call __asan_load_cxx_array_cookie when loading array cookie in asan mode.
Summary:
The current implementation of asan cookie is incorrect:
we add nosanitize metadata to the cookie load, but the metadata may be lost
and we will instrument the load from poisoned memory.
This change replaces the load with a call to __asan_load_cxx_array_cookie (r216692)
Reviewers: rsmith
Reviewed By: rsmith
Subscribers: cfe-commits
Differential Revision: http://reviews.llvm.org/D5111
llvm-svn: 216702
diff --git a/clang/lib/CodeGen/ItaniumCXXABI.cpp b/clang/lib/CodeGen/ItaniumCXXABI.cpp
index 5df3e43..f861af3 100644
--- a/clang/lib/CodeGen/ItaniumCXXABI.cpp
+++ b/clang/lib/CodeGen/ItaniumCXXABI.cpp
@@ -1476,8 +1476,9 @@
llvm::Value *NumElementsPtr =
CGF.Builder.CreateBitCast(CookiePtr, NumElementsTy);
llvm::Instruction *SI = CGF.Builder.CreateStore(NumElements, NumElementsPtr);
- if (CGM.getLangOpts().Sanitize.Address &&
+ if (CGM.getLangOpts().Sanitize.Address && AS == 0 &&
expr->getOperatorNew()->isReplaceableGlobalAllocationFunction()) {
+ // The store to the CookiePtr does not need to be instrumented.
CGM.getSanitizerMetadata()->disableSanitizerForInstruction(SI);
llvm::FunctionType *FTy =
llvm::FunctionType::get(CGM.VoidTy, NumElementsTy, false);
@@ -1507,10 +1508,18 @@
unsigned AS = allocPtr->getType()->getPointerAddressSpace();
numElementsPtr =
CGF.Builder.CreateBitCast(numElementsPtr, CGF.SizeTy->getPointerTo(AS));
- llvm::Instruction *LI = CGF.Builder.CreateLoad(numElementsPtr);
- if (CGM.getLangOpts().Sanitize.Address)
- CGM.getSanitizerMetadata()->disableSanitizerForInstruction(LI);
- return LI;
+ if (!CGM.getLangOpts().Sanitize.Address || AS != 0)
+ return CGF.Builder.CreateLoad(numElementsPtr);
+ // In asan mode emit a function call instead of a regular load and let the
+ // run-time deal with it: if the shadow is properly poisoned return the
+ // cookie, otherwise return 0 to avoid an infinite loop calling DTORs.
+ // We can't simply ignore this load using nosanitize metadata because
+ // the metadata may be lost.
+ llvm::FunctionType *FTy =
+ llvm::FunctionType::get(CGF.SizeTy, CGF.SizeTy->getPointerTo(0), false);
+ llvm::Constant *F =
+ CGM.CreateRuntimeFunction(FTy, "__asan_load_cxx_array_cookie");
+ return CGF.Builder.CreateCall(F, numElementsPtr);
}
CharUnits ARMCXXABI::getArrayCookieSizeImpl(QualType elementType) {