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Implement the callback that warns the user on null ptr deref.

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This commit is contained in:
Baozeng Ding 2013-07-18 14:23:48 +03:00 committed by sftnight
parent 80d57d9c93
commit 9ee3398603
1 changed files with 41 additions and 3 deletions
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44
lib/Interpreter/NullDerefProtectionTransformer.cpp
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@ -19,6 +19,19 @@
#include "llvm/Support/raw_ostream.h"
#include "llvm/Support/InstIterator.h"
extern "C" {
int printf(const char *...);
int getchar(void);
bool shouldProceed() {
int input;
printf("Warning: you are about to dereference null ptr, which probably will lead to seg violation. Do you want to proceed?[y/n]\n");
input = getchar();
getchar();
if (input == 'y' || input == 'Y') return false;
else return true;
}
}
namespace cling {
NullDerefProtectionTransformer::NullDerefProtectionTransformer()
@ -74,18 +87,40 @@ namespace cling {
}
llvm::BasicBlock* NullDerefProtectionTransformer::getTrapBB() {
llvm::Function *Fn = Inst->getParent()->getParent();
llvm::Module *Md = Fn->getParent();
llvm::LLVMContext& ctx = Fn->getContext();
llvm::BasicBlock::iterator PreInsertInst = Builder->GetInsertPoint();
FailBB = llvm::BasicBlock::Create(ctx, "FailBlock", Fn);
llvm::ReturnInst::Create(Fn->getContext(), FailBB);
Builder->SetInsertPoint(FailBB);
llvm::FunctionType* FTy = llvm::FunctionType::get(llvm::Type::getInt1Ty(ctx), false);
llvm::Function *CallBackFn
= llvm::cast<llvm::Function>(Md->getOrInsertFunction("shouldProceed", FTy));
llvm::CallInst *CI = Builder->CreateCall(CallBackFn);
llvm::Value *TrueVl = llvm::ConstantInt::get(ctx, llvm::APInt(1, 1));
llvm::Value *RetVl = CI;
llvm::ICmpInst *Cmp
= new llvm::ICmpInst(*FailBB, llvm::CmpInst::ICMP_EQ, RetVl,
TrueVl, "");
llvm::BasicBlock *HandleBB = llvm::BasicBlock::Create(ctx,"HandleBlock", Fn);
llvm::BranchInst::Create(HandleBB, Inst->getParent(), Cmp, FailBB);
llvm::ReturnInst::Create(Fn->getContext(), HandleBB);
Builder->SetInsertPoint(PreInsertInst);
return FailBB;
}
void NullDerefProtectionTransformer::instrumentLoadInst(llvm::LoadInst *LI) {
llvm::Value * Addr = LI->getOperand(0);
if(llvm::isa<llvm::GlobalVariable>(Addr))
return;
llvm::PointerType* PTy = llvm::cast<llvm::PointerType>(Addr->getType());
llvm::Type * ElTy = PTy -> getElementType();
if (!ElTy->isPointerTy()) {
@ -104,6 +139,9 @@ namespace cling {
void NullDerefProtectionTransformer::instrumentStoreInst(llvm::StoreInst *SI){
llvm::Value * Addr = SI->getOperand(1);
if(llvm::isa<llvm::GlobalVariable>(Addr))
return;
llvm::PointerType* PTy = llvm::cast<llvm::PointerType>(Addr->getType());
llvm::Type * ElTy = PTy -> getElementType();
if (!ElTy->isPointerTy()) {