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Be more careful in parsing Module::ModFlagBehavior value

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to make sure we don't do invalid load of an enum. Share the
conversion code between llvm::Module implementation and the
verifier.

This bug was reported by UBSan.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@217395 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Alexey Samsonov
2014-09-08 19:16:28 +00:00
parent 16ee570cc3
commit e769dc39fd
3 changed files with 36 additions and 18 deletions
Download Patch File Download Diff File Expand all files Collapse all files
lib/IR/Module.cpp
+15 -4
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@@ -259,6 +259,17 @@ void Module::eraseNamedMetadata(NamedMDNode *NMD) {
NamedMDList.erase(NMD);
}
bool Module::isValidModFlagBehavior(Value *V, ModFlagBehavior &MFB) {
if (ConstantInt *Behavior = dyn_cast<ConstantInt>(V)) {
uint64_t Val = Behavior->getLimitedValue();
if (Val >= ModFlagBehaviorFirstVal && Val <= ModFlagBehaviorLastVal) {
MFB = static_cast<ModFlagBehavior>(Val);
return true;
}
}
return false;
}
/// getModuleFlagsMetadata - Returns the module flags in the provided vector.
void Module::
getModuleFlagsMetadata(SmallVectorImpl<ModuleFlagEntry> &Flags) const {
@@ -266,15 +277,15 @@ getModuleFlagsMetadata(SmallVectorImpl<ModuleFlagEntry> &Flags) const {
if (!ModFlags) return;
for (const MDNode *Flag : ModFlags->operands()) {
if (Flag->getNumOperands() >= 3 && isa<ConstantInt>(Flag->getOperand(0)) &&
ModFlagBehavior MFB;
if (Flag->getNumOperands() >= 3 &&
isValidModFlagBehavior(Flag->getOperand(0), MFB) &&
isa<MDString>(Flag->getOperand(1))) {
// Check the operands of the MDNode before accessing the operands.
// The verifier will actually catch these failures.
ConstantInt *Behavior = cast<ConstantInt>(Flag->getOperand(0));
MDString *Key = cast<MDString>(Flag->getOperand(1));
Value *Val = Flag->getOperand(2);
Flags.push_back(ModuleFlagEntry(ModFlagBehavior(Behavior->getZExtValue()),
Key, Val));
Flags.push_back(ModuleFlagEntry(MFB, Key, Val));
}
}
}