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DataFlowSanitizer: Prefix the name of each instrumented function with "dfs$".

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DFSan changes the ABI of each function in the module.  This makes it possible
for a function with the native ABI to be called with the instrumented ABI,
or vice versa, thus possibly invoking undefined behavior.  A simple way
of statically detecting instances of this problem is to prepend the prefix
"dfs$" to the name of each instrumented-ABI function.

This will not catch every such problem; in particular function pointers passed
across the instrumented-native barrier cannot be used on the other side.
These problems could potentially be caught dynamically.

Differential Revision: http://llvm-reviews.chandlerc.com/D1373

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@189052 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Peter Collingbourne
2013-08-22 20:08:08 +00:00
parent 094637408b
commit f1366c5524
10 changed files with 87 additions and 29 deletions
Download Patch File Download Diff File Expand all files Collapse all files

58
lib/Transforms/Instrumentation/DataFlowSanitizer.cpp
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@@ -179,11 +179,13 @@ class DataFlowSanitizer : public ModulePass {
Value *getShadowAddress(Value *Addr, Instruction *Pos);
Value *combineShadows(Value *V1, Value *V2, Instruction *Pos);
bool isInstrumented(Function *F);
bool isInstrumented(const Function *F);
bool isInstrumented(const GlobalAlias *GA);
FunctionType *getArgsFunctionType(FunctionType *T);
FunctionType *getCustomFunctionType(FunctionType *T);
InstrumentedABI getInstrumentedABI();
WrapperKind getWrapperKind(Function *F);
void addGlobalNamePrefix(GlobalValue *GV);
public:
DataFlowSanitizer(StringRef ABIListFile = StringRef(),
@@ -343,10 +345,14 @@ bool DataFlowSanitizer::doInitialization(Module &M) {
return true;
}
bool DataFlowSanitizer::isInstrumented(Function *F) {
bool DataFlowSanitizer::isInstrumented(const Function *F) {
return !ABIList->isIn(*F, "uninstrumented");
}
bool DataFlowSanitizer::isInstrumented(const GlobalAlias *GA) {
return !ABIList->isIn(*GA, "uninstrumented");
}
DataFlowSanitizer::InstrumentedABI DataFlowSanitizer::getInstrumentedABI() {
return ClArgsABI ? IA_Args : IA_TLS;
}
@@ -362,6 +368,25 @@ DataFlowSanitizer::WrapperKind DataFlowSanitizer::getWrapperKind(Function *F) {
return WK_Warning;
}
void DataFlowSanitizer::addGlobalNamePrefix(GlobalValue *GV) {
std::string GVName = GV->getName(), Prefix = "dfs$";
GV->setName(Prefix + GVName);
// Try to change the name of the function in module inline asm. We only do
// this for specific asm directives, currently only ".symver", to try to avoid
// corrupting asm which happens to contain the symbol name as a substring.
// Note that the substitution for .symver assumes that the versioned symbol
// also has an instrumented name.
std::string Asm = GV->getParent()->getModuleInlineAsm();
std::string SearchStr = ".symver " + GVName + ",";
size_t Pos = Asm.find(SearchStr);
if (Pos != std::string::npos) {
Asm.replace(Pos, SearchStr.size(),
".symver " + Prefix + GVName + "," + Prefix);
GV->getParent()->setModuleInlineAsm(Asm);
}
}
bool DataFlowSanitizer::runOnModule(Module &M) {
if (!DL)
return false;
@@ -415,6 +440,21 @@ bool DataFlowSanitizer::runOnModule(Module &M) {
FnsToInstrument.push_back(&*i);
}
// Give function aliases prefixes when necessary.
for (Module::alias_iterator i = M.alias_begin(), e = M.alias_end(); i != e;) {
GlobalAlias *GA = &*i;
++i;
// Don't stop on weak. We assume people aren't playing games with the
// instrumentedness of overridden weak aliases.
if (Function *F = dyn_cast<Function>(
GA->resolveAliasedGlobal(/*stopOnWeak=*/false))) {
bool GAInst = isInstrumented(GA), FInst = isInstrumented(F);
if (GAInst && FInst) {
addGlobalNamePrefix(GA);
}
}
}
AttrBuilder B;
B.addAttribute(Attribute::ReadOnly).addAttribute(Attribute::ReadNone);
ReadOnlyNoneAttrs = AttributeSet::get(*Ctx, AttributeSet::FunctionIndex, B);
@@ -427,12 +467,13 @@ bool DataFlowSanitizer::runOnModule(Module &M) {
Function &F = **i;
FunctionType *FT = F.getFunctionType();
if (FT->getNumParams() == 0 && !FT->isVarArg() &&
FT->getReturnType()->isVoidTy())
continue;
bool IsZeroArgsVoidRet = (FT->getNumParams() == 0 && !FT->isVarArg() &&
FT->getReturnType()->isVoidTy());
if (isInstrumented(&F)) {
if (getInstrumentedABI() == IA_Args) {
// Instrumented functions get a 'dfs$' prefix. This allows us to more
// easily identify cases of mismatching ABIs.
if (getInstrumentedABI() == IA_Args && !IsZeroArgsVoidRet) {
FunctionType *NewFT = getArgsFunctionType(FT);
Function *NewF = Function::Create(NewFT, F.getLinkage(), "", &M);
NewF->copyAttributesFrom(&F);
@@ -463,13 +504,16 @@ bool DataFlowSanitizer::runOnModule(Module &M) {
NewF->takeName(&F);
F.eraseFromParent();
*i = NewF;
addGlobalNamePrefix(NewF);
} else {
addGlobalNamePrefix(&F);
}
// Hopefully, nobody will try to indirectly call a vararg
// function... yet.
} else if (FT->isVarArg()) {
UnwrappedFnMap[&F] = &F;
*i = 0;
} else {
} else if (!IsZeroArgsVoidRet || getWrapperKind(&F) == WK_Custom) {
// Build a wrapper function for F. The wrapper simply calls F, and is
// added to FnsToInstrument so that any instrumentation according to its
// WrapperKind is done in the second pass below.