[cfi] Safe handling of unaddressable vtable pointers (clang).
Avoid crashing when printing diagnostics for vtable-related CFI
errors. In diagnostic mode, the frontend does an additional check of
the vtable pointer against the set of all known vtable addresses and
lets the runtime handler know if it is safe to inspect the vtable.
http://reviews.llvm.org/D16823
llvm-svn: 259716
diff --git a/clang/lib/CodeGen/CGExpr.cpp b/clang/lib/CodeGen/CGExpr.cpp
index 10547a4..0855b45 100644
--- a/clang/lib/CodeGen/CGExpr.cpp
+++ b/clang/lib/CodeGen/CGExpr.cpp
@@ -2636,6 +2636,14 @@
Address CheckKindAddr(V, getIntAlign());
llvm::Value *CheckKind = Builder.CreateLoad(CheckKindAddr);
+ llvm::Value *AllVtables = llvm::MetadataAsValue::get(
+ CGM.getLLVMContext(),
+ llvm::MDString::get(CGM.getLLVMContext(), "all-vtables"));
+ llvm::Value *ValidVtable = Builder.CreateZExt(
+ Builder.CreateCall(CGM.getIntrinsic(llvm::Intrinsic::bitset_test),
+ {Addr, AllVtables}),
+ IntPtrTy);
+
const std::pair<int, SanitizerMask> CheckKinds[] = {
{CFITCK_VCall, SanitizerKind::CFIVCall},
{CFITCK_NVCall, SanitizerKind::CFINVCall},
@@ -2649,7 +2657,8 @@
SanitizerMask Mask = CheckKindMaskPair.second;
llvm::Value *Cond =
Builder.CreateICmpNE(CheckKind, llvm::ConstantInt::get(Int8Ty, Kind));
- EmitCheck(std::make_pair(Cond, Mask), "cfi_check_fail", {}, {Data, Addr});
+ EmitCheck(std::make_pair(Cond, Mask), "cfi_check_fail", {},
+ {Data, Addr, ValidVtable});
}
FinishFunction();
@@ -3970,7 +3979,8 @@
CastedCallee, StaticData);
} else {
EmitCheck(std::make_pair(BitSetTest, SanitizerKind::CFIICall),
- "cfi_check_fail", StaticData, CastedCallee);
+ "cfi_check_fail", StaticData,
+ {CastedCallee, llvm::UndefValue::get(IntPtrTy)});
}
}