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[dfsan] Abort at runtime on indirect calls to uninstrumented vararg functions. 

We currently have no infrastructure to support these correctly.

This is accomplished by generating a call to a runtime library function that
aborts at runtime in place of the regular wrapper for such functions. Direct
calls are rewritten in the usual way during traversal of the caller's IR.

We also remove the "split-stack" attribute from such wrappers, as the code
generator cannot currently handle split-stack vararg functions.

llvm-svn: 221360
This commit is contained in:
Peter Collingbourne 2014-11-05 17:21:00 +00:00
parent 9727e7865e
commit a1099840ff
2 changed files with 38 additions and 12 deletions
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43
llvm/lib/Transforms/Instrumentation/DataFlowSanitizer.cpp
View File

@ -234,12 +234,14 @@ class DataFlowSanitizer : public ModulePass {
FunctionType *DFSanUnimplementedFnTy;
FunctionType *DFSanSetLabelFnTy;
FunctionType *DFSanNonzeroLabelFnTy;
FunctionType *DFSanVarargWrapperFnTy;
Constant *DFSanUnionFn;
Constant *DFSanCheckedUnionFn;
Constant *DFSanUnionLoadFn;
Constant *DFSanUnimplementedFn;
Constant *DFSanSetLabelFn;
Constant *DFSanNonzeroLabelFn;
Constant *DFSanVarargWrapperFn;
MDNode *ColdCallWeights;
DFSanABIList ABIList;
DenseMap<Value *, Function *> UnwrappedFnMap;
@ -439,6 +441,8 @@ bool DataFlowSanitizer::doInitialization(Module &M) {
DFSanSetLabelArgs, /*isVarArg=*/false);
DFSanNonzeroLabelFnTy = FunctionType::get(
Type::getVoidTy(*Ctx), None, /*isVarArg=*/false);
DFSanVarargWrapperFnTy = FunctionType::get(
Type::getVoidTy(*Ctx), Type::getInt8PtrTy(*Ctx), /*isVarArg=*/false);
if (GetArgTLSPtr) {
Type *ArgTLSTy = ArrayType::get(ShadowTy, 64);
@ -518,15 +522,26 @@ DataFlowSanitizer::buildWrapperFunction(Function *F, StringRef NewFName,
AttributeSet::ReturnIndex));
BasicBlock *BB = BasicBlock::Create(*Ctx, "entry", NewF);
std::vector<Value *> Args;
unsigned n = FT->getNumParams();
for (Function::arg_iterator ai = NewF->arg_begin(); n != 0; ++ai, --n)
Args.push_back(&*ai);
CallInst *CI = CallInst::Create(F, Args, "", BB);
if (FT->getReturnType()->isVoidTy())
ReturnInst::Create(*Ctx, BB);
else
ReturnInst::Create(*Ctx, CI, BB);
if (F->isVarArg()) {
NewF->removeAttributes(
AttributeSet::FunctionIndex,
AttributeSet().addAttribute(*Ctx, AttributeSet::FunctionIndex,
"split-stack"));
CallInst::Create(DFSanVarargWrapperFn,
IRBuilder<>(BB).CreateGlobalStringPtr(F->getName()), "",
BB);
new UnreachableInst(*Ctx, BB);
} else {
std::vector<Value *> Args;
unsigned n = FT->getNumParams();
for (Function::arg_iterator ai = NewF->arg_begin(); n != 0; ++ai, --n)
Args.push_back(&*ai);
CallInst *CI = CallInst::Create(F, Args, "", BB);
if (FT->getReturnType()->isVoidTy())
ReturnInst::Create(*Ctx, BB);
else
ReturnInst::Create(*Ctx, CI, BB);
}
return NewF;
}
@ -617,6 +632,8 @@ bool DataFlowSanitizer::runOnModule(Module &M) {
}
DFSanNonzeroLabelFn =
Mod->getOrInsertFunction("__dfsan_nonzero_label", DFSanNonzeroLabelFnTy);
DFSanVarargWrapperFn = Mod->getOrInsertFunction("__dfsan_vararg_wrapper",
DFSanVarargWrapperFnTy);
std::vector<Function *> FnsToInstrument;
llvm::SmallPtrSet<Function *, 2> FnsWithNativeABI;
@ -627,7 +644,8 @@ bool DataFlowSanitizer::runOnModule(Module &M) {
i != DFSanUnionLoadFn &&
i != DFSanUnimplementedFn &&
i != DFSanSetLabelFn &&
i != DFSanNonzeroLabelFn)
i != DFSanNonzeroLabelFn &&
i != DFSanVarargWrapperFn)
FnsToInstrument.push_back(&*i);
}
@ -1363,6 +1381,11 @@ void DFSanVisitor::visitCallSite(CallSite CS) {
return;
}
// Calls to this function are synthesized in wrappers, and we shouldn't
// instrument them.
if (F == DFSF.DFS.DFSanVarargWrapperFn)
return;
assert(!(cast<FunctionType>(
CS.getCalledValue()->getType()->getPointerElementType())->isVarArg() &&
dyn_cast<InvokeInst>(CS.getInstruction())));

7
llvm/test/Instrumentation/DataFlowSanitizer/abilist.ll
View File

@ -29,6 +29,9 @@ declare void @custom1(i32 %a, i32 %b)
; CHECK: ret { i32, i16 }
declare i32 @custom2(i32 %a, i32 %b)
; CHECK: define linkonce_odr void @"dfsw$custom3"(i32, i16, i16*, ...)
; CHECK: call void @__dfsan_vararg_wrapper(i8*
; CHECK: unreachable
declare void @custom3(i32 %a, ...)
declare i32 @custom4(i32 %a, ...)
@ -83,8 +86,6 @@ define i32 (i32, i32)* @g(i32) {
; CHECK: declare void @__dfsw_custom1(i32, i32, i16, i16)
; CHECK: declare i32 @__dfsw_custom2(i32, i32, i16, i16, i16*)
; CHECK: declare void @__dfsw_custom3(i32, i16, i16*, ...)
; CHECK: declare i32 @__dfsw_custom4(i32, i16, i16*, i16*, ...)
; CHECK-LABEL: define linkonce_odr i32 @"dfst0$customcb"(i32 (i32)*, i32, i16, i16*)
; CHECK: %[[BC:.*]] = bitcast i32 (i32)* %0 to { i32, i16 } (i32, i16)*
@ -94,3 +95,5 @@ define i32 (i32, i32)* @g(i32) {
; CHECK: store i16 %[[XVAL1]], i16* %3
; CHECK: ret i32 %[[XVAL0]]
; CHECK: declare void @__dfsw_custom3(i32, i16, i16*, ...)
; CHECK: declare i32 @__dfsw_custom4(i32, i16, i16*, i16*, ...)