc64le; + bool IsX86_64 = TargetTriple.getArch() == llvm::Triple::x86_64; + bool IsMIPS32 = TargetTriple.getArch() == llvm::Triple::mips || + TargetTriple.getArch() == llvm::Triple::mipsel; + bool IsMIPS64 = TargetTriple.getArch() == llvm::Triple::mips64 || + TargetTriple.getArch() == llvm::Triple::mips64el; + bool IsWindows = TargetTriple.isOSWindows(); + + ShadowMapping Mapping; + + if (LongSize == 32) { + if (IsAndroid) + Mapping.Offset = 0; + else if (IsMIPS32) + Mapping.Offset = kMIPS32_ShadowOffset32; + else if (IsFreeBSD) + Mapping.Offset = kFreeBSD_ShadowOffset32; + else if (IsIOS) + Mapping.Offset = kIOSShadowOffset32; + else if (IsWindows) + Mapping.Offset = kWindowsShadowOffset32; + else + Mapping.Offset = kDefaultShadowOffset32; + } else { // LongSize == 64 + if (IsPPC64) + Mapping.Offset = kPPC64_ShadowOffset64; + else if (IsFreeBSD) + Mapping.Offset = kFreeBSD_ShadowOffset64; + else if (IsLinux && IsX86_64) + Mapping.Offset = kSmallX86_64ShadowOffset; + else if (IsMIPS64) + Mapping.Offset = kMIPS64_ShadowOffset64; + else + Mapping.Offset = kDefaultShadowOffset64; + } + + Mapping.Scale = kDefaultShadowScale; + if (ClMappingScale) { + Mapping.Scale = ClMappingScale; + } + + // OR-ing shadow offset if more efficient (at least on x86) if the offset + // is a power of two, but on ppc64 we have to use add since the shadow + // offset is not necessary 1/8-th of the address space. + Mapping.OrShadowOffset = !IsPPC64 && !(Mapping.Offset & (Mapping.Offset - 1)); + + return Mapping; +} + +static size_t RedzoneSizeForScale(int MappingScale) { + // 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. + return std::max(32U, 1U << MappingScale); +} + +/// AddressSanitizer: instrument the code in module to find memory bugs. +struct AddressSanitizer : public FunctionPass { + AddressSanitizer() : FunctionPass(ID) { + initializeAddressSanitizerPass(*PassRegistry::getPassRegistry()); + } + const char *getPassName() const override { + return "AddressSanitizerFunctionPass"; + } + void getAnalysisUsage(AnalysisUsage &AU) const override { + AU.addRequired<DominatorTreeWrapperPass>(); + } + void instrumentMop(Instruction *I, bool UseCalls); + void instrumentPointerComparisonOrSubtraction(Instruction *I); + void instrumentAddress(Instruction *OrigIns, Instruction *InsertBefore, + Value *Addr, uint32_t TypeSize, bool IsWrite, + Value *SizeArgument, bool UseCalls); + Value *createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong, + Value *ShadowValue, uint32_t TypeSize); + Instruction *generateCrashCode(Instruction *InsertBefore, Value *Addr, + bool IsWrite, size_t AccessSizeIndex, + Value *SizeArgument); + void instrumentMemIntrinsic(MemIntrinsic *MI); + Value *memToShadow(Value *Shadow, IRBuilder<> &IRB); + bool runOnFunction(Function &F) override; + bool maybeInsertAsanInitAtFunctionEntry(Function &F); + bool doInitialization(Module &M) override; + static char ID; // Pass identification, replacement for typeid + + DominatorTree &getDominatorTree() const { return *DT; } + + private: + void initializeCallbacks(Module &M); + + bool LooksLikeCodeInBug11395(Instruction *I); + bool GlobalIsLinkerInitialized(GlobalVariable *G); + + LLVMContext *C; + const DataLayout *DL; + Triple TargetTriple; + int LongSize; + Type *IntptrTy; + ShadowMapping Mapping; + DominatorTree *DT; + Function *AsanCtorFunction; + Function *AsanInitFunction; + Function *AsanHandleNoReturnFunc; + Function *AsanPtrCmpFunction, *AsanPtrSubFunction; + // This array is indexed by AccessIsWrite and log2(AccessSize). + Function *AsanErrorCallback[2][kNumberOfAccessSizes]; + Function *AsanMemoryAccessCallback[2][kNumberOfAccessSizes]; + // This array is indexed by AccessIsWrite. + Function *AsanErrorCallbackSized[2], + *AsanMemoryAccessCallbackSized[2]; + Function *AsanMemmove, *AsanMemcpy, *AsanMemset; + InlineAsm *EmptyAsm; + GlobalsMetadata GlobalsMD; + + friend struct FunctionStackPoisoner; +}; + +class AddressSanitizerModule : public ModulePass { + public: + AddressSanitizerModule() : ModulePass(ID) {} + bool runOnModule(Module &M) override; + static char ID; // Pass identification, replacement for typeid + const char *getPassName() const override { + return "AddressSanitizerModule"; + } + + private: + void initializeCallbacks(Module &M); + + bool InstrumentGlobals(IRBuilder<> &IRB, Module &M); + bool ShouldInstrumentGlobal(GlobalVariable *G); + void poisonOneInitializer(Function &GlobalInit, GlobalValue *ModuleName); + void createInitializerPoisonCalls(Module &M, GlobalValue *ModuleName); + size_t MinRedzoneSizeForGlobal() const { + return RedzoneSizeForScale(Mapping.Scale); + } + + GlobalsMetadata GlobalsMD; + Type *IntptrTy; + LLVMContext *C; + const DataLayout *DL; + Triple TargetTriple; + ShadowMapping Mapping; + Function *AsanPoisonGlobals; + Function *AsanUnpoisonGlobals; + Function *AsanRegisterGlobals; + Function *AsanUnregisterGlobals; +}; + +// 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. +struct FunctionStackPoisoner : public InstVisitor<FunctionStackPoisoner> { + Function &F; + AddressSanitizer &ASan; + DIBuilder DIB; + LLVMContext *C; + Type *IntptrTy; + Type *IntptrPtrTy; + ShadowMapping Mapping; + + SmallVector<AllocaInst*, 16> AllocaVec; + SmallVector<Instruction*, 8> RetVec; + unsigned StackAlignment; + + Function *AsanStackMallocFunc[kMaxAsanStackMallocSizeClass + 1], + *AsanStackFreeFunc[kMaxAsanStackMallocSizeClass + 1]; + Function *AsanPoisonStackMemoryFunc, *AsanUnpoisonStackMemoryFunc; + + // Stores a place and arguments of poisoning/unpoisoning call for alloca. + struct AllocaPoisonCall { + IntrinsicInst *InsBefore; + AllocaInst *AI; + uint64_t Size; + bool DoPoison; + }; + SmallVector<AllocaPoisonCall, 8> AllocaPoisonCallVec; + + // Stores left and right redzone shadow addresses for dynamic alloca + // and pointer to alloca instruction itself. + // LeftRzAddr is a shadow address for alloca left redzone. + // RightRzAddr is a shadow address for alloca right redzone. + struct DynamicAllocaCall { + AllocaInst *AI; + Value *LeftRzAddr; + Value *RightRzAddr; + bool Poison; + explicit DynamicAllocaCall(AllocaInst *AI, + Value *LeftRzAddr = nullptr, + Value *RightRzAddr = nullptr) + : AI(AI), LeftRzAddr(LeftRzAddr), RightRzAddr(RightRzAddr), Poison(true) + {} + }; + SmallVector<DynamicAllocaCall, 1> DynamicAllocaVec; + + // Maps Value to an AllocaInst from which the Value is originated. + typedef DenseMap<Value*, AllocaInst*> AllocaForValueMapTy; + AllocaForValueMapTy AllocaForValue; + + bool HasNonEmptyInlineAsm; + std::unique_ptr<CallInst> EmptyInlineAsm; + + FunctionStackPoisoner(Function &F, AddressSanitizer &ASan) + : F(F), ASan(ASan), DIB(*F.getParent(), /*AllowUnresolved*/ false), + C(ASan.C), IntptrTy(ASan.IntptrTy), + IntptrPtrTy(PointerType::get(IntptrTy, 0)), Mapping(ASan.Mapping), + StackAlignment(1 << Mapping.Scale), HasNonEmptyInlineAsm(false), + EmptyInlineAsm(CallInst::Create(ASan.EmptyAsm)) {} + + bool runOnFunction() { + if (!ClStack) return false; + // Collect alloca, ret, lifetime instructions etc. + for (BasicBlock *BB : depth_first(&F.getEntryBlock())) + visit(*BB); + + if (AllocaVec.empty() && DynamicAllocaVec.empty()) return false; + + initializeCallbacks(*F.getParent()); + + poisonStack(); + + if (ClDebugStack) { + DEBUG(dbgs() << F); + } + return true; + } + + // Finds all Alloca instructions and puts + // poisoned red zones around all of them. + // Then unpoison everything back before the function returns. + void poisonStack(); + + // ----------------------- Visitors. + /// \brief Collect all Ret instructions. + void visitReturnInst(ReturnInst &RI) { + RetVec.push_back(&RI); + } + + // Unpoison dynamic allocas redzones. + void unpoisonDynamicAlloca(DynamicAllocaCall &AllocaCall) { + if (!AllocaCall.Poison) + return; + for (auto Ret : RetVec) { + IRBuilder<> IRBRet(Ret); + PointerType *Int32PtrTy = PointerType::getUnqual(IRBRet.getInt32Ty()); + Value *Zero = Constant::getNullValue(IRBRet.getInt32Ty()); + Value *PartialRzAddr = IRBRet.CreateSub(AllocaCall.RightRzAddr, + ConstantInt::get(IntptrTy, 4)); + IRBRet.CreateStore(Zero, IRBRet.CreateIntToPtr(AllocaCall.LeftRzAddr, + Int32PtrTy)); + IRBRet.CreateStore(Zero, IRBRet.CreateIntToPtr(PartialRzAddr, + Int32PtrTy)); + IRBRet.CreateStore(Zero, IRBRet.CreateIntToPtr(AllocaCall.RightRzAddr, + Int32PtrTy)); + } + } + + // Right shift for BigEndian and left shift for LittleEndian. + Value *shiftAllocaMagic(Value *Val, IRBuilder<> &IRB, Value *Shift) { + return ASan.DL->isLittleEndian() ? IRB.CreateShl(Val, Shift) + : IRB.CreateLShr(Val, Shift); + } + + // Compute PartialRzMagic for dynamic alloca call. Since we don't know the + // size of requested memory until runtime, we should compute it dynamically. + // If PartialSize is 0, PartialRzMagic would contain kAsanAllocaRightMagic, + // otherwise it would contain the value that we will use to poison the + // partial redzone for alloca call. + Value *computePartialRzMagic(Value *PartialSize, IRBuilder<> &IRB); + + // Deploy and poison redzones around dynamic alloca call. To do this, we + // should replace this call with another one with changed parameters and + // replace all its uses with new address, so + // addr = alloca type, old_size, align + // is replaced by + // new_size = (old_size + additional_size) * sizeof(type) + // tmp = alloca i8, new_size, max(align, 32) + // addr = tmp + 32 (first 32 bytes are for the left redzone). + // Additional_size is added to make new memory allocation contain not only + // requested memory, but also left, partial and right redzones. + // After that, we should poison redzones: + // (1) Left redzone with kAsanAllocaLeftMagic. + // (2) Partial redzone with the value, computed in runtime by + // computePartialRzMagic function. + // (3) Right redzone with kAsanAllocaRightMagic. + void handleDynamicAllocaCall(DynamicAllocaCall &AllocaCall); + + /// \brief Collect Alloca instructions we want (and can) handle. + void visitAllocaInst(AllocaInst &AI) { + if (!isInterestingAlloca(AI)) return; + + StackAlignment = std::max(StackAlignment, AI.getAlignment()); + if (isDynamicAlloca(AI)) + DynamicAllocaVec.push_back(DynamicAllocaCall(&AI)); + else + AllocaVec.push_back(&AI); + } + + /// \brief Collect lifetime intrinsic calls to check for use-after-scope + /// errors. + void visitIntrinsicInst(IntrinsicInst &II) { + if (!ClCheckLifetime) return; + Intrinsic::ID ID = II.getIntrinsicID(); + if (ID != Intrinsic::lifetime_start && + ID != Intrinsic::lifetime_end) + return; + // Found lifetime intrinsic, add ASan instrumentation if necessary. + ConstantInt *Size = dyn_cast<ConstantInt>(II.getArgOperand(0)); + // If size argument is undefined, don't do anything. + if (Size->isMinusOne()) return; + // Check that size doesn't saturate uint64_t and can + // be stored in IntptrTy. + const uint64_t SizeValue = Size->getValue().getLimitedValue(); + if (SizeValue == ~0ULL || + !ConstantInt::isValueValidForType(IntptrTy, SizeValue)) + return; + // Find alloca instruction that corresponds to llvm.lifetime argument. + AllocaInst *AI = findAllocaForValue(II.getArgOperand(1)); + if (!AI) return; + bool DoPoison = (ID == Intrinsic::lifetime_end); + AllocaPoisonCall APC = {&II, AI, SizeValue, DoPoison}; + AllocaPoisonCallVec.push_back(APC); + } + + void visitCallInst(CallInst &CI) { + HasNonEmptyInlineAsm |= + CI.isInlineAsm() && !CI.isIdenticalTo(EmptyInlineAsm.get()); + } + + // ---------------------- Helpers. + void initializeCallbacks(Module &M); + + bool doesDominateAllExits(const Instruction *I) const { + for (auto Ret : RetVec) { + if (!ASan.getDominatorTree().dominates(I, Ret)) + return false; + } + return true; + } + + bool isDynamicAlloca(AllocaInst &AI) const { + return AI.isArrayAllocation() || !AI.isStaticAlloca(); + } + + // Check if we want (and can) handle this alloca. + bool isInterestingAlloca(AllocaInst &AI) const { + return (AI.getAllocatedType()->isSized() && + // alloca() may be called with 0 size, ignore it. + getAllocaSizeInBytes(&AI) > 0); + } + + uint64_t getAllocaSizeInBytes(AllocaInst *AI) const { + Type *Ty = AI->getAllocatedType(); + uint64_t SizeInBytes = ASan.DL->getTypeAllocSize(Ty); + return SizeInBytes; + } + /// Finds alloca where the value comes from. + AllocaInst *findAllocaForValue(Value *V); + void poisonRedZones(ArrayRef<uint8_t> ShadowBytes, IRBuilder<> &IRB, + Value *ShadowBase, bool DoPoison); + void poisonAlloca(Value *V, uint64_t Size, IRBuilder<> &IRB, bool DoPoison); + + void SetShadowToStackAfterReturnInlined(IRBuilder<> &IRB, Value *ShadowBase, + int Size); + Value *createAllocaForLayout(IRBuilder<> &IRB, const ASanStackFrameLayout &L, + bool Dynamic); + PHINode *createPHI(IRBuilder<> &IRB, Value *Cond, Value *ValueIfTrue, + Instruction *ThenTerm, Value *ValueIfFalse); +}; + +} // namespace + +char AddressSanitizer::ID = 0; +INITIALIZE_PASS_BEGIN(AddressSanitizer, "asan", + "AddressSanitizer: detects use-after-free and out-of-bounds bugs.", + false, false) +INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass) +INITIALIZE_PASS_END(AddressSanitizer, "asan", + "AddressSanitizer: detects use-after-free and out-of-bounds bugs.", + false, false) +FunctionPass *llvm::createAddressSanitizerFunctionPass() { + return new AddressSanitizer(); +} + +char AddressSanitizerModule::ID = 0; +INITIALIZE_PASS(AddressSanitizerModule, "asan-module", + "AddressSanitizer: detects use-after-free and out-of-bounds bugs." + "ModulePass", false, false) +ModulePass *llvm::createAddressSanitizerModulePass() { + return new AddressSanitizerModule(); +} + +static size_t TypeSizeToSizeIndex(uint32_t TypeSize) { + size_t Res = countTrailingZeros(TypeSize / 8); + assert(Res < kNumberOfAccessSizes); + return Res; +} + +// \brief Create a constant for Str so that we can pass it to the run-time lib. +static GlobalVariable *createPrivateGlobalForString( + Module &M, StringRef Str, bool AllowMerging) { + Constant *StrConst = ConstantDataArray::getString(M.getContext(), Str); + // We use private linkage for module-local strings. If they can be merged + // with another one, we set the unnamed_addr attribute. + GlobalVariable *GV = + new GlobalVariable(M, StrConst->getType(), true, + GlobalValue::PrivateLinkage, StrConst, kAsanGenPrefix); + if (AllowMerging) + GV->setUnnamedAddr(true); + GV->setAlignment(1); // Strings may not be merged w/o setting align 1. + return GV; +} + +/// \brief Create a global describing a source location. +static GlobalVariable *createPrivateGlobalForSourceLoc(Module &M, + LocationMetadata MD) { + Constant *LocData[] = { + createPrivateGlobalForString(M, MD.Filename, true), + ConstantInt::get(Type::getInt32Ty(M.getContext()), MD.LineNo), + ConstantInt::get(Type::getInt32Ty(M.getContext()), MD.ColumnNo), + }; + auto LocStruct = ConstantStruct::getAnon(LocData); + auto GV = new GlobalVariable(M, LocStruct->getType(), true, + GlobalValue::PrivateLinkage, LocStruct, + kAsanGenPrefix); + GV->setUnnamedAddr(true); + return GV; +} + +static bool GlobalWasGeneratedByAsan(GlobalVariable *G) { + return G->getName().find(kAsanGenPrefix) == 0 || + G->getName().find(kSanCovGenPrefix) == 0; +} + +Value *AddressSanitizer::memToShadow(Value *Shadow, IRBuilder<> &IRB) { + // Shadow >> scale + Shadow = IRB.CreateLShr(Shadow, Mapping.Scale); + if (Mapping.Offset == 0) + return Shadow; + // (Shadow >> scale) | offset + if (Mapping.OrShadowOffset) + return IRB.CreateOr(Shadow, ConstantInt::get(IntptrTy, Mapping.Offset)); + else + return IRB.CreateAdd(Shadow, ConstantInt::get(IntptrTy, Mapping.Offset)); +} + +// Instrument memset/memmove/memcpy +void AddressSanitizer::instrumentMemIntrinsic(MemIntrinsic *MI) { + IRBuilder<> IRB(MI); + if (isa<MemTransferInst>(MI)) { + IRB.CreateCall3( + isa<MemMoveInst>(MI) ? AsanMemmove : AsanMemcpy, + IRB.CreatePointerCast(MI->getOperand(0), IRB.getInt8PtrTy()), + IRB.CreatePointerCast(MI->getOperand(1), IRB.getInt8PtrTy()), + IRB.CreateIntCast(MI->getOperand(2), IntptrTy, false)); + } else if (isa<MemSetInst>(MI)) { + IRB.CreateCall3( + AsanMemset, + IRB.CreatePointerCast(MI->getOperand(0), IRB.getInt8PtrTy()), + IRB.CreateIntCast(MI->getOperand(1), IRB.getInt32Ty(), false), + IRB.CreateIntCast(MI->getOperand(2), IntptrTy, false)); + } + MI->eraseFromParent(); +} + +// If I is an interesting memory access, return the PointerOperand +// and set IsWrite/Alignment. Otherwise return nullptr. +static Value *isInterestingMemoryAccess(Instruction *I, bool *IsWrite, + unsigned *Alignment) { + // Skip memory accesses inserted by another instrumentation. + if (I->getMetadata("nosanitize")) + return nullptr; + if (LoadInst *LI = dyn_cast<LoadInst>(I)) { + if (!ClInstrumentReads) return nullptr; + *IsWrite = false; + *Alignment = LI->getAlignment(); + return LI->getPointerOperand(); + } + if (StoreInst *SI = dyn_cast<StoreInst>(I)) { + if (!ClInstrumentWrites) return nullptr; + *IsWrite = true; + *Alignment = SI->getAlignment(); + return SI->getPointerOperand(); + } + if (AtomicRMWInst *RMW = dyn_cast<AtomicRMWInst>(I)) { + if (!ClInstrumentAtomics) return nullptr; + *IsWrite = true; + *Alignment = 0; + return RMW->getPointerOperand(); + } + if (AtomicCmpXchgInst *XCHG = dyn_cast<AtomicCmpXchgInst>(I)) { + if (!ClInstrumentAtomics) return nullptr; + *IsWrite = true; + *Alignment = 0; + return XCHG->getPointerOperand(); + } + return nullptr; +} + +static bool isPointerOperand(Value *V) { + return V->getType()->isPointerTy() || isa<PtrToIntInst>(V); +} + +// This is a rough heuristic; it may cause both false positives and +// false negatives. The proper implementation requires cooperation with +// the frontend. +static bool isInterestingPointerComparisonOrSubtraction(Instruction *I) { + if (ICmpInst *Cmp = dyn_cast<ICmpInst>(I)) { + if (!Cmp->isRelational()) + return false; + } else if (BinaryOperator *BO = dyn_cast<BinaryOperator>(I)) { + if (BO->getOpcode() != Instruction::Sub) + return false; + } else { + return false; + } + if (!isPointerOperand(I->getOperand(0)) || + !isPointerOperand(I->getOperand(1))) + return false; + return true; +} + +bool AddressSanitizer::GlobalIsLinkerInitialized(GlobalVariable *G) { + // If a global variable does not have dynamic initialization we don't + // have to instrument it. However, if a global does not have initializer + // at all, we assume it has dynamic initializer (in other TU). + return G->hasInitializer() && !GlobalsMD.get(G).IsDynInit; +} + +void +AddressSanitizer::instrumentPointerComparisonOrSubtraction(Instruction *I) { + IRBuilder<> IRB(I); + Function *F = isa<ICmpInst>(I) ? AsanPtrCmpFunction : AsanPtrSubFunction; + Value *Param[2] = {I->getOperand(0), I->getOperand(1)}; + for (int i = 0; i < 2; i++) { + if (Param[i]->getType()->isPointerTy()) + Param[i] = IRB.CreatePointerCast(Param[i], IntptrTy); + } + IRB.CreateCall2(F, Param[0], Param[1]); +} + +void AddressSanitizer::instrumentMop(Instruction *I, bool UseCalls) { + bool IsWrite = false; + unsigned Alignment = 0; + Value *Addr = isInterestingMemoryAccess(I, &IsWrite, &Alignment); + assert(Addr); + if (ClOpt && ClOptGlobals) { + if (GlobalVariable *G = dyn_cast<GlobalVariable>(Addr)) { + // If initialization order checking is disabled, a simple access to a + // dynamically initialized global is always valid. + if (!ClInitializers || GlobalIsLinkerInitialized(G)) { + NumOptimizedAccessesToGlobalVar++; + return; + } + } + ConstantExpr *CE = dyn_cast<ConstantExpr>(Addr); + if (CE && CE->isGEPWithNoNotionalOverIndexing()) { + if (GlobalVariable *G = dyn_cast<GlobalVariable>(CE->getOperand(0))) { + if (CE->getOperand(1)->isNullValue() && GlobalIsLinkerInitialized(G)) { + NumOptimizedAccessesToGlobalArray++; + return; + } + } + } + } + + Type *OrigPtrTy = Addr->getType(); + Type *OrigTy = cast<PointerType>(OrigPtrTy)->getElementType(); + + assert(OrigTy->isSized()); + uint32_t TypeSize = DL->getTypeStoreSizeInBits(OrigTy); + + assert((TypeSize % 8) == 0); + + if (IsWrite) + NumInstrumentedWrites++; + else + NumInstrumentedReads++; + + unsigned Granularity = 1 << Mapping.Scale; + // Instrument a 1-, 2-, 4-, 8-, or 16- byte access with one check + // if the data is properly aligned. + if ((TypeSize == 8 || TypeSize == 16 || TypeSize == 32 || TypeSize == 64 || + TypeSize == 128) && + (Alignment >= Granularity || Alignment == 0 || Alignment >= TypeSize / 8)) + return instrumentAddress(I, I, Addr, TypeSize, IsWrite, nullptr, UseCalls); + // Instrument unusual size or unusual alignment. + // We can not do it with a single check, so we do 1-byte check for the first + // and the last bytes. We call __asan_report_*_n(addr, real_size) to be able + // to report the actual access size. + IRBuilder<> IRB(I); + Value *Size = ConstantInt::get(IntptrTy, TypeSize / 8); + Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy); + if (UseCalls) { + IRB.CreateCall2(AsanMemoryAccessCallbackSized[IsWrite], AddrLong, Size); + } else { + Value *LastByte = IRB.CreateIntToPtr( + IRB.CreateAdd(AddrLong, ConstantInt::get(IntptrTy, TypeSize / 8 - 1)), + OrigPtrTy); + instrumentAddress(I, I, Addr, 8, IsWrite, Size, false); + instrumentAddress(I, I, LastByte, 8, IsWrite, Size, false); + } +} + +// Validate the result of Module::getOrInsertFunction called for an interface +// function of AddressSanitizer. If the instrumented module defines a function +// with the same name, their prototypes must match, otherwise +// getOrInsertFunction returns a bitcast. +static Function *checkInterfaceFunction(Constant *FuncOrBitcast) { + if (isa<Function>(FuncOrBitcast)) return cast<Function>(FuncOrBitcast); + FuncOrBitcast->dump(); + report_fatal_error("trying to redefine an AddressSanitizer " + "interface function"); +} + +Instruction *AddressSanitizer::generateCrashCode( + Instruction *InsertBefore, Value *Addr, + bool IsWrite, size_t AccessSizeIndex, Value *SizeArgument) { + IRBuilder<> IRB(InsertBefore); + CallInst *Call = SizeArgument + ? IRB.CreateCall2(AsanErrorCallbackSized[IsWrite], Addr, SizeArgument) + : IRB.CreateCall(AsanErrorCallback[IsWrite][AccessSizeIndex], Addr); + + // We don't do Call->setDoesNotReturn() because the BB already has + // UnreachableInst at the end. + // This EmptyAsm is required to avoid callback merge. + IRB.CreateCall(EmptyAsm); + return Call; +} + +Value *AddressSanitizer::createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong, + Value *ShadowValue, + uint32_t TypeSize) { + size_t Granularity = 1 << Mapping.Scale; + // Addr & (Granularity - 1) + Value *LastAccessedByte = IRB.CreateAnd( + AddrLong, ConstantInt::get(IntptrTy, Granularity - 1)); + // (Addr & (Granularity - 1)) + size - 1 + if (TypeSize / 8 > 1) + LastAccessedByte = IRB.CreateAdd( + LastAccessedByte, ConstantInt::get(IntptrTy, TypeSize / 8 - 1)); + // (uint8_t) ((Addr & (Granularity-1)) + size - 1) + LastAccessedByte = IRB.CreateIntCast( + LastAccessedByte, ShadowValue->getType(), false); + // ((uint8_t) ((Addr & (Granularity-1)) + size - 1)) >= ShadowValue + return IRB.CreateICmpSGE(LastAccessedByte, ShadowValue); +} + +void AddressSanitizer::instrumentAddress(Instruction *OrigIns, + Instruction *InsertBefore, Value *Addr, + uint32_t TypeSize, bool IsWrite, + Value *SizeArgument, bool UseCalls) { + IRBuilder<> IRB(InsertBefore); + Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy); + size_t AccessSizeIndex = TypeSizeToSizeIndex(TypeSize); + + if (UseCalls) { + IRB.CreateCall(AsanMemoryAccessCallback[IsWrite][AccessSizeIndex], + AddrLong); + return; + } + + Type *ShadowTy = IntegerType::get( + *C, std::max(8U, TypeSize >> Mapping.Scale)); + 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); + size_t Granularity = 1 << Mapping.Scale; + TerminatorInst *CrashTerm = nullptr; + + if (ClAlwaysSlowPath || (TypeSize < 8 * Granularity)) { + // We use branch weights for the slow path check, to indicate that the slow + // path is rarely taken. This seems to be the case for SPEC benchmarks. + TerminatorInst *CheckTerm = + SplitBlockAndInsertIfThen(Cmp, InsertBefore, false, + MDBuilder(*C).createBranchWeights(1, 100000)); + assert(dyn_cast<BranchInst>(CheckTerm)->isUnconditional()); + BasicBlock *NextBB = CheckTerm->getSuccessor(0); + IRB.SetInsertPoint(CheckTerm); + Value *Cmp2 = createSlowPathCmp(IRB, AddrLong, ShadowValue, TypeSize); + BasicBlock *CrashBlock = + BasicBlock::Create(*C, "", NextBB->getParent(), NextBB); + CrashTerm = new UnreachableInst(*C, CrashBlock); + BranchInst *NewTerm = BranchInst::Create(CrashBlock, NextBB, Cmp2); + ReplaceInstWithInst(CheckTerm, NewTerm); + } else { + CrashTerm = SplitBlockAndInsertIfThen(Cmp, InsertBefore, true); + } + + Instruction *Crash = generateCrashCode( + CrashTerm, AddrLong, IsWrite, AccessSizeIndex, SizeArgument); + Crash->setDebugLoc(OrigIns->getDebugLoc()); +} + +void AddressSanitizerModule::poisonOneInitializer(Function &GlobalInit, + GlobalValue *ModuleName) { + // Set up the arguments to our poison/unpoison functions. + IRBuilder<> IRB(GlobalInit.begin()->getFirstInsertionPt()); + + // Add a call to poison all external globals before the given function starts. + Value *ModuleNameAddr = ConstantExpr::getPointerCast(ModuleName, IntptrTy); + IRB.CreateCall(AsanPoisonGlobals, ModuleNameAddr); + + // Add calls to unpoison all globals before each return instruction. + for (auto &BB : GlobalInit.getBasicBlockList()) + if (ReturnInst *RI = dyn_cast<ReturnInst>(BB.getTerminator())) + CallInst::Create(AsanUnpoisonGlobals, "", RI); +} + +void AddressSanitizerModule::createInitializerPoisonCalls( + Module &M, GlobalValue *ModuleName) { + GlobalVariable *GV = M.getGlobalVariable("llvm.global_ctors"); + + ConstantArray *CA = cast<ConstantArray>(GV->getInitializer()); + for (Use &OP : CA->operands()) { + if (isa<ConstantAggregateZero>(OP)) + continue; + ConstantStruct *CS = cast<ConstantStruct>(OP); + + // Must have a function or null ptr. + if (Function* F = dyn_cast<Function>(CS->getOperand(1))) { + if (F->getName() == kAsanModuleCtorName) continue; + ConstantInt *Priority = dyn_cast<ConstantInt>(CS->getOperand(0)); + // Don't instrument CTORs that will run before asan.module_ctor. + if (Priority->getLimitedValue() <= kAsanCtorAndDtorPriority) continue; + poisonOneInitializer(*F, ModuleName); + } + } +} + +bool AddressSanitizerModule::ShouldInstrumentGlobal(GlobalVariable *G) { + Type *Ty = cast<PointerType>(G->getType())->getElementType(); + DEBUG(dbgs() << "GLOBAL: " << *G << "\n"); + + if (GlobalsMD.get(G).IsBlacklisted) return false; + if (!Ty->isSized()) return false; + if (!G->hasInitializer()) return false; + if (GlobalWasGeneratedByAsan(G)) return false; // Our own global. + // Touch only those globals that will not be defined in other modules. + // Don't handle ODR linkage types and COMDATs since other modules may be built + // without ASan. + if (G->getLinkage() != GlobalVariable::ExternalLinkage && + G->getLinkage() != GlobalVariable::PrivateLinkage && + G->getLinkage() != GlobalVariable::InternalLinkage) + return false; + if (G->hasComdat()) + return false; + // 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()) + return false; + // For now, just ignore this Global if the alignment is large. + if (G->getAlignment() > MinRedzoneSizeForGlobal()) return false; + + if (G->hasSection()) { + StringRef Section(G->getSection()); + + if (TargetTriple.isOSBinFormatMachO()) { + StringRef ParsedSegment, ParsedSection; + unsigned TAA = 0, StubSize = 0; + bool TAAParsed; + std::string ErrorCode = + MCSectionMachO::ParseSectionSpecifier(Section, ParsedSegment, + ParsedSection, TAA, TAAParsed, + StubSize); + if (!ErrorCode.empty()) { + report_fatal_error("Invalid section specifier '" + ParsedSection + + "': " + ErrorCode + "."); + } + + // 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 (ParsedSegment == "__OBJC" || + (ParsedSegment == "__DATA" && ParsedSection.startswith("__objc_"))) { + DEBUG(dbgs() << "Ignoring ObjC runtime global: " << *G << "\n"); + return false; + } + // 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 (ParsedSegment == "__DATA" && ParsedSection == "__cfstring") { + DEBUG(dbgs() << "Ignoring CFString: " << *G << "\n"); + return false; + } + // The linker merges the contents of cstring_literals and removes the + // trailing zeroes. + if (ParsedSegment == "__TEXT" && (TAA & MachO::S_CSTRING_LITERALS)) { + DEBUG(dbgs() << "Ignoring a cstring literal: " << *G << "\n"); + return false; + } + } + + // Callbacks put into the CRT initializer/terminator sections + // should not be instrumented. + // See https://code.google.com/p/address-sanitizer/issues/detail?id=305 + // and http://msdn.microsoft.com/en-US/en-en/library/bb918180(v=vs.120).aspx + if (Section.startswith(".CRT")) { + DEBUG(dbgs() << "Ignoring a global initializer callback: " << *G << "\n"); + return false; + } + + // Globals from llvm.metadata aren't emitted, do not instrument them. + if (Section == "llvm.metadata") return false; + } + + return true; +} + +void AddressSanitizerModule::initializeCallbacks(Module &M) { + IRBuilder<> IRB(*C); + // Declare our poisoning and unpoisoning functions. + AsanPoisonGlobals = checkInterfaceFunction(M.getOrInsertFunction( + kAsanPoisonGlobalsName, IRB.getVoidTy(), IntptrTy, nullptr)); + AsanPoisonGlobals->setLinkage(Function::ExternalLinkage); + AsanUnpoisonGlobals = checkInterfaceFunction(M.getOrInsertFunction( + kAsanUnpoisonGlobalsName, IRB.getVoidTy(), nullptr)); + AsanUnpoisonGlobals->setLinkage(Function::ExternalLinkage); + // Declare functions that register/unregister globals. + AsanRegisterGlobals = checkInterfaceFunction(M.getOrInsertFunction( + kAsanRegisterGlobalsName, IRB.getVoidTy(), + IntptrTy, IntptrTy, nullptr)); + AsanRegisterGlobals->setLinkage(Function::ExternalLinkage); + AsanUnregisterGlobals = checkInterfaceFunction(M.getOrInsertFunction( + kAsanUnregisterGlobalsName, + IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr)); + AsanUnregisterGlobals->setLinkage(Function::ExternalLinkage); +} + +// 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 AddressSanitizerModule::InstrumentGlobals(IRBuilder<> &IRB, Module &M) { + GlobalsMD.init(M); + + SmallVector<GlobalVariable *, 16> GlobalsToChange; + + for (auto &G : M.globals()) { + if (ShouldInstrumentGlobal(&G)) + 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; + // const char *module_name; + // size_t has_dynamic_init; + // void *source_location; + // We initialize an array of such structures and pass it to a run-time call. + StructType *GlobalStructTy = + StructType::get(IntptrTy, IntptrTy, IntptrTy, IntptrTy, IntptrTy, + IntptrTy, IntptrTy, nullptr); + SmallVector<Constant *, 16> Initializers(n); + + bool HasDynamicallyInitializedGlobals = false; + + // We shouldn't merge same module names, as this string serves as unique + // module ID in runtime. + GlobalVariable *ModuleName = createPrivateGlobalForString( + M, M.getModuleIdentifier(), /*AllowMerging*/false); + + for (size_t i = 0; i < n; i++) { + static const uint64_t kMaxGlobalRedzone = 1 << 18; + GlobalVariable *G = GlobalsToChange[i]; + + auto MD = GlobalsMD.get(G); + // Create string holding the global name (use global name from metadata + // if it's available, otherwise just write the name of global variable). + GlobalVariable *Name = createPrivateGlobalForString( + M, MD.Name.empty() ? G->getName() : MD.Name, + /*AllowMerging*/ true); + + PointerType *PtrTy = cast<PointerType>(G->getType()); + Type *Ty = PtrTy->getElementType(); + uint64_t SizeInBytes = DL->getTypeAllocSize(Ty); + uint64_t MinRZ = MinRedzoneSizeForGlobal(); + // MinRZ <= RZ <= kMaxGlobalRedzone + // and trying to make RZ to be ~ 1/4 of SizeInBytes. + uint64_t RZ = std::max(MinRZ, + std::min(kMaxGlobalRedzone, + (SizeInBytes / MinRZ / 4) * MinRZ)); + uint64_t RightRedzoneSize = RZ; + // Round up to MinRZ + if (SizeInBytes % MinRZ) + RightRedzoneSize += MinRZ - (SizeInBytes % MinRZ); + assert(((RightRedzoneSize + SizeInBytes) % MinRZ) == 0); + Type *RightRedZoneTy = ArrayType::get(IRB.getInt8Ty(), RightRedzoneSize); + + StructType *NewTy = StructType::get(Ty, RightRedZoneTy, nullptr); + Constant *NewInitializer = ConstantStruct::get( + NewTy, G->getInitializer(), + Constant::getNullValue(RightRedZoneTy), nullptr); + + // Create a new global variable with enough space for a redzone. + GlobalValue::LinkageTypes Linkage = G->getLinkage(); + if (G->isConstant() && Linkage == GlobalValue::PrivateLinkage) + Linkage = GlobalValue::InternalLinkage; + GlobalVariable *NewGlobal = new GlobalVariable( + M, NewTy, G->isConstant(), Linkage, + NewInitializer, "", G, G->getThreadLocalMode()); + NewGlobal->copyAttributesFrom(G); + NewGlobal->setAlignment(MinRZ); + + 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(); + + Constant *SourceLoc; + if (!MD.SourceLoc.empty()) { + auto SourceLocGlobal = createPrivateGlobalForSourceLoc(M, MD.SourceLoc); + SourceLoc = ConstantExpr::getPointerCast(SourceLocGlobal, IntptrTy); + } else { + SourceLoc = ConstantInt::get(IntptrTy, 0); + } + + Initializers[i] = ConstantStruct::get( + GlobalStructTy, ConstantExpr::getPointerCast(NewGlobal, IntptrTy), + ConstantInt::get(IntptrTy, SizeInBytes), + ConstantInt::get(IntptrTy, SizeInBytes + RightRedzoneSize), + ConstantExpr::getPointerCast(Name, IntptrTy), + ConstantExpr::getPointerCast(ModuleName, IntptrTy), + ConstantInt::get(IntptrTy, MD.IsDynInit), SourceLoc, nullptr); + + if (ClInitializers && MD.IsDynInit) + HasDynamicallyInitializedGlobals = true; + + DEBUG(dbgs() << "NEW GLOBAL: " << *NewGlobal << "\n"); + } + + ArrayType *ArrayOfGlobalStructTy = ArrayType::get(GlobalStructTy, n); + GlobalVariable *AllGlobals = new GlobalVariable( + M, ArrayOfGlobalStructTy, false, GlobalVariable::InternalLinkage, + ConstantArray::get(ArrayOfGlobalStructTy, Initializers), ""); + + // Create calls for poisoning before initializers run and unpoisoning after. + if (HasDynamicallyInitializedGlobals) + createInitializerPoisonCalls(M, ModuleName); + 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)); + IRB_Dtor.CreateCall2(AsanUnregisterGlobals, + IRB.CreatePointerCast(AllGlobals, IntptrTy), + ConstantInt::get(IntptrTy, n)); + appendToGlobalDtors(M, AsanDtorFunction, kAsanCtorAndDtorPriority); + + DEBUG(dbgs() << M); + return true; +} + +bool AddressSanitizerModule::runOnModule(Module &M) { + DataLayoutPass *DLP = getAnalysisIfAvailable<DataLayoutPass>(); + if (!DLP) + return false; + DL = &DLP->getDataLayout(); + C = &(M.getContext()); + int LongSize = DL->getPointerSizeInBits(); + IntptrTy = Type::getIntNTy(*C, LongSize); + TargetTriple = Triple(M.getTargetTriple()); + Mapping = getShadowMapping(TargetTriple, LongSize); + initializeCallbacks(M); + + bool Changed = false; + + Function *CtorFunc = M.getFunction(kAsanModuleCtorName); + assert(CtorFunc); + IRBuilder<> IRB(CtorFunc->getEntryBlock().getTerminator()); + + if (ClGlobals) + Changed |= InstrumentGlobals(IRB, M); + + return Changed; +} + +void AddressSanitizer::initializeCallbacks(Module &M) { + IRBuilder<> IRB(*C); + // Create __asan_report* callbacks. + for (size_t AccessIsWrite = 0; AccessIsWrite <= 1; AccessIsWrite++) { + for (size_t AccessSizeIndex = 0; AccessSizeIndex < kNumberOfAccessSizes; + AccessSizeIndex++) { + // IsWrite and TypeSize are encoded in the function name. + std::string Suffix = + (AccessIsWrite ? "store" : "load") + itostr(1 << AccessSizeIndex); + AsanErrorCallback[AccessIsWrite][AccessSizeIndex] = + checkInterfaceFunction( + M.getOrInsertFunction(kAsanReportErrorTemplate + Suffix, + IRB.getVoidTy(), IntptrTy, nullptr)); + AsanMemoryAccessCallback[AccessIsWrite][AccessSizeIndex] = + checkInterfaceFunction( + M.getOrInsertFunction(ClMemoryAccessCallbackPrefix + Suffix, + IRB.getVoidTy(), IntptrTy, nullptr)); + } + } + AsanErrorCallbackSized[0] = checkInterfaceFunction(M.getOrInsertFunction( + kAsanReportLoadN, IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr)); + AsanErrorCallbackSized[1] = checkInterfaceFunction(M.getOrInsertFunction( + kAsanReportStoreN, IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr)); + + AsanMemoryAccessCallbackSized[0] = checkInterfaceFunction( + M.getOrInsertFunction(ClMemoryAccessCallbackPrefix + "loadN", + IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr)); + AsanMemoryAccessCallbackSized[1] = checkInterfaceFunction( + M.getOrInsertFunction(ClMemoryAccessCallbackPrefix + "storeN", + IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr)); + + AsanMemmove = checkInterfaceFunction(M.getOrInsertFunction( + ClMemoryAccessCallbackPrefix + "memmove", IRB.getInt8PtrTy(), + IRB.getInt8PtrTy(), IRB.getInt8PtrTy(), IntptrTy, nullptr)); + AsanMemcpy = checkInterfaceFunction(M.getOrInsertFunction( + ClMemoryAccessCallbackPrefix + "memcpy", IRB.getInt8PtrTy(), + IRB.getInt8PtrTy(), IRB.getInt8PtrTy(), IntptrTy, nullptr)); + AsanMemset = checkInterfaceFunction(M.getOrInsertFunction( + ClMemoryAccessCallbackPrefix + "memset", IRB.getInt8PtrTy(), + IRB.getInt8PtrTy(), IRB.getInt32Ty(), IntptrTy, nullptr)); + + AsanHandleNoReturnFunc = checkInterfaceFunction( + M.getOrInsertFunction(kAsanHandleNoReturnName, IRB.getVoidTy(), nullptr)); + + AsanPtrCmpFunction = checkInterfaceFunction(M.getOrInsertFunction( + kAsanPtrCmp, IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr)); + AsanPtrSubFunction = checkInterfaceFunction(M.getOrInsertFunction( + kAsanPtrSub, IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr)); + // We insert an empty inline asm after __asan_report* to avoid callback merge. + EmptyAsm = InlineAsm::get(FunctionType::get(IRB.getVoidTy(), false), + StringRef(""), StringRef(""), + /*hasSideEffects=*/true); +} + +// virtual +bool AddressSanitizer::doInitialization(Module &M) { + // Initialize the private fields. No one has accessed them before. + DataLayoutPass *DLP = getAnalysisIfAvailable<DataLayoutPass>(); + if (!DLP) + report_fatal_error("data layout missing"); + DL = &DLP->getDataLayout(); + + GlobalsMD.init(M); + + C = &(M.getContext()); + LongSize = DL->getPointerSizeInBits(); + IntptrTy = Type::getIntNTy(*C, LongSize); + TargetTriple = Triple(M.getTargetTriple()); + + AsanCtorFunction = Function::Create( + FunctionType::get(Type::getVoidTy(*C), false), + GlobalValue::InternalLinkage, kAsanModuleCtorName, &M); + BasicBlock *AsanCtorBB = BasicBlock::Create(*C, "", AsanCtorFunction); + // call __asan_init in the module ctor. + IRBuilder<> IRB(ReturnInst::Create(*C, AsanCtorBB)); + AsanInitFunction = checkInterfaceFunction( + M.getOrInsertFunction(kAsanInitName, IRB.getVoidTy(), nullptr)); + AsanInitFunction->setLinkage(Function::ExternalLinkage); + IRB.CreateCall(AsanInitFunction); + + Mapping = getShadowMapping(TargetTriple, LongSize); + + appendToGlobalCtors(M, AsanCtorFunction, kAsanCtorAndDtorPriority); + return true; +} + +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::runOnFunction(Function &F) { + if (&F == AsanCtorFunction) return false; + if (F.getLinkage() == GlobalValue::AvailableExternallyLinkage) return false; + DEBUG(dbgs() << "ASAN instrumenting:\n" << F << "\n"); + initializeCallbacks(*F.getParent()); + + DT = &getAnalysis<DominatorTreeWrapperPass>().getDomTree(); + + // If needed, insert __asan_init before checking for SanitizeAddress attr. + maybeInsertAsanInitAtFunctionEntry(F); + + if (!F.hasFnAttribute(Attribute::SanitizeAddress)) + 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; + SmallVector<BasicBlock*, 16> AllBlocks; + SmallVector<Instruction*, 16> PointerComparisonsOrSubtracts; + int NumAllocas = 0; + bool IsWrite; + unsigned Alignment; + + // Fill the set of memory operations to instrument. + for (auto &BB : F) { + AllBlocks.push_back(&BB); + TempsToInstrument.clear(); + int NumInsnsPerBB = 0; + for (auto &Inst : BB) { + if (LooksLikeCodeInBug11395(&Inst)) return false; + if (Value *Addr = + isInterestingMemoryAccess(&Inst, &IsWrite, &Alignment)) { + if (ClOpt && ClOptSameTemp) { + if (!TempsToInstrument.insert(Addr).second) + continue; // We've seen this temp in the current BB. + } + } else if (ClInvalidPointerPairs && + isInterestingPointerComparisonOrSubtraction(&Inst)) { + PointerComparisonsOrSubtracts.push_back(&Inst); + continue; + } else if (isa<MemIntrinsic>(Inst)) { + // ok, take it. + } else { + if (isa<AllocaInst>(Inst)) + NumAllocas++; + CallSite CS(&Inst); + if (CS) { + // A call inside BB. + TempsToInstrument.clear(); + if (CS.doesNotReturn()) + NoReturnCalls.push_back(CS.getInstruction()); + } + continue; + } + ToInstrument.push_back(&Inst); + NumInsnsPerBB++; + if (NumInsnsPerBB >= ClMaxInsnsToInstrumentPerBB) + break; + } + } + + bool UseCalls = false; + if (ClInstrumentationWithCallsThreshold >= 0 && + ToInstrument.size() > (unsigned)ClInstrumentationWithCallsThreshold) + UseCalls = true; + + // Instrument. + int NumInstrumented = 0; + for (auto Inst : ToInstrument) { + if (ClDebugMin < 0 || ClDebugMax < 0 || + (NumInstrumented >= ClDebugMin && NumInstrumented <= ClDebugMax)) { + if (isInterestingMemoryAccess(Inst, &IsWrite, &Alignment)) + instrumentMop(Inst, UseCalls); + else + instrumentMemIntrinsic(cast<MemIntrinsic>(Inst)); + } + NumInstrumented++; + } + + FunctionStackPoisoner FSP(F, *this); + bool ChangedStack = FSP.runOnFunction(); + + // 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 (auto CI : NoReturnCalls) { + IRBuilder<> IRB(CI); + IRB.CreateCall(AsanHandleNoReturnFunc); + } + + for (auto Inst : PointerComparisonsOrSubtracts) { + instrumentPointerComparisonOrSubtraction(Inst); + NumInstrumented++; + } + + bool res = NumInstrumented > 0 || ChangedStack || !NoReturnCalls.empty(); + + DEBUG(dbgs() << "ASAN done instrumenting: " << res << " " << F << "\n"); + + return res; +} + +// 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; +} + +void FunctionStackPoisoner::initializeCallbacks(Module &M) { + IRBuilder<> IRB(*C); + for (int i = 0; i <= kMaxAsanStackMallocSizeClass; i++) { + std::string Suffix = itostr(i); + AsanStackMallocFunc[i] = checkInterfaceFunction(M.getOrInsertFunction( + kAsanStackMallocNameTemplate + Suffix, IntptrTy, IntptrTy, nullptr)); + AsanStackFreeFunc[i] = checkInterfaceFunction( + M.getOrInsertFunction(kAsanStackFreeNameTemplate + Suffix, + IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr)); + } + AsanPoisonStackMemoryFunc = checkInterfaceFunction( + M.getOrInsertFunction(kAsanPoisonStackMemoryName, IRB.getVoidTy(), + IntptrTy, IntptrTy, nullptr)); + AsanUnpoisonStackMemoryFunc = checkInterfaceFunction( + M.getOrInsertFunction(kAsanUnpoisonStackMemoryName, IRB.getVoidTy(), + IntptrTy, IntptrTy, nullptr)); +} + +void +FunctionStackPoisoner::poisonRedZones(ArrayRef<uint8_t> ShadowBytes, + IRBuilder<> &IRB, Value *ShadowBase, + bool DoPoison) { + size_t n = ShadowBytes.size(); + size_t i = 0; + // We need to (un)poison n bytes of stack shadow. Poison as many as we can + // using 64-bit stores (if we are on 64-bit arch), then poison the rest + // with 32-bit stores, then with 16-byte stores, then with 8-byte stores. + for (size_t LargeStoreSizeInBytes = ASan.LongSize / 8; + LargeStoreSizeInBytes != 0; LargeStoreSizeInBytes /= 2) { + for (; i + LargeStoreSizeInBytes - 1 < n; i += LargeStoreSizeInBytes) { + uint64_t Val = 0; + for (size_t j = 0; j < LargeStoreSizeInBytes; j++) { + if (ASan.DL->isLittleEndian()) + Val |= (uint64_t)ShadowBytes[i + j] << (8 * j); + else + Val = (Val << 8) | ShadowBytes[i + j]; + } + if (!Val) continue; + Value *Ptr = IRB.CreateAdd(ShadowBase, ConstantInt::get(IntptrTy, i)); + Type *StoreTy = Type::getIntNTy(*C, LargeStoreSizeInBytes * 8); + Value *Poison = ConstantInt::get(StoreTy, DoPoison ? Val : 0); + IRB.CreateStore(Poison, IRB.CreateIntToPtr(Ptr, StoreTy->getPointerTo())); + } + } +} + +// Fake stack allocator (asan_fake_stack.h) has 11 size classes +// for every power of 2 from kMinStackMallocSize to kMaxAsanStackMallocSizeClass +static int StackMallocSizeClass(uint64_t LocalStackSize) { + assert(LocalStackSize <= kMaxStackMallocSize); + uint64_t MaxSize = kMinStackMallocSize; + for (int i = 0; ; i++, MaxSize *= 2) + if (LocalStackSize <= MaxSize) + return i; + llvm_unreachable("impossible LocalStackSize"); +} + +// Set Size bytes starting from ShadowBase to kAsanStackAfterReturnMagic. +// We can not use MemSet intrinsic because it may end up calling the actual +// memset. Size is a multiple of 8. +// Currently this generates 8-byte stores on x86_64; it may be better to +// generate wider stores. +void FunctionStackPoisoner::SetShadowToStackAfterReturnInlined( + IRBuilder<> &IRB, Value *ShadowBase, int Size) { + assert(!(Size % 8)); + assert(kAsanStackAfterReturnMagic == 0xf5); + for (int i = 0; i < Size; i += 8) { + Value *p = IRB.CreateAdd(ShadowBase, ConstantInt::get(IntptrTy, i)); + IRB.CreateStore(ConstantInt::get(IRB.getInt64Ty(), 0xf5f5f5f5f5f5f5f5ULL), + IRB.CreateIntToPtr(p, IRB.getInt64Ty()->getPointerTo())); + } +} + +static DebugLoc getFunctionEntryDebugLocation(Function &F) { + for (const auto &Inst : F.getEntryBlock()) + if (!isa<AllocaInst>(Inst)) + return Inst.getDebugLoc(); + return DebugLoc(); +} + +PHINode *FunctionStackPoisoner::createPHI(IRBuilder<> &IRB, Value *Cond, + Value *ValueIfTrue, + Instruction *ThenTerm, + Value *ValueIfFalse) { + PHINode *PHI = IRB.CreatePHI(IntptrTy, 2); + BasicBlock *CondBlock = cast<Instruction>(Cond)->getParent(); + PHI->addIncoming(ValueIfFalse, CondBlock); + BasicBlock *ThenBlock = ThenTerm->getParent(); + PHI->addIncoming(ValueIfTrue, ThenBlock); + return PHI; +} + +Value *FunctionStackPoisoner::createAllocaForLayout( + IRBuilder<> &IRB, const ASanStackFrameLayout &L, bool Dynamic) { + AllocaInst *Alloca; + if (Dynamic) { + Alloca = IRB.CreateAlloca(IRB.getInt8Ty(), + ConstantInt::get(IRB.getInt64Ty(), L.FrameSize), + "MyAlloca"); + } else { + Alloca = IRB.CreateAlloca(ArrayType::get(IRB.getInt8Ty(), L.FrameSize), + nullptr, "MyAlloca"); + assert(Alloca->isStaticAlloca()); + } + assert((ClRealignStack & (ClRealignStack - 1)) == 0); + size_t FrameAlignment = std::max(L.FrameAlignment, (size_t)ClRealignStack); + Alloca->setAlignment(FrameAlignment); + return IRB.CreatePointerCast(Alloca, IntptrTy); +} + +void FunctionStackPoisoner::poisonStack() { + assert(AllocaVec.size() > 0 || DynamicAllocaVec.size() > 0); + + if (ClInstrumentAllocas) + // Handle dynamic allocas. + for (auto &AllocaCall : DynamicAllocaVec) + handleDynamicAllocaCall(AllocaCall); + + if (AllocaVec.size() == 0) return; + + int StackMallocIdx = -1; + DebugLoc EntryDebugLocation = getFunctionEntryDebugLocation(F); + + Instruction *InsBefore = AllocaVec[0]; + IRBuilder<> IRB(InsBefore); + IRB.SetCurrentDebugLocation(EntryDebugLocation); + + SmallVector<ASanStackVariableDescription, 16> SVD; + SVD.reserve(AllocaVec.size()); + for (AllocaInst *AI : AllocaVec) { + ASanStackVariableDescription D = { AI->getName().data(), + getAllocaSizeInBytes(AI), + AI->getAlignment(), AI, 0}; + SVD.push_back(D); + } + // Minimal header size (left redzone) is 4 pointers, + // i.e. 32 bytes on 64-bit platforms and 16 bytes in 32-bit platforms. + size_t MinHeaderSize = ASan.LongSize / 2; + ASanStackFrameLayout L; + ComputeASanStackFrameLayout(SVD, 1UL << Mapping.Scale, MinHeaderSize, &L); + DEBUG(dbgs() << L.DescriptionString << " --- " << L.FrameSize << "\n"); + uint64_t LocalStackSize = L.FrameSize; + bool DoStackMalloc = + ClUseAfterReturn && LocalStackSize <= kMaxStackMallocSize; + // Don't do dynamic alloca in presence of inline asm: too often it + // makes assumptions on which registers are available. + bool DoDynamicAlloca = ClDynamicAllocaStack && !HasNonEmptyInlineAsm; + + Value *StaticAlloca = + DoDynamicAlloca ? nullptr : createAllocaForLayout(IRB, L, false); + + Value *FakeStack; + Value *LocalStackBase; + + if (DoStackMalloc) { + // void *FakeStack = __asan_option_detect_stack_use_after_return + // ? __asan_stack_malloc_N(LocalStackSize) + // : nullptr; + // void *LocalStackBase = (FakeStack) ? FakeStack : alloca(LocalStackSize); + Constant *OptionDetectUAR = F.getParent()->getOrInsertGlobal( + kAsanOptionDetectUAR, IRB.getInt32Ty()); + Value *UARIsEnabled = + IRB.CreateICmpNE(IRB.CreateLoad(OptionDetectUAR), + Constant::getNullValue(IRB.getInt32Ty())); + Instruction *Term = + SplitBlockAndInsertIfThen(UARIsEnabled, InsBefore, false); + IRBuilder<> IRBIf(Term); + IRBIf.SetCurrentDebugLocation(EntryDebugLocation); + StackMallocIdx = StackMallocSizeClass(LocalStackSize); + assert(StackMallocIdx <= kMaxAsanStackMallocSizeClass); + Value *FakeStackValue = + IRBIf.CreateCall(AsanStackMallocFunc[StackMallocIdx], + ConstantInt::get(IntptrTy, LocalStackSize)); + IRB.SetInsertPoint(InsBefore); + IRB.SetCurrentDebugLocation(EntryDebugLocation); + FakeStack = createPHI(IRB, UARIsEnabled, FakeStackValue, Term, + ConstantInt::get(IntptrTy, 0)); + + Value *NoFakeStack = + IRB.CreateICmpEQ(FakeStack, Constant::getNullValue(IntptrTy)); + Term = SplitBlockAndInsertIfThen(NoFakeStack, InsBefore, false); + IRBIf.SetInsertPoint(Term); + IRBIf.SetCurrentDebugLocation(EntryDebugLocation); + Value *AllocaValue = + DoDynamicAlloca ? createAllocaForLayout(IRBIf, L, true) : StaticAlloca; + IRB.SetInsertPoint(InsBefore); + IRB.SetCurrentDebugLocation(EntryDebugLocation); + LocalStackBase = createPHI(IRB, NoFakeStack, AllocaValue, Term, FakeStack); + } else { + // void *FakeStack = nullptr; + // void *LocalStackBase = alloca(LocalStackSize); + FakeStack = ConstantInt::get(IntptrTy, 0); + LocalStackBase = + DoDynamicAlloca ? createAllocaForLayout(IRB, L, true) : StaticAlloca; + } + + // Insert poison calls for lifetime intrinsics for alloca. + bool HavePoisonedAllocas = false; + for (const auto &APC : AllocaPoisonCallVec) { + assert(APC.InsBefore); + assert(APC.AI); + IRBuilder<> IRB(APC.InsBefore); + poisonAlloca(APC.AI, APC.Size, IRB, APC.DoPoison); + HavePoisonedAllocas |= APC.DoPoison; + } + + // Replace Alloca instructions with base+offset. + for (const auto &Desc : SVD) { + AllocaInst *AI = Desc.AI; + Value *NewAllocaPtr = IRB.CreateIntToPtr( + IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy, Desc.Offset)), + AI->getType()); + replaceDbgDeclareForAlloca(AI, NewAllocaPtr, DIB); + AI->replaceAllUsesWith(NewAllocaPtr); + } + + // The left-most redzone has enough space for at least 4 pointers. + // Write the Magic value to redzone[0]. + Value *BasePlus0 = IRB.CreateIntToPtr(LocalStackBase, IntptrPtrTy); + IRB.CreateStore(ConstantInt::get(IntptrTy, kCurrentStackFrameMagic), + BasePlus0); + // Write the frame description constant to redzone[1]. + Value *BasePlus1 = IRB.CreateIntToPtr( + IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy, ASan.LongSize/8)), + IntptrPtrTy); + GlobalVariable *StackDescriptionGlobal = + createPrivateGlobalForString(*F.getParent(), L.DescriptionString, + /*AllowMerging*/true); + Value *Description = IRB.CreatePointerCast(StackDescriptionGlobal, + IntptrTy); + IRB.CreateStore(Description, BasePlus1); + // Write the PC to redzone[2]. + Value *BasePlus2 = IRB.CreateIntToPtr( + IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy, + 2 * ASan.LongSize/8)), + IntptrPtrTy); + IRB.CreateStore(IRB.CreatePointerCast(&F, IntptrTy), BasePlus2); + + // Poison the stack redzones at the entry. + Value *ShadowBase = ASan.memToShadow(LocalStackBase, IRB); + poisonRedZones(L.ShadowBytes, IRB, ShadowBase, true); + + // (Un)poison the stack before all ret instructions. + for (auto Ret : RetVec) { + IRBuilder<> IRBRet(Ret); + // Mark the current frame as retired. + IRBRet.CreateStore(ConstantInt::get(IntptrTy, kRetiredStackFrameMagic), + BasePlus0); + if (DoStackMalloc) { + assert(StackMallocIdx >= 0); + // if FakeStack != 0 // LocalStackBase == FakeStack + // // In use-after-return mode, poison the whole stack frame. + // if StackMallocIdx <= 4 + // // For small sizes inline the whole thing: + // memset(ShadowBase, kAsanStackAfterReturnMagic, ShadowSize); + // **SavedFlagPtr(FakeStack) = 0 + // else + // __asan_stack_free_N(FakeStack, LocalStackSize) + // else + // <This is not a fake stack; unpoison the redzones> + Value *Cmp = + IRBRet.CreateICmpNE(FakeStack, Constant::getNullValue(IntptrTy)); + TerminatorInst *ThenTerm, *ElseTerm; + SplitBlockAndInsertIfThenElse(Cmp, Ret, &ThenTerm, &ElseTerm); + + IRBuilder<> IRBPoison(ThenTerm); + if (StackMallocIdx <= 4) { + int ClassSize = kMinStackMallocSize << StackMallocIdx; + SetShadowToStackAfterReturnInlined(IRBPoison, ShadowBase, + ClassSize >> Mapping.Scale); + Value *SavedFlagPtrPtr = IRBPoison.CreateAdd( + FakeStack, + ConstantInt::get(IntptrTy, ClassSize - ASan.LongSize / 8)); + Value *SavedFlagPtr = IRBPoison.CreateLoad( + IRBPoison.CreateIntToPtr(SavedFlagPtrPtr, IntptrPtrTy)); + IRBPoison.CreateStore( + Constant::getNullValue(IRBPoison.getInt8Ty()), + IRBPoison.CreateIntToPtr(SavedFlagPtr, IRBPoison.getInt8PtrTy())); + } else { + // For larger frames call __asan_stack_free_*. + IRBPoison.CreateCall2(AsanStackFreeFunc[StackMallocIdx], FakeStack, + ConstantInt::get(IntptrTy, LocalStackSize)); + } + + IRBuilder<> IRBElse(ElseTerm); + poisonRedZones(L.ShadowBytes, IRBElse, ShadowBase, false); + } else if (HavePoisonedAllocas) { + // If we poisoned some allocas in llvm.lifetime analysis, + // unpoison whole stack frame now. + poisonAlloca(LocalStackBase, LocalStackSize, IRBRet, false); + } else { + poisonRedZones(L.ShadowBytes, IRBRet, ShadowBase, false); + } + } + + if (ClInstrumentAllocas) + // Unpoison dynamic allocas. + for (auto &AllocaCall : DynamicAllocaVec) + unpoisonDynamicAlloca(AllocaCall); + + // We are done. Remove the old unused alloca instructions. + for (auto AI : AllocaVec) + AI->eraseFromParent(); +} + +void FunctionStackPoisoner::poisonAlloca(Value *V, uint64_t Size, + IRBuilder<> &IRB, bool DoPoison) { + // For now just insert the call to ASan runtime. + Value *AddrArg = IRB.CreatePointerCast(V, IntptrTy); + Value *SizeArg = ConstantInt::get(IntptrTy, Size); + IRB.CreateCall2(DoPoison ? AsanPoisonStackMemoryFunc + : AsanUnpoisonStackMemoryFunc, + AddrArg, SizeArg); +} + +// Handling llvm.lifetime intrinsics for a given %alloca: +// (1) collect all llvm.lifetime.xxx(%size, %value) describing the alloca. +// (2) if %size is constant, poison memory for llvm.lifetime.end (to detect +// invalid accesses) and unpoison it for llvm.lifetime.start (the memory +// could be poisoned by previous llvm.lifetime.end instruction, as the +// variable may go in and out of scope several times, e.g. in loops). +// (3) if we poisoned at least one %alloca in a function, +// unpoison the whole stack frame at function exit. + +AllocaInst *FunctionStackPoisoner::findAllocaForValue(Value *V) { + if (AllocaInst *AI = dyn_cast<AllocaInst>(V)) + // We're intested only in allocas we can handle. + return isInterestingAlloca(*AI) ? AI : nullptr; + // See if we've already calculated (or started to calculate) alloca for a + // given value. + AllocaForValueMapTy::iterator I = AllocaForValue.find(V); + if (I != AllocaForValue.end()) + return I->second; + // Store 0 while we're calculating alloca for value V to avoid + // infinite recursion if the value references itself. + AllocaForValue[V] = nullptr; + AllocaInst *Res = nullptr; + if (CastInst *CI = dyn_cast<CastInst>(V)) + Res = findAllocaForValue(CI->getOperand(0)); + else if (PHINode *PN = dyn_cast<PHINode>(V)) { + for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) { + Value *IncValue = PN->getIncomingValue(i); + // Allow self-referencing phi-nodes. + if (IncValue == PN) continue; + AllocaInst *IncValueAI = findAllocaForValue(IncValue); + // AI for incoming values should exist and should all be equal. + if (IncValueAI == nullptr || (Res != nullptr && IncValueAI != Res)) + return nullptr; + Res = IncValueAI; + } + } + if (Res) + AllocaForValue[V] = Res; + return Res; +} + +// Compute PartialRzMagic for dynamic alloca call. PartialRzMagic is +// constructed from two separate 32-bit numbers: PartialRzMagic = Val1 | Val2. +// (1) Val1 is resposible for forming base value for PartialRzMagic, containing +// only 00 for fully addressable and 0xcb for fully poisoned bytes for each +// 8-byte chunk of user memory respectively. +// (2) Val2 forms the value for marking first poisoned byte in shadow memory +// with appropriate value (0x01 - 0x07 or 0xcb if Padding % 8 == 0). + +// Shift = Padding & ~7; // the number of bits we need to shift to access first +// chunk in shadow memory, containing nonzero bytes. +// Example: +// Padding = 21 Padding = 16 +// Shadow: |00|00|05|cb| Shadow: |00|00|cb|cb| +// ^ ^ +// | | +// Shift = 21 & ~7 = 16 Shift = 16 & ~7 = 16 +// +// Val1 = 0xcbcbcbcb << Shift; +// PartialBits = Padding ? Padding & 7 : 0xcb; +// Val2 = PartialBits << Shift; +// Result = Val1 | Val2; +Value *FunctionStackPoisoner::computePartialRzMagic(Value *PartialSize, + IRBuilder<> &IRB) { + PartialSize = IRB.CreateIntCast(PartialSize, IRB.getInt32Ty(), false); + Value *Shift = IRB.CreateAnd(PartialSize, IRB.getInt32(~7)); + unsigned Val1Int = kAsanAllocaPartialVal1; + unsigned Val2Int = kAsanAllocaPartialVal2; + if (!ASan.DL->isLittleEndian()) { + Val1Int = sys::getSwappedBytes(Val1Int); + Val2Int = sys::getSwappedBytes(Val2Int); + } + Value *Val1 = shiftAllocaMagic(IRB.getInt32(Val1Int), IRB, Shift); + Value *PartialBits = IRB.CreateAnd(PartialSize, IRB.getInt32(7)); + // For BigEndian get 0x000000YZ -> 0xYZ000000. + if (ASan.DL->isBigEndian()) + PartialBits = IRB.CreateShl(PartialBits, IRB.getInt32(24)); + Value *Val2 = IRB.getInt32(Val2Int); + Value *Cond = + IRB.CreateICmpNE(PartialBits, Constant::getNullValue(IRB.getInt32Ty())); + Val2 = IRB.CreateSelect(Cond, shiftAllocaMagic(PartialBits, IRB, Shift), + shiftAllocaMagic(Val2, IRB, Shift)); + return IRB.CreateOr(Val1, Val2); +} + +void FunctionStackPoisoner::handleDynamicAllocaCall( + DynamicAllocaCall &AllocaCall) { + AllocaInst *AI = AllocaCall.AI; + if (!doesDominateAllExits(AI)) { + // We do not yet handle complex allocas + AllocaCall.Poison = false; + return; + } + + IRBuilder<> IRB(AI); + + PointerType *Int32PtrTy = PointerType::getUnqual(IRB.getInt32Ty()); + const unsigned Align = std::max(kAllocaRzSize, AI->getAlignment()); + const uint64_t AllocaRedzoneMask = kAllocaRzSize - 1; + + Value *Zero = Constant::getNullValue(IntptrTy); + Value *AllocaRzSize = ConstantInt::get(IntptrTy, kAllocaRzSize); + Value *AllocaRzMask = ConstantInt::get(IntptrTy, AllocaRedzoneMask); + Value *NotAllocaRzMask = ConstantInt::get(IntptrTy, ~AllocaRedzoneMask); + + // Since we need to extend alloca with additional memory to locate + // redzones, and OldSize is number of allocated blocks with + // ElementSize size, get allocated memory size in bytes by + // OldSize * ElementSize. + unsigned ElementSize = ASan.DL->getTypeAllocSize(AI->getAllocatedType()); + Value *OldSize = IRB.CreateMul(AI->getArraySize(), + ConstantInt::get(IntptrTy, ElementSize)); + + // PartialSize = OldSize % 32 + Value *PartialSize = IRB.CreateAnd(OldSize, AllocaRzMask); + + // Misalign = kAllocaRzSize - PartialSize; + Value *Misalign = IRB.CreateSub(AllocaRzSize, PartialSize); + + // PartialPadding = Misalign != kAllocaRzSize ? Misalign : 0; + Value *Cond = IRB.CreateICmpNE(Misalign, AllocaRzSize); + Value *PartialPadding = IRB.CreateSelect(Cond, Misalign, Zero); + + // AdditionalChunkSize = Align + PartialPadding + kAllocaRzSize + // Align is added to locate left redzone, PartialPadding for possible + // partial redzone and kAllocaRzSize for right redzone respectively. + Value *AdditionalChunkSize = IRB.CreateAdd( + ConstantInt::get(IntptrTy, Align + kAllocaRzSize), PartialPadding); + + Value *NewSize = IRB.CreateAdd(OldSize, AdditionalChunkSize); + + // Insert new alloca with new NewSize and Align params. + AllocaInst *NewAlloca = IRB.CreateAlloca(IRB.getInt8Ty(), NewSize); + NewAlloca->setAlignment(Align); + + // NewAddress = Address + Align + Value *NewAddress = IRB.CreateAdd(IRB.CreatePtrToInt(NewAlloca, IntptrTy), + ConstantInt::get(IntptrTy, Align)); + + Value *NewAddressPtr = IRB.CreateIntToPtr(NewAddress, AI->getType()); + + // LeftRzAddress = NewAddress - kAllocaRzSize + Value *LeftRzAddress = IRB.CreateSub(NewAddress, AllocaRzSize); + + // Poisoning left redzone. + AllocaCall.LeftRzAddr = ASan.memToShadow(LeftRzAddress, IRB); + IRB.CreateStore(ConstantInt::get(IRB.getInt32Ty(), kAsanAllocaLeftMagic), + IRB.CreateIntToPtr(AllocaCall.LeftRzAddr, Int32PtrTy)); + + // PartialRzAligned = PartialRzAddr & ~AllocaRzMask + Value *PartialRzAddr = IRB.CreateAdd(NewAddress, OldSize); + Value *PartialRzAligned = IRB.CreateAnd(PartialRzAddr, NotAllocaRzMask); + + // Poisoning partial redzone. + Value *PartialRzMagic = computePartialRzMagic(PartialSize, IRB); + Value *PartialRzShadowAddr = ASan.memToShadow(PartialRzAligned, IRB); + IRB.CreateStore(PartialRzMagic, + IRB.CreateIntToPtr(PartialRzShadowAddr, Int32PtrTy)); + + // RightRzAddress + // = (PartialRzAddr + AllocaRzMask) & ~AllocaRzMask + Value *RightRzAddress = IRB.CreateAnd( + IRB.CreateAdd(PartialRzAddr, AllocaRzMask), NotAllocaRzMask); + + // Poisoning right redzone. + AllocaCall.RightRzAddr = ASan.memToShadow(RightRzAddress, IRB); + IRB.CreateStore(ConstantInt::get(IRB.getInt32Ty(), kAsanAllocaRightMagic), + IRB.CreateIntToPtr(AllocaCall.RightRzAddr, Int32PtrTy)); + + // Replace all uses of AddessReturnedByAlloca with NewAddress. + AI->replaceAllUsesWith(NewAddressPtr); + + // We are done. Erase old alloca and store left, partial and right redzones + // shadow addresses for future unpoisoning. + AI->eraseFromParent(); + NumInstrumentedDynamicAllocas++; +} |
