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[DFSan] Handle landingpad inst explicitly as zero shadow. 

Before this change, DFSan was relying fallback cases when getting origin
address.

Differential Revision: https://reviews.llvm.org/D104266
This commit is contained in:
Andrew Browne 2021-06-14 13:41:24 -07:00
parent 4f194d0db7
commit af93157625
2 changed files with 18 additions and 1 deletions
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17
llvm/lib/Transforms/Instrumentation/DataFlowSanitizer.cpp
View File

@ -721,6 +721,7 @@ public:
void visitBitCastInst(BitCastInst &BCI);
void visitCastInst(CastInst &CI);
void visitCmpInst(CmpInst &CI);
void visitLandingPadInst(LandingPadInst &LPI);
void visitGetElementPtrInst(GetElementPtrInst &GEPI);
void visitLoadInst(LoadInst &LI);
void visitStoreInst(StoreInst &SI);
@ -2561,6 +2562,22 @@ void DFSanVisitor::visitCmpInst(CmpInst &CI) {
}
}
void DFSanVisitor::visitLandingPadInst(LandingPadInst &LPI) {
// We do not need to track data through LandingPadInst.
//
// For the C++ exceptions, if a value is thrown, this value will be stored
// in a memory location provided by __cxa_allocate_exception(...) (on the
// throw side) or __cxa_begin_catch(...) (on the catch side).
// This memory will have a shadow, so with the loads and stores we will be
// able to propagate labels on data thrown through exceptions, without any
// special handling of the LandingPadInst.
//
// The second element in the pair result of the LandingPadInst is a
// register value, but it is for a type ID and should never be tainted.
DFSF.setShadow(&LPI, DFSF.DFS.getZeroShadow(&LPI));
DFSF.setOrigin(&LPI, DFSF.DFS.ZeroOrigin);
}
void DFSanVisitor::visitGetElementPtrInst(GetElementPtrInst &GEPI) {
if (ClCombineOffsetLabelsOnGEP) {
visitInstOperands(GEPI);

2
llvm/test/Instrumentation/DataFlowSanitizer/call.ll
View File

@ -48,7 +48,7 @@ lpad:
catch i8* null
%1 = extractvalue { i8*, i32 } %0, 0
; CHECK: store {{.*}} @__dfsan_arg_tls
; CHECK: store i8 0,{{.*}} @__dfsan_arg_tls
; CHECK: call {{.*}} @"dfs$__cxa_begin_catch"
; CHECK: load {{.*}} @__dfsan_retval_tls
%2 = tail call i8* @__cxa_begin_catch(i8* %1)