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//== NullDerefChecker.cpp - Null dereference checker ------------*- C++ -*--==//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This defines NullDerefChecker, a builtin check in GRExprEngine that performs
// checks for null pointers at loads and stores.
//
//===----------------------------------------------------------------------===//
#include "clang/Analysis/PathSensitive/Checkers/NullDerefChecker.h"
#include "clang/Analysis/PathSensitive/GRExprEngine.h"
#include "clang/Analysis/PathSensitive/BugReporter.h"
using namespace clang;
void *NullDerefChecker::getTag() {
static int x = 0;
return &x;
}
ExplodedNode *NullDerefChecker::CheckLocation(const Stmt *S, ExplodedNode *Pred,
const GRState *state, SVal V,
GRExprEngine &Eng) {
Loc *LV = dyn_cast<Loc>(&V);
// If the value is not a location, don't touch the node.
if (!LV)
return Pred;
const GRState *NotNullState = state->Assume(*LV, true);
const GRState *NullState = state->Assume(*LV, false);
GRStmtNodeBuilder &Builder = Eng.getBuilder();
BugReporter &BR = Eng.getBugReporter();
// The explicit NULL case.
if (NullState) {
// Use the GDM to mark in the state what lval was null.
const SVal *PersistentLV = Eng.getBasicVals().getPersistentSVal(*LV);
NullState = NullState->set<GRState::NullDerefTag>(PersistentLV);
ExplodedNode *N = Builder.generateNode(S, NullState, Pred,
ProgramPoint::PostNullCheckFailedKind);
if (N) {
N->markAsSink();
if (!NotNullState) { // Explicit null case.
if (!BT)
BT = new BuiltinBug(NULL, "Null dereference",
"Dereference of null pointer");
EnhancedBugReport *R =
new EnhancedBugReport(*BT, BT->getDescription().c_str(), N);
R->addVisitorCreator(bugreporter::registerTrackNullOrUndefValue,
bugreporter::GetDerefExpr(N));
BR.EmitReport(R);
return 0;
} else // Implicit null case.
ImplicitNullDerefNodes.push_back(N);
}
}
if (!NotNullState)
return 0;
return Builder.generateNode(S, NotNullState, Pred,
ProgramPoint::PostLocationChecksSucceedKind);
}
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