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llvm-6502/lib/Transforms/Instrumentation/AddressSanitizer.cpp
Evgeniy Stepanov d8313be410 ASan: use getTypeAllocSize instead of getTypeStoreSize. 
This change replaces getTypeStoreSize with getTypeAllocSize in AddressSanitizer
instrumentation for stack allocations.

One case where old behaviour produced undesired results is an optimization in
InstCombine pass (PromoteCastOfAllocation), which can replace  alloca(T) with
alloca(S), where S has the same AllocSize, but a smaller StoreSize. Another
case is memcpy(long double => long double), where ASan will poison bytes 10-15
of a stack-allocated long double (StoreSize  10, AllocSize 16,
sizeof(long double) = 16).

See http://llvm.org/bugs/show_bug.cgi?id=12047 for more context.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@151887 91177308-0d34-0410-b5e6-96231b3b80d8
2012-03-02 10:41:08 +00:00

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//===-- 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 "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/MemoryBuffer.h"
#include "llvm/Support/Regex.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 {
// Blacklisted functions are not instrumented.
// The blacklist file contains one or more lines like this:
// ---
// fun:FunctionWildCard
// ---
// This is similar to the "ignore" feature of ThreadSanitizer.
// http://code.google.com/p/data-race-test/wiki/ThreadSanitizerIgnores
class BlackList {
public:
BlackList(const std::string &Path);
bool isIn(const Function &F);
private:
Regex *Functions;
};
/// 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<BlackList> 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->getTypeStoreSizeInBits(Ty) / 8;
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 BlackList(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);
// 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);
GlobalValue *asan_mapping_scale =
new GlobalVariable(M, IntptrTy, true, GlobalValue::LinkOnceODRLinkage,
ConstantInt::get(IntptrTy, MappingScale),
kAsanMappingScaleName);
// Read these globals, otherwise they may be optimized away.
IRB.CreateLoad(asan_mapping_scale, true);
IRB.CreateLoad(asan_mapping_offset, 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;
}
BlackList::BlackList(const std::string &Path) {
Functions = NULL;
const char *kFunPrefix = "fun:";
if (!ClBlackListFile.size()) return;
std::string Fun;
OwningPtr<MemoryBuffer> File;
if (error_code EC = MemoryBuffer::getFile(ClBlackListFile.c_str(), File)) {
report_fatal_error("Can't open blacklist file " + ClBlackListFile + ": " +
EC.message());
}
MemoryBuffer *Buff = File.take();
const char *Data = Buff->getBufferStart();
size_t DataLen = Buff->getBufferSize();
SmallVector<StringRef, 16> Lines;
SplitString(StringRef(Data, DataLen), Lines, "\n\r");
for (size_t i = 0, numLines = Lines.size(); i < numLines; i++) {
if (Lines[i].startswith(kFunPrefix)) {
std::string ThisFunc = Lines[i].substr(strlen(kFunPrefix));
std::string ThisFuncRE;
// add ThisFunc replacing * with .*
for (size_t j = 0, n = ThisFunc.size(); j < n; j++) {
if (ThisFunc[j] == '*')
ThisFuncRE += '.';
ThisFuncRE += ThisFunc[j];
}
// Check that the regexp is valid.
Regex CheckRE(ThisFuncRE);
std::string Error;
if (!CheckRE.isValid(Error))
report_fatal_error("malformed blacklist regex: " + ThisFunc +
": " + Error);
// Append to the final regexp.
if (Fun.size())
Fun += "|";
Fun += ThisFuncRE;
}
}
if (Fun.size()) {
Functions = new Regex(Fun);
}
}
bool BlackList::isIn(const Function &F) {
if (Functions) {
bool Res = Functions->match(F.getName());
return Res;
}
return false;
}
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