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-rw-r--r--llvm/lib/Transforms/Instrumentation/HWAddressSanitizer.cpp229
1 files changed, 219 insertions, 10 deletions
diff --git a/llvm/lib/Transforms/Instrumentation/HWAddressSanitizer.cpp b/llvm/lib/Transforms/Instrumentation/HWAddressSanitizer.cpp
index 9633f5a5f8d..f09bf25deaf 100644
--- a/llvm/lib/Transforms/Instrumentation/HWAddressSanitizer.cpp
+++ b/llvm/lib/Transforms/Instrumentation/HWAddressSanitizer.cpp
@@ -16,6 +16,7 @@
#include "llvm/ADT/StringExtras.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/ADT/Triple.h"
+#include "llvm/BinaryFormat/ELF.h"
#include "llvm/IR/Attributes.h"
#include "llvm/IR/BasicBlock.h"
#include "llvm/IR/Constant.h"
@@ -52,6 +53,7 @@ using namespace llvm;
#define DEBUG_TYPE "hwasan"
static const char *const kHwasanModuleCtorName = "hwasan.module_ctor";
+static const char *const kHwasanNoteName = "hwasan.note";
static const char *const kHwasanInitName = "__hwasan_init";
static const char *const kHwasanShadowMemoryDynamicAddress =
@@ -112,6 +114,9 @@ static cl::opt<bool> ClGenerateTagsWithCalls(
cl::desc("generate new tags with runtime library calls"), cl::Hidden,
cl::init(false));
+static cl::opt<bool> ClGlobals("hwasan-globals", cl::desc("Instrument globals"),
+ cl::Hidden, cl::init(false));
+
static cl::opt<int> ClMatchAllTag(
"hwasan-match-all-tag",
cl::desc("don't report bad accesses via pointers with this tag"),
@@ -169,16 +174,16 @@ namespace {
class HWAddressSanitizer {
public:
explicit HWAddressSanitizer(Module &M, bool CompileKernel = false,
- bool Recover = false) {
+ bool Recover = false) : M(M) {
this->Recover = ClRecover.getNumOccurrences() > 0 ? ClRecover : Recover;
this->CompileKernel = ClEnableKhwasan.getNumOccurrences() > 0 ?
ClEnableKhwasan : CompileKernel;
- initializeModule(M);
+ initializeModule();
}
bool sanitizeFunction(Function &F);
- void initializeModule(Module &M);
+ void initializeModule();
void initializeCallbacks(Module &M);
@@ -216,8 +221,12 @@ public:
Value *getHwasanThreadSlotPtr(IRBuilder<> &IRB, Type *Ty);
void emitPrologue(IRBuilder<> &IRB, bool WithFrameRecord);
+ void instrumentGlobal(GlobalVariable *GV, uint8_t Tag);
+ void instrumentGlobals();
+
private:
LLVMContext *C;
+ Module &M;
Triple TargetTriple;
FunctionCallee HWAsanMemmove, HWAsanMemcpy, HWAsanMemset;
FunctionCallee HWAsanHandleVfork;
@@ -237,7 +246,7 @@ private:
bool InTls;
void init(Triple &TargetTriple);
- unsigned getAllocaAlignment() const { return 1U << Scale; }
+ unsigned getObjectAlignment() const { return 1U << Scale; }
};
ShadowMapping Mapping;
@@ -245,6 +254,7 @@ private:
Type *Int8PtrTy;
Type *Int8Ty;
Type *Int32Ty;
+ Type *Int64Ty = Type::getInt64Ty(M.getContext());
bool CompileKernel;
bool Recover;
@@ -332,7 +342,7 @@ PreservedAnalyses HWAddressSanitizerPass::run(Module &M,
/// Module-level initialization.
///
/// inserts a call to __hwasan_init to the module's constructor list.
-void HWAddressSanitizer::initializeModule(Module &M) {
+void HWAddressSanitizer::initializeModule() {
LLVM_DEBUG(dbgs() << "Init " << M.getName() << "\n");
auto &DL = M.getDataLayout();
@@ -361,6 +371,16 @@ void HWAddressSanitizer::initializeModule(Module &M) {
Ctor->setComdat(CtorComdat);
appendToGlobalCtors(M, Ctor, 0, Ctor);
});
+
+ // Older versions of Android do not have the required runtime support for
+ // global instrumentation. On other platforms we currently require using the
+ // latest version of the runtime.
+ bool InstrumentGlobals =
+ !TargetTriple.isAndroid() || !TargetTriple.isAndroidVersionLT(30);
+ if (ClGlobals.getNumOccurrences())
+ InstrumentGlobals = ClGlobals;
+ if (InstrumentGlobals)
+ instrumentGlobals();
}
if (!TargetTriple.isAndroid()) {
@@ -716,7 +736,7 @@ static uint64_t getAllocaSizeInBytes(const AllocaInst &AI) {
bool HWAddressSanitizer::tagAlloca(IRBuilder<> &IRB, AllocaInst *AI,
Value *Tag, size_t Size) {
- size_t AlignedSize = alignTo(Size, Mapping.getAllocaAlignment());
+ size_t AlignedSize = alignTo(Size, Mapping.getObjectAlignment());
Value *JustTag = IRB.CreateTrunc(Tag, IRB.getInt8Ty());
if (ClInstrumentWithCalls) {
@@ -736,7 +756,7 @@ bool HWAddressSanitizer::tagAlloca(IRBuilder<> &IRB, AllocaInst *AI,
IRB.CreateMemSet(ShadowPtr, JustTag, ShadowSize, /*Align=*/1);
if (Size != AlignedSize) {
IRB.CreateStore(
- ConstantInt::get(Int8Ty, Size % Mapping.getAllocaAlignment()),
+ ConstantInt::get(Int8Ty, Size % Mapping.getObjectAlignment()),
IRB.CreateConstGEP1_32(Int8Ty, ShadowPtr, ShadowSize));
IRB.CreateStore(JustTag, IRB.CreateConstGEP1_32(
Int8Ty, IRB.CreateBitCast(AI, Int8PtrTy),
@@ -1018,7 +1038,7 @@ bool HWAddressSanitizer::instrumentStack(
// Re-tag alloca memory with the special UAR tag.
Value *Tag = getUARTag(IRB, StackTag);
- tagAlloca(IRB, AI, Tag, alignTo(Size, Mapping.getAllocaAlignment()));
+ tagAlloca(IRB, AI, Tag, alignTo(Size, Mapping.getObjectAlignment()));
}
}
@@ -1116,8 +1136,9 @@ bool HWAddressSanitizer::sanitizeFunction(Function &F) {
DenseMap<AllocaInst *, AllocaInst *> AllocaToPaddedAllocaMap;
for (AllocaInst *AI : AllocasToInstrument) {
uint64_t Size = getAllocaSizeInBytes(*AI);
- uint64_t AlignedSize = alignTo(Size, Mapping.getAllocaAlignment());
- AI->setAlignment(std::max(AI->getAlignment(), 16u));
+ uint64_t AlignedSize = alignTo(Size, Mapping.getObjectAlignment());
+ AI->setAlignment(
+ std::max(AI->getAlignment(), Mapping.getObjectAlignment()));
if (Size != AlignedSize) {
Type *AllocatedType = AI->getAllocatedType();
if (AI->isArrayAllocation()) {
@@ -1177,6 +1198,194 @@ bool HWAddressSanitizer::sanitizeFunction(Function &F) {
return Changed;
}
+void HWAddressSanitizer::instrumentGlobal(GlobalVariable *GV, uint8_t Tag) {
+ Constant *Initializer = GV->getInitializer();
+ uint64_t SizeInBytes =
+ M.getDataLayout().getTypeAllocSize(Initializer->getType());
+ uint64_t NewSize = alignTo(SizeInBytes, Mapping.getObjectAlignment());
+ if (SizeInBytes != NewSize) {
+ // Pad the initializer out to the next multiple of 16 bytes and add the
+ // required short granule tag.
+ std::vector<uint8_t> Init(NewSize - SizeInBytes, 0);
+ Init.back() = Tag;
+ Constant *Padding = ConstantDataArray::get(*C, Init);
+ Initializer = ConstantStruct::getAnon({Initializer, Padding});
+ }
+
+ auto *NewGV = new GlobalVariable(M, Initializer->getType(), GV->isConstant(),
+ GlobalValue::ExternalLinkage, Initializer,
+ GV->getName() + ".hwasan");
+ NewGV->copyAttributesFrom(GV);
+ NewGV->setLinkage(GlobalValue::PrivateLinkage);
+ NewGV->copyMetadata(GV, 0);
+ NewGV->setAlignment(
+ std::max(GV->getAlignment(), Mapping.getObjectAlignment()));
+
+ // It is invalid to ICF two globals that have different tags. In the case
+ // where the size of the global is a multiple of the tag granularity the
+ // contents of the globals may be the same but the tags (i.e. symbol values)
+ // may be different, and the symbols are not considered during ICF. In the
+ // case where the size is not a multiple of the granularity, the short granule
+ // tags would discriminate two globals with different tags, but there would
+ // otherwise be nothing stopping such a global from being incorrectly ICF'd
+ // with an uninstrumented (i.e. tag 0) global that happened to have the short
+ // granule tag in the last byte.
+ NewGV->setUnnamedAddr(GlobalValue::UnnamedAddr::None);
+
+ // Descriptor format (assuming little-endian):
+ // bytes 0-3: relative address of global
+ // bytes 4-6: size of global (16MB ought to be enough for anyone, but in case
+ // it isn't, we create multiple descriptors)
+ // byte 7: tag
+ auto *DescriptorTy = StructType::get(Int32Ty, Int32Ty);
+ const uint64_t MaxDescriptorSize = 0xfffff0;
+ for (uint64_t DescriptorPos = 0; DescriptorPos < SizeInBytes;
+ DescriptorPos += MaxDescriptorSize) {
+ auto *Descriptor =
+ new GlobalVariable(M, DescriptorTy, true, GlobalValue::PrivateLinkage,
+ nullptr, GV->getName() + ".hwasan.descriptor");
+ auto *GVRelPtr = ConstantExpr::getTrunc(
+ ConstantExpr::getAdd(
+ ConstantExpr::getSub(
+ ConstantExpr::getPtrToInt(NewGV, Int64Ty),
+ ConstantExpr::getPtrToInt(Descriptor, Int64Ty)),
+ ConstantInt::get(Int64Ty, DescriptorPos)),
+ Int32Ty);
+ uint32_t Size = std::min(SizeInBytes - DescriptorPos, MaxDescriptorSize);
+ auto *SizeAndTag = ConstantInt::get(Int32Ty, Size | (uint32_t(Tag) << 24));
+ Descriptor->setComdat(NewGV->getComdat());
+ Descriptor->setInitializer(ConstantStruct::getAnon({GVRelPtr, SizeAndTag}));
+ Descriptor->setSection("hwasan_globals");
+ Descriptor->setMetadata(LLVMContext::MD_associated,
+ MDNode::get(*C, ValueAsMetadata::get(NewGV)));
+ appendToCompilerUsed(M, Descriptor);
+ }
+
+ Constant *Aliasee = ConstantExpr::getIntToPtr(
+ ConstantExpr::getAdd(
+ ConstantExpr::getPtrToInt(NewGV, Int64Ty),
+ ConstantInt::get(Int64Ty, uint64_t(Tag) << kPointerTagShift)),
+ GV->getType());
+ auto *Alias = GlobalAlias::create(GV->getValueType(), GV->getAddressSpace(),
+ GV->getLinkage(), "", Aliasee, &M);
+ Alias->setVisibility(GV->getVisibility());
+ Alias->takeName(GV);
+ GV->replaceAllUsesWith(Alias);
+ GV->eraseFromParent();
+}
+
+void HWAddressSanitizer::instrumentGlobals() {
+ // Start by creating a note that contains pointers to the list of global
+ // descriptors. Adding a note to the output file will cause the linker to
+ // create a PT_NOTE program header pointing to the note that we can use to
+ // find the descriptor list starting from the program headers. A function
+ // provided by the runtime initializes the shadow memory for the globals by
+ // accessing the descriptor list via the note. The dynamic loader needs to
+ // call this function whenever a library is loaded.
+ //
+ // The reason why we use a note for this instead of a more conventional
+ // approach of having a global constructor pass a descriptor list pointer to
+ // the runtime is because of an order of initialization problem. With
+ // constructors we can encounter the following problematic scenario:
+ //
+ // 1) library A depends on library B and also interposes one of B's symbols
+ // 2) B's constructors are called before A's (as required for correctness)
+ // 3) during construction, B accesses one of its "own" globals (actually
+ // interposed by A) and triggers a HWASAN failure due to the initialization
+ // for A not having happened yet
+ //
+ // Even without interposition it is possible to run into similar situations in
+ // cases where two libraries mutually depend on each other.
+ //
+ // We only need one note per binary, so put everything for the note in a
+ // comdat.
+ Comdat *NoteComdat = M.getOrInsertComdat(kHwasanNoteName);
+
+ Type *Int8Arr0Ty = ArrayType::get(Int8Ty, 0);
+ auto Start =
+ new GlobalVariable(M, Int8Arr0Ty, true, GlobalVariable::ExternalLinkage,
+ nullptr, "__start_hwasan_globals");
+ Start->setVisibility(GlobalValue::HiddenVisibility);
+ Start->setDSOLocal(true);
+ auto Stop =
+ new GlobalVariable(M, Int8Arr0Ty, true, GlobalVariable::ExternalLinkage,
+ nullptr, "__stop_hwasan_globals");
+ Stop->setVisibility(GlobalValue::HiddenVisibility);
+ Stop->setDSOLocal(true);
+
+ // Null-terminated so actually 8 bytes, which are required in order to align
+ // the note properly.
+ auto *Name = ConstantDataArray::get(*C, "LLVM\0\0\0");
+
+ auto *NoteTy = StructType::get(Int32Ty, Int32Ty, Int32Ty, Name->getType(),
+ Int32Ty, Int32Ty);
+ auto *Note =
+ new GlobalVariable(M, NoteTy, /*isConstantGlobal=*/true,
+ GlobalValue::PrivateLinkage, nullptr, kHwasanNoteName);
+ Note->setSection(".note.hwasan.globals");
+ Note->setComdat(NoteComdat);
+ Note->setAlignment(4);
+ Note->setDSOLocal(true);
+
+ // The pointers in the note need to be relative so that the note ends up being
+ // placed in rodata, which is the standard location for notes.
+ auto CreateRelPtr = [&](Constant *Ptr) {
+ return ConstantExpr::getTrunc(
+ ConstantExpr::getSub(ConstantExpr::getPtrToInt(Ptr, Int64Ty),
+ ConstantExpr::getPtrToInt(Note, Int64Ty)),
+ Int32Ty);
+ };
+ Note->setInitializer(ConstantStruct::getAnon(
+ {ConstantInt::get(Int32Ty, 8), // n_namesz
+ ConstantInt::get(Int32Ty, 8), // n_descsz
+ ConstantInt::get(Int32Ty, ELF::NT_LLVM_HWASAN_GLOBALS), // n_type
+ Name, CreateRelPtr(Start), CreateRelPtr(Stop)}));
+ appendToCompilerUsed(M, Note);
+
+ // Create a zero-length global in hwasan_globals so that the linker will
+ // always create start and stop symbols.
+ auto Dummy = new GlobalVariable(
+ M, Int8Arr0Ty, /*isConstantGlobal*/ true, GlobalVariable::PrivateLinkage,
+ Constant::getNullValue(Int8Arr0Ty), "hwasan.dummy.global");
+ Dummy->setSection("hwasan_globals");
+ Dummy->setComdat(NoteComdat);
+ Dummy->setMetadata(LLVMContext::MD_associated,
+ MDNode::get(*C, ValueAsMetadata::get(Note)));
+ appendToCompilerUsed(M, Dummy);
+
+ std::vector<GlobalVariable *> Globals;
+ for (GlobalVariable &GV : M.globals()) {
+ if (GV.isDeclarationForLinker() || GV.getName().startswith("llvm.") ||
+ GV.isThreadLocal())
+ continue;
+
+ // Common symbols can't have aliases point to them, so they can't be tagged.
+ if (GV.hasCommonLinkage())
+ continue;
+
+ // Globals with custom sections may be used in __start_/__stop_ enumeration,
+ // which would be broken both by adding tags and potentially by the extra
+ // padding/alignment that we insert.
+ if (GV.hasSection())
+ continue;
+
+ Globals.push_back(&GV);
+ }
+
+ MD5 Hasher;
+ Hasher.update(M.getSourceFileName());
+ MD5::MD5Result Hash;
+ Hasher.final(Hash);
+ uint8_t Tag = Hash[0];
+
+ for (GlobalVariable *GV : Globals) {
+ // Skip tag 0 in order to avoid collisions with untagged memory.
+ if (Tag == 0)
+ Tag = 1;
+ instrumentGlobal(GV, Tag++);
+ }
+}
+
void HWAddressSanitizer::ShadowMapping::init(Triple &TargetTriple) {
Scale = kDefaultShadowScale;
if (ClMappingOffset.getNumOccurrences() > 0) {
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