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[hwasan] Use stack safety analysis.

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This avoids unnecessary instrumentation.

Reviewed By: eugenis, vitalybuka

Differential Revision: https://reviews.llvm.org/D105703
This commit is contained in:
Florian Mayer 2021-07-22 14:19:21 -07:00 committed by Vitaly Buka
parent be583be23b
commit 96c63492cb
5 changed files with 137 additions and 18 deletions
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17
clang/lib/CodeGen/BackendUtil.cpp
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@ -314,14 +314,19 @@ static void addHWAddressSanitizerPasses(const PassManagerBuilder &Builder,
static_cast<const PassManagerBuilderWrapper &>(Builder);
const CodeGenOptions &CGOpts = BuilderWrapper.getCGOpts();
bool Recover = CGOpts.SanitizeRecover.has(SanitizerKind::HWAddress);
PM.add(
createHWAddressSanitizerLegacyPassPass(/*CompileKernel*/ false, Recover));
PM.add(createHWAddressSanitizerLegacyPassPass(
/*CompileKernel*/ false, Recover,
/*DisableOptimization*/ CGOpts.OptimizationLevel == 0));
}
static void addKernelHWAddressSanitizerPasses(const PassManagerBuilder &Builder,
legacy::PassManagerBase &PM) {
legacy::PassManagerBase &PM) {
const PassManagerBuilderWrapper &BuilderWrapper =
static_cast<const PassManagerBuilderWrapper &>(Builder);
const CodeGenOptions &CGOpts = BuilderWrapper.getCGOpts();
PM.add(createHWAddressSanitizerLegacyPassPass(
/*CompileKernel*/ true, /*Recover*/ true));
/*CompileKernel*/ true, /*Recover*/ true,
/*DisableOptimization*/ CGOpts.OptimizationLevel == 0));
}
static void addGeneralOptsForMemorySanitizer(const PassManagerBuilder &Builder,
@ -1164,7 +1169,9 @@ static void addSanitizers(const Triple &TargetTriple,
auto HWASanPass = [&](SanitizerMask Mask, bool CompileKernel) {
if (LangOpts.Sanitize.has(Mask)) {
bool Recover = CodeGenOpts.SanitizeRecover.has(Mask);
MPM.addPass(HWAddressSanitizerPass(CompileKernel, Recover));
MPM.addPass(HWAddressSanitizerPass(
CompileKernel, Recover,
/*DisableOptimization=*/CodeGenOpts.OptimizationLevel == 0));
}
};
HWASanPass(SanitizerKind::HWAddress, false);

15
clang/test/CodeGen/hwasan-stack-safety-analysis.c Normal file
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@ -0,0 +1,15 @@
// RUN: %clang -fsanitize=hwaddress -target aarch64-linux-gnu -S -emit-llvm -mllvm -hwasan-use-stack-safety=true -mllvm -hwasan-generate-tags-with-calls -O2 %s -o - | FileCheck %s --check-prefix=SAFETY
// RUN: %clang -fsanitize=hwaddress -target aarch64-linux-gnu -S -emit-llvm -mllvm -hwasan-use-stack-safety=false -mllvm -hwasan-generate-tags-with-calls -O2 %s -o - | FileCheck %s --check-prefix=NOSAFETY
// Default when optimizing, but not with O0.
// RUN: %clang -fsanitize=hwaddress -target aarch64-linux-gnu -S -emit-llvm -mllvm -hwasan-generate-tags-with-calls -O2 %s -o - | FileCheck %s --check-prefix=SAFETY
// RUN: %clang -fsanitize=hwaddress -target aarch64-linux-gnu -S -emit-llvm -mllvm -hwasan-generate-tags-with-calls -O0 %s -o - | FileCheck %s --check-prefix=NOSAFETY
int main(int argc, char **argv) {
char buf[10];
volatile char *x = buf;
*x = 0;
return buf[0];
// NOSAFETY: __hwasan_generate_tag
// SAFETY-NOT: __hwasan_generate_tag
}

10
llvm/include/llvm/Transforms/Instrumentation/HWAddressSanitizer.h
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@ -25,17 +25,21 @@ namespace llvm {
class HWAddressSanitizerPass : public PassInfoMixin<HWAddressSanitizerPass> {
public:
explicit HWAddressSanitizerPass(bool CompileKernel = false,
bool Recover = false);
bool Recover = false,
bool DisableOptimization = false);
PreservedAnalyses run(Module &M, ModuleAnalysisManager &MAM);
static bool isRequired() { return true; }
private:
bool CompileKernel;
bool Recover;
bool DisableOptimization;
};
FunctionPass *createHWAddressSanitizerLegacyPassPass(bool CompileKernel = false,
bool Recover = false);
FunctionPass *
createHWAddressSanitizerLegacyPassPass(bool CompileKernel = false,
bool Recover = false,
bool DisableOptimization = false);
namespace HWASanAccessInfo {

71
llvm/lib/Transforms/Instrumentation/HWAddressSanitizer.cpp
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@ -17,6 +17,7 @@
#include "llvm/ADT/StringExtras.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/ADT/Triple.h"
#include "llvm/Analysis/StackSafetyAnalysis.h"
#include "llvm/BinaryFormat/ELF.h"
#include "llvm/IR/Attributes.h"
#include "llvm/IR/BasicBlock.h"
@ -109,6 +110,11 @@ static cl::opt<bool> ClInstrumentStack("hwasan-instrument-stack",
cl::desc("instrument stack (allocas)"),
cl::Hidden, cl::init(true));
static cl::opt<bool>
ClUseStackSafety("hwasan-use-stack-safety", cl::Hidden, cl::init(true),
cl::Hidden, cl::desc("Use Stack Safety analysis results"),
cl::Optional);
static cl::opt<bool> ClUARRetagToZero(
"hwasan-uar-retag-to-zero",
cl::desc("Clear alloca tags before returning from the function to allow "
@ -204,11 +210,23 @@ bool shouldInstrumentWithCalls(const Triple &TargetTriple) {
return ClInstrumentWithCalls || TargetTriple.getArch() == Triple::x86_64;
}
bool mightUseStackSafetyAnalysis(bool DisableOptimization) {
return ClUseStackSafety.getNumOccurrences() ? ClUseStackSafety
: !DisableOptimization;
}
bool shouldUseStackSafetyAnalysis(const Triple &TargetTriple,
bool DisableOptimization) {
return shouldInstrumentStack(TargetTriple) &&
mightUseStackSafetyAnalysis(DisableOptimization);
}
/// An instrumentation pass implementing detection of addressability bugs
/// using tagged pointers.
class HWAddressSanitizer {
public:
HWAddressSanitizer(Module &M, bool CompileKernel, bool Recover) : M(M) {
HWAddressSanitizer(Module &M, bool CompileKernel, bool Recover,
const StackSafetyGlobalInfo *SSI)
: M(M), SSI(SSI) {
this->Recover = ClRecover.getNumOccurrences() > 0 ? ClRecover : Recover;
this->CompileKernel = ClEnableKhwasan.getNumOccurrences() > 0
? ClEnableKhwasan
@ -217,6 +235,8 @@ public:
initializeModule();
}
void setSSI(const StackSafetyGlobalInfo *S) { SSI = S; }
bool sanitizeFunction(Function &F);
void initializeModule();
void createHwasanCtorComdat();
@ -269,6 +289,7 @@ public:
private:
LLVMContext *C;
Module &M;
const StackSafetyGlobalInfo *SSI;
Triple TargetTriple;
FunctionCallee HWAsanMemmove, HWAsanMemcpy, HWAsanMemset;
FunctionCallee HWAsanHandleVfork;
@ -339,7 +360,8 @@ public:
static char ID;
explicit HWAddressSanitizerLegacyPass(bool CompileKernel = false,
bool Recover = false)
bool Recover = false,
bool DisableOptimization = false)
: FunctionPass(ID), CompileKernel(CompileKernel), Recover(Recover) {
initializeHWAddressSanitizerLegacyPassPass(
*PassRegistry::getPassRegistry());
@ -348,11 +370,19 @@ public:
StringRef getPassName() const override { return "HWAddressSanitizer"; }
bool doInitialization(Module &M) override {
HWASan = std::make_unique<HWAddressSanitizer>(M, CompileKernel, Recover);
HWASan = std::make_unique<HWAddressSanitizer>(M, CompileKernel, Recover,
/*SSI=*/nullptr);
return true;
}
bool runOnFunction(Function &F) override {
if (shouldUseStackSafetyAnalysis(Triple(F.getParent()->getTargetTriple()),
DisableOptimization)) {
// We cannot call getAnalysis in doInitialization, that would cause a
// crash as the required analyses are not initialized yet.
HWASan->setSSI(
&getAnalysis<StackSafetyGlobalInfoWrapperPass>().getResult());
}
return HWASan->sanitizeFunction(F);
}
@ -361,10 +391,20 @@ public:
return false;
}
void getAnalysisUsage(AnalysisUsage &AU) const override {
// This is an over-estimation of, in case we are building for an
// architecture that doesn't allow stack tagging we will still load the
// analysis.
// This is so we don't need to plumb TargetTriple all the way to here.
if (mightUseStackSafetyAnalysis(DisableOptimization))
AU.addRequired<StackSafetyGlobalInfoWrapperPass>();
}
private:
std::unique_ptr<HWAddressSanitizer> HWASan;
bool CompileKernel;
bool Recover;
bool DisableOptimization;
};
} // end anonymous namespace
@ -375,23 +415,32 @@ INITIALIZE_PASS_BEGIN(
HWAddressSanitizerLegacyPass, "hwasan",
"HWAddressSanitizer: detect memory bugs using tagged addressing.", false,
false)
INITIALIZE_PASS_DEPENDENCY(StackSafetyGlobalInfoWrapperPass)
INITIALIZE_PASS_END(
HWAddressSanitizerLegacyPass, "hwasan",
"HWAddressSanitizer: detect memory bugs using tagged addressing.", false,
false)
FunctionPass *llvm::createHWAddressSanitizerLegacyPassPass(bool CompileKernel,
bool Recover) {
FunctionPass *
llvm::createHWAddressSanitizerLegacyPassPass(bool CompileKernel, bool Recover,
bool DisableOptimization) {
assert(!CompileKernel || Recover);
return new HWAddressSanitizerLegacyPass(CompileKernel, Recover);
return new HWAddressSanitizerLegacyPass(CompileKernel, Recover,
DisableOptimization);
}
HWAddressSanitizerPass::HWAddressSanitizerPass(bool CompileKernel, bool Recover)
: CompileKernel(CompileKernel), Recover(Recover) {}
HWAddressSanitizerPass::HWAddressSanitizerPass(bool CompileKernel, bool Recover,
bool DisableOptimization)
: CompileKernel(CompileKernel), Recover(Recover),
DisableOptimization(DisableOptimization) {}
PreservedAnalyses HWAddressSanitizerPass::run(Module &M,
ModuleAnalysisManager &MAM) {
HWAddressSanitizer HWASan(M, CompileKernel, Recover);
const StackSafetyGlobalInfo *SSI = nullptr;
if (shouldUseStackSafetyAnalysis(llvm::Triple(M.getTargetTriple()),
DisableOptimization))
SSI = &MAM.getResult<StackSafetyGlobalAnalysis>(M);
HWAddressSanitizer HWASan(M, CompileKernel, Recover, SSI);
bool Modified = false;
for (Function &F : M)
Modified |= HWASan.sanitizeFunction(F);
@ -1245,7 +1294,9 @@ bool HWAddressSanitizer::isInterestingAlloca(const AllocaInst &AI) {
// dynamic alloca instrumentation for them as well.
!AI.isUsedWithInAlloca() &&
// swifterror allocas are register promoted by ISel
!AI.isSwiftError());
!AI.isSwiftError()) &&
// safe allocas are not interesting
!(SSI && SSI->isSafe(AI));
}
bool HWAddressSanitizer::sanitizeFunction(Function &F) {

42
llvm/test/Instrumentation/HWAddressSanitizer/stack-safety-analysis.ll Normal file
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@ -0,0 +1,42 @@
; RUN: opt -hwasan -hwasan-use-stack-safety=1 -hwasan-generate-tags-with-calls -S < %s | FileCheck %s --check-prefixes=SAFETY
; RUN: opt -hwasan -hwasan-use-stack-safety=0 -hwasan-generate-tags-with-calls -S < %s | FileCheck %s --check-prefixes=NOSAFETY
target datalayout = "e-m:e-i8:8:32-i16:16:32-i64:64-i128:128-n32:64-S128"
target triple = "aarch64-unknown-linux-gnu"
; Check a safe alloca to ensure it does not get a tag.
define i32 @test_load(i32* %a) sanitize_hwaddress {
entry:
; NOSAFETY: call {{.*}}__hwasan_generate_tag
; SAFETY-NOT: call {{.*}}__hwasan_generate_tag
%buf.sroa.0 = alloca i8, align 4
call void @llvm.lifetime.start.p0i8(i64 1, i8* nonnull %buf.sroa.0)
store volatile i8 0, i8* %buf.sroa.0, align 4, !tbaa !8
call void @llvm.lifetime.end.p0i8(i64 1, i8* nonnull %buf.sroa.0)
ret i32 0
}
; Check a non-safe alloca to ensure it gets a tag.
define i32 @test_use(i32* %a) sanitize_hwaddress {
entry:
; NOSAFETY: call {{.*}}__hwasan_generate_tag
; SAFETY: call {{.*}}__hwasan_generate_tag
%buf.sroa.0 = alloca i8, align 4
call void @use(i8* nonnull %buf.sroa.0)
call void @llvm.lifetime.start.p0i8(i64 1, i8* nonnull %buf.sroa.0)
store volatile i8 0, i8* %buf.sroa.0, align 4, !tbaa !8
call void @llvm.lifetime.end.p0i8(i64 1, i8* nonnull %buf.sroa.0)
ret i32 0
}
; Function Attrs: argmemonly mustprogress nofree nosync nounwind willreturn
declare void @llvm.lifetime.start.p0i8(i64 immarg, i8* nocapture)
; Function Attrs: argmemonly mustprogress nofree nosync nounwind willreturn
declare void @llvm.lifetime.end.p0i8(i64 immarg, i8* nocapture)
declare void @use(i8* nocapture)
!8 = !{!9, !9, i64 0}
!9 = !{!"omnipotent char", !10, i64 0}
!10 = !{!"Simple C/C++ TBAA"}