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[msan] Unpoison stack allocations and undef values in blacklisted functions.

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This changes behavior of -msan-poison-stack=0 flag from not poisoning stack
allocations to actively unpoisoning them.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@185538 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Evgeniy Stepanov 2013-07-03 14:39:14 +00:00
parent bf8eb3d55c
commit d55ef5ce5f
2 changed files with 49 additions and 10 deletions
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24
lib/Transforms/Instrumentation/MemorySanitizer.cpp
View File

@ -425,6 +425,8 @@ struct MemorySanitizerVisitor : public InstVisitor<MemorySanitizerVisitor> {
ValueMap<Value*, Value*> ShadowMap, OriginMap;
bool InsertChecks;
bool LoadShadow;
bool PoisonStack;
bool PoisonUndef;
OwningPtr<VarArgHelper> VAHelper;
struct ShadowOriginAndInsertPoint {
@ -440,10 +442,13 @@ struct MemorySanitizerVisitor : public InstVisitor<MemorySanitizerVisitor> {
MemorySanitizerVisitor(Function &F, MemorySanitizer &MS)
: F(F), MS(MS), VAHelper(CreateVarArgHelper(F, MS, *this)) {
LoadShadow = InsertChecks =
!MS.BL->isIn(F) &&
F.getAttributes().hasAttribute(AttributeSet::FunctionIndex,
Attribute::SanitizeMemory);
bool SanitizeFunction = !MS.BL->isIn(F) && F.getAttributes().hasAttribute(
AttributeSet::FunctionIndex,
Attribute::SanitizeMemory);
InsertChecks = SanitizeFunction;
LoadShadow = SanitizeFunction;
PoisonStack = SanitizeFunction && ClPoisonStack;
PoisonUndef = SanitizeFunction && ClPoisonUndef;
DEBUG(if (!InsertChecks)
dbgs() << "MemorySanitizer is not inserting checks into '"
@ -744,7 +749,7 @@ struct MemorySanitizerVisitor : public InstVisitor<MemorySanitizerVisitor> {
return Shadow;
}
if (UndefValue *U = dyn_cast<UndefValue>(V)) {
Value *AllOnes = ClPoisonUndef ? getPoisonedShadow(V) : getCleanShadow(V);
Value *AllOnes = PoisonUndef ? getPoisonedShadow(V) : getCleanShadow(V);
DEBUG(dbgs() << "Undef: " << *U << " ==> " << *AllOnes << "\n");
(void)U;
return AllOnes;
@ -1704,20 +1709,19 @@ struct MemorySanitizerVisitor : public InstVisitor<MemorySanitizerVisitor> {
void visitAllocaInst(AllocaInst &I) {
setShadow(&I, getCleanShadow(&I));
if (!ClPoisonStack) return;
IRBuilder<> IRB(I.getNextNode());
uint64_t Size = MS.TD->getTypeAllocSize(I.getAllocatedType());
if (ClPoisonStackWithCall) {
if (PoisonStack && ClPoisonStackWithCall) {
IRB.CreateCall2(MS.MsanPoisonStackFn,
IRB.CreatePointerCast(&I, IRB.getInt8PtrTy()),
ConstantInt::get(MS.IntptrTy, Size));
} else {
Value *ShadowBase = getShadowPtr(&I, Type::getInt8PtrTy(*MS.C), IRB);
IRB.CreateMemSet(ShadowBase, IRB.getInt8(ClPoisonStackPattern),
Size, I.getAlignment());
Value *PoisonValue = IRB.getInt8(PoisonStack ? ClPoisonStackPattern : 0);
IRB.CreateMemSet(ShadowBase, PoisonValue, Size, I.getAlignment());
}
if (MS.TrackOrigins) {
if (PoisonStack && MS.TrackOrigins) {
setOrigin(&I, getCleanOrigin());
SmallString<2048> StackDescriptionStorage;
raw_svector_ostream StackDescription(StackDescriptionStorage);

35
test/Instrumentation/MemorySanitizer/msan_basic.ll
View File

@ -638,6 +638,41 @@ declare void @bar()
; CHECK: ret i32
; Test that stack allocations are unpoisoned in functions missing
; sanitize_memory attribute
define i32 @NoSanitizeMemoryAlloca() {
entry:
%p = alloca i32, align 4
%x = call i32 @NoSanitizeMemoryAllocaHelper(i32* %p)
ret i32 %x
}
declare i32 @NoSanitizeMemoryAllocaHelper(i32* %p)
; CHECK: @NoSanitizeMemoryAlloca
; CHECK: call void @llvm.memset.p0i8.i64(i8* {{.*}}, i8 0, i64 4, i32 4, i1 false)
; CHECK: call i32 @NoSanitizeMemoryAllocaHelper(i32*
; CHECK: ret i32
; Test that undef is unpoisoned in functions missing
; sanitize_memory attribute
define i32 @NoSanitizeMemoryUndef() {
entry:
%x = call i32 @NoSanitizeMemoryUndefHelper(i32 undef)
ret i32 %x
}
declare i32 @NoSanitizeMemoryUndefHelper(i32 %x)
; CHECK: @NoSanitizeMemoryAlloca
; CHECK: store i32 0, i32* {{.*}} @__msan_param_tls
; CHECK: call i32 @NoSanitizeMemoryUndefHelper(i32 undef)
; CHECK: ret i32
; Test argument shadow alignment
define <2 x i64> @ArgumentShadowAlignment(i64 %a, <2 x i64> %b) sanitize_memory {