#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/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"
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 kMIPS64_ShadowOffset64 = 1ULL << 37;
+static const uint64_t kAArch64_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
"__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_v4";
+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";
// 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.
"asan-memory-access-callback-prefix",
cl::desc("Prefix for memory access callbacks"), cl::Hidden,
cl::init("__asan_"));
-
-// This is an experimental feature that will allow to choose between
-// instrumented and non-instrumented code at link-time.
-// If this option is on, just before instrumenting a function we create its
-// clone; if the function is not changed by asan the clone is deleted.
-// If we end up with a clone, we put the instrumented function into a section
-// called "ASAN" and the uninstrumented function into a section called "NOASAN".
-//
-// This is still a prototype, we need to figure out a way to keep two copies of
-// a function so that the linker can easily choose one of them.
-static cl::opt<bool> ClKeepUninstrumented("asan-keep-uninstrumented-functions",
- cl::desc("Keep uninstrumented copies of functions"),
- cl::Hidden, cl::init(false));
+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
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(true));
+
// Debug flags.
static cl::opt<int> ClDebug("asan-debug", cl::desc("debug"), cl::Hidden,
cl::init(0));
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,
assert(MDN->getNumOperands() == 3);
MDString *MDFilename = cast<MDString>(MDN->getOperand(0));
Filename = MDFilename->getString();
- LineNo = cast<ConstantInt>(MDN->getOperand(1))->getLimitedValue();
- ColumnNo = cast<ConstantInt>(MDN->getOperand(2))->getLimitedValue();
+ LineNo =
+ mdconst::extract<ConstantInt>(MDN->getOperand(1))->getLimitedValue();
+ ColumnNo =
+ mdconst::extract<ConstantInt>(MDN->getOperand(2))->getLimitedValue();
}
};
for (auto MDN : Globals->operands()) {
// Metadata node contains the global and the fields of "Entry".
assert(MDN->getNumOperands() == 5);
- Value *V = MDN->getOperand(0);
+ auto *GV = mdconst::extract_or_null<GlobalVariable>(MDN->getOperand(0));
// The optimizer may optimize away a global entirely.
- if (!V)
+ if (!GV)
continue;
- GlobalVariable *GV = cast<GlobalVariable>(V);
// We can already have an entry for GV if it was merged with another
// global.
Entry &E = Entries[GV];
- if (Value *Loc = MDN->getOperand(1))
- E.SourceLoc.parse(cast<MDNode>(Loc));
- if (Value *Name = MDN->getOperand(2)) {
- MDString *MDName = cast<MDString>(Name);
- E.Name = MDName->getString();
- }
- ConstantInt *IsDynInit = cast<ConstantInt>(MDN->getOperand(3));
+ 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 = cast<ConstantInt>(MDN->getOperand(4));
+ ConstantInt *IsBlacklisted =
+ mdconst::extract<ConstantInt>(MDN->getOperand(4));
E.IsBlacklisted |= IsBlacklisted->isOne();
}
}
bool OrShadowOffset;
};
-static ShadowMapping getShadowMapping(const Module &M, int LongSize) {
- llvm::Triple TargetTriple(M.getTargetTriple());
+static ShadowMapping getShadowMapping(Triple &TargetTriple, int LongSize) {
bool IsAndroid = TargetTriple.getEnvironment() == llvm::Triple::Android;
bool IsIOS = TargetTriple.isiOS();
- bool IsFreeBSD = TargetTriple.getOS() == llvm::Triple::FreeBSD;
- bool IsLinux = TargetTriple.getOS() == llvm::Triple::Linux;
+ 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;
TargetTriple.getArch() == llvm::Triple::mipsel;
bool IsMIPS64 = TargetTriple.getArch() == llvm::Triple::mips64 ||
TargetTriple.getArch() == llvm::Triple::mips64el;
+ bool IsAArch64 = TargetTriple.getArch() == llvm::Triple::aarch64;
+ bool IsWindows = TargetTriple.isOSWindows();
ShadowMapping Mapping;
Mapping.Offset = kFreeBSD_ShadowOffset32;
else if (IsIOS)
Mapping.Offset = kIOSShadowOffset32;
+ else if (IsWindows)
+ Mapping.Offset = kWindowsShadowOffset32;
else
Mapping.Offset = kDefaultShadowOffset32;
} else { // LongSize == 64
Mapping.Offset = kSmallX86_64ShadowOffset;
else if (IsMIPS64)
Mapping.Offset = kMIPS64_ShadowOffset64;
+ else if (IsAArch64)
+ Mapping.Offset = kAArch64_ShadowOffset64;
else
Mapping.Offset = kDefaultShadowOffset64;
}
/// AddressSanitizer: instrument the code in module to find memory bugs.
struct AddressSanitizer : public FunctionPass {
- AddressSanitizer() : FunctionPass(ID) {}
+ 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,
bool doInitialization(Module &M) override;
static char ID; // Pass identification, replacement for typeid
+ DominatorTree &getDominatorTree() const { return *DT; }
+
private:
void initializeCallbacks(Module &M);
LLVMContext *C;
const DataLayout *DL;
+ Triple TargetTriple;
int LongSize;
Type *IntptrTy;
ShadowMapping Mapping;
+ DominatorTree *DT;
Function *AsanCtorFunction;
Function *AsanInitFunction;
Function *AsanHandleNoReturnFunc;
Type *IntptrTy;
LLVMContext *C;
const DataLayout *DL;
+ Triple TargetTriple;
ShadowMapping Mapping;
Function *AsanPoisonGlobals;
Function *AsanUnpoisonGlobals;
};
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()), C(ASan.C),
- IntptrTy(ASan.IntptrTy), IntptrPtrTy(PointerType::get(IntptrTy, 0)),
- Mapping(ASan.Mapping),
- StackAlignment(1 << Mapping.Scale) {}
+ : 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;
for (BasicBlock *BB : depth_first(&F.getEntryBlock()))
visit(*BB);
- if (AllocaVec.empty()) return false;
+ if (AllocaVec.empty() && DynamicAllocaVec.empty()) return false;
initializeCallbacks(*F.getParent());
return true;
}
- // Finds all static Alloca instructions and puts
+ // Finds all Alloca instructions and puts
// poisoned red zones around all of them.
// Then unpoison everything back before the function returns.
void poisonStack();
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());
- AllocaVec.push_back(&AI);
+ if (isDynamicAlloca(AI))
+ DynamicAllocaVec.push_back(DynamicAllocaCall(&AI));
+ else
+ AllocaVec.push_back(&AI);
}
/// \brief Collect lifetime intrinsic calls to check for use-after-scope
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.isArrayAllocation() && AI.isStaticAlloca() &&
- AI.getAllocatedType()->isSized() &&
+ return (AI.getAllocatedType()->isSized() &&
// alloca() may be called with 0 size, ignore it.
getAllocaSizeInBytes(&AI) > 0);
}
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(AddressSanitizer, "asan",
+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() {
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.startswith("__OBJC,") ||
- Section.startswith("__DATA, __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 (Section.startswith("__DATA,__cfstring")) {
- DEBUG(dbgs() << "Ignoring CFString: " << *G << "\n");
- return false;
- }
- // The linker merges the contents of cstring_literals and removes the
- // trailing zeroes.
- if (Section.startswith("__TEXT,__cstring,cstring_literals")) {
- DEBUG(dbgs() << "Ignoring a cstring literal: " << *G << "\n");
- return false;
- }
- if (Section.startswith("__TEXT,__objc_methname,cstring_literals")) {
- DEBUG(dbgs() << "Ignoring objc_methname cstring global: " << *G << "\n");
- return false;
- }
+ 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.
C = &(M.getContext());
int LongSize = DL->getPointerSizeInBits();
IntptrTy = Type::getIntNTy(*C, LongSize);
- Mapping = getShadowMapping(M, LongSize);
+ TargetTriple = Triple(M.getTargetTriple());
+ Mapping = getShadowMapping(TargetTriple, LongSize);
initializeCallbacks(M);
bool Changed = false;
C = &(M.getContext());
LongSize = DL->getPointerSizeInBits();
IntptrTy = Type::getIntNTy(*C, LongSize);
+ TargetTriple = Triple(M.getTargetTriple());
AsanCtorFunction = Function::Create(
FunctionType::get(Type::getVoidTy(*C), false),
AsanInitFunction->setLinkage(Function::ExternalLinkage);
IRB.CreateCall(AsanInitFunction);
- Mapping = getShadowMapping(M, LongSize);
+ Mapping = getShadowMapping(TargetTriple, LongSize);
appendToGlobalCtors(M, AsanCtorFunction, kAsanCtorAndDtorPriority);
return true;
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);
}
}
- Function *UninstrumentedDuplicate = nullptr;
- bool LikelyToInstrument =
- !NoReturnCalls.empty() || !ToInstrument.empty() || (NumAllocas > 0);
- if (ClKeepUninstrumented && LikelyToInstrument) {
- ValueToValueMapTy VMap;
- UninstrumentedDuplicate = CloneFunction(&F, VMap, false);
- UninstrumentedDuplicate->removeFnAttr(Attribute::SanitizeAddress);
- UninstrumentedDuplicate->setName("NOASAN_" + F.getName());
- F.getParent()->getFunctionList().push_back(UninstrumentedDuplicate);
- }
-
bool UseCalls = false;
if (ClInstrumentationWithCallsThreshold >= 0 &&
ToInstrument.size() > (unsigned)ClInstrumentationWithCallsThreshold)
DEBUG(dbgs() << "ASAN done instrumenting: " << res << " " << F << "\n");
- if (ClKeepUninstrumented) {
- if (!res) {
- // No instrumentation is done, no need for the duplicate.
- if (UninstrumentedDuplicate)
- UninstrumentedDuplicate->eraseFromParent();
- } else {
- // The function was instrumented. We must have the duplicate.
- assert(UninstrumentedDuplicate);
- UninstrumentedDuplicate->setSection("NOASAN");
- assert(!F.hasSection());
- F.setSection("ASAN");
- }
- }
-
return res;
}
IRBuilder<> IRB(*C);
for (int i = 0; i <= kMaxAsanStackMallocSizeClass; i++) {
std::string Suffix = itostr(i);
- AsanStackMallocFunc[i] = checkInterfaceFunction(
- M.getOrInsertFunction(kAsanStackMallocNameTemplate + Suffix, IntptrTy,
- IntptrTy, IntptrTy, nullptr));
- AsanStackFreeFunc[i] = checkInterfaceFunction(M.getOrInsertFunction(
- kAsanStackFreeNameTemplate + Suffix, IRB.getVoidTy(), IntptrTy,
- IntptrTy, IntptrTy, nullptr));
+ 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(),
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);
+ unpoisonDynamicAlloca(AllocaCall);
+ }
+ }
+
+ if (AllocaVec.size() == 0) return;
+
int StackMallocIdx = -1;
DebugLoc EntryDebugLocation = getFunctionEntryDebugLocation(F);
- assert(AllocaVec.size() > 0);
Instruction *InsBefore = AllocaVec[0];
IRBuilder<> IRB(InsBefore);
IRB.SetCurrentDebugLocation(EntryDebugLocation);
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;
- Type *ByteArrayTy = ArrayType::get(IRB.getInt8Ty(), LocalStackSize);
- AllocaInst *MyAlloca =
- new AllocaInst(ByteArrayTy, "MyAlloca", InsBefore);
- MyAlloca->setDebugLoc(EntryDebugLocation);
- assert((ClRealignStack & (ClRealignStack - 1)) == 0);
- size_t FrameAlignment = std::max(L.FrameAlignment, (size_t)ClRealignStack);
- MyAlloca->setAlignment(FrameAlignment);
- assert(MyAlloca->isStaticAlloca());
- Value *OrigStackBase = IRB.CreatePointerCast(MyAlloca, IntptrTy);
- Value *LocalStackBase = OrigStackBase;
+ Value *StaticAlloca =
+ DoDynamicAlloca ? nullptr : createAllocaForLayout(IRB, L, false);
+
+ Value *FakeStack;
+ Value *LocalStackBase;
if (DoStackMalloc) {
- // LocalStackBase = OrigStackBase
- // if (__asan_option_detect_stack_use_after_return)
- // LocalStackBase = __asan_stack_malloc_N(LocalStackBase, OrigStackBase);
- StackMallocIdx = StackMallocSizeClass(LocalStackSize);
- assert(StackMallocIdx <= kMaxAsanStackMallocSizeClass);
+ // 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 *Cmp = IRB.CreateICmpNE(IRB.CreateLoad(OptionDetectUAR),
- Constant::getNullValue(IRB.getInt32Ty()));
- Instruction *Term = SplitBlockAndInsertIfThen(Cmp, InsBefore, false);
- BasicBlock *CmpBlock = cast<Instruction>(Cmp)->getParent();
+ Value *UARIsEnabled =
+ IRB.CreateICmpNE(IRB.CreateLoad(OptionDetectUAR),
+ Constant::getNullValue(IRB.getInt32Ty()));
+ Instruction *Term =
+ SplitBlockAndInsertIfThen(UARIsEnabled, InsBefore, false);
IRBuilder<> IRBIf(Term);
IRBIf.SetCurrentDebugLocation(EntryDebugLocation);
- LocalStackBase = IRBIf.CreateCall2(
- AsanStackMallocFunc[StackMallocIdx],
- ConstantInt::get(IntptrTy, LocalStackSize), OrigStackBase);
- BasicBlock *SetBlock = cast<Instruction>(LocalStackBase)->getParent();
+ StackMallocIdx = StackMallocSizeClass(LocalStackSize);
+ assert(StackMallocIdx <= kMaxAsanStackMallocSizeClass);
+ Value *FakeStackValue =
+ IRBIf.CreateCall(AsanStackMallocFunc[StackMallocIdx],
+ ConstantInt::get(IntptrTy, LocalStackSize));
IRB.SetInsertPoint(InsBefore);
IRB.SetCurrentDebugLocation(EntryDebugLocation);
- PHINode *Phi = IRB.CreatePHI(IntptrTy, 2);
- Phi->addIncoming(OrigStackBase, CmpBlock);
- Phi->addIncoming(LocalStackBase, SetBlock);
- LocalStackBase = Phi;
+ 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.
Value *NewAllocaPtr = IRB.CreateIntToPtr(
IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy, Desc.Offset)),
AI->getType());
- replaceDbgDeclareForAlloca(AI, NewAllocaPtr, DIB);
+ replaceDbgDeclareForAlloca(AI, NewAllocaPtr, DIB, /*Deref=*/true);
AI->replaceAllUsesWith(NewAllocaPtr);
}
BasePlus0);
if (DoStackMalloc) {
assert(StackMallocIdx >= 0);
- // if LocalStackBase != OrigStackBase:
+ // 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(LocalStackBase) = 0
+ // **SavedFlagPtr(FakeStack) = 0
// else
- // __asan_stack_free_N(LocalStackBase, OrigStackBase)
+ // __asan_stack_free_N(FakeStack, LocalStackSize)
// else
// <This is not a fake stack; unpoison the redzones>
- Value *Cmp = IRBRet.CreateICmpNE(LocalStackBase, OrigStackBase);
+ Value *Cmp =
+ IRBRet.CreateICmpNE(FakeStack, Constant::getNullValue(IntptrTy));
TerminatorInst *ThenTerm, *ElseTerm;
SplitBlockAndInsertIfThenElse(Cmp, Ret, &ThenTerm, &ElseTerm);
SetShadowToStackAfterReturnInlined(IRBPoison, ShadowBase,
ClassSize >> Mapping.Scale);
Value *SavedFlagPtrPtr = IRBPoison.CreateAdd(
- LocalStackBase,
+ FakeStack,
ConstantInt::get(IntptrTy, ClassSize - ASan.LongSize / 8));
Value *SavedFlagPtr = IRBPoison.CreateLoad(
IRBPoison.CreateIntToPtr(SavedFlagPtrPtr, IntptrPtrTy));
IRBPoison.CreateIntToPtr(SavedFlagPtr, IRBPoison.getInt8PtrTy()));
} else {
// For larger frames call __asan_stack_free_*.
- IRBPoison.CreateCall3(AsanStackFreeFunc[StackMallocIdx], LocalStackBase,
- ConstantInt::get(IntptrTy, LocalStackSize),
- OrigStackBase);
+ IRBPoison.CreateCall2(AsanStackFreeFunc[StackMallocIdx], FakeStack,
+ ConstantInt::get(IntptrTy, LocalStackSize));
}
IRBuilder<> IRBElse(ElseTerm);
} else if (HavePoisonedAllocas) {
// If we poisoned some allocas in llvm.lifetime analysis,
// unpoison whole stack frame now.
- assert(LocalStackBase == OrigStackBase);
poisonAlloca(LocalStackBase, LocalStackSize, IRBRet, false);
} else {
poisonRedZones(L.ShadowBytes, IRBRet, ShadowBase, false);
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++;
+}
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