void DereferenceChecker::reportBug(ProgramStateRef State, const Stmt *S,
CheckerContext &C, bool IsBind) const {
// Generate an error node.
ExplodedNode *N = C.generateSink(State);
if (!N)
return;
// We know that 'location' cannot be non-null. This is what
// we call an "explicit" null dereference.
if (!BT_null)
BT_null.reset(new BuiltinBug("Dereference of null pointer"));
SmallString<100> buf;
SmallVector<SourceRange, 2> Ranges;
// Walk through lvalue casts to get the original expression
// that syntactically caused the load.
if (const Expr *expr = dyn_cast<Expr>(S))
S = expr->IgnoreParenLValueCasts();
const MemRegion *sourceR = 0;
if (IsBind) {
if (const BinaryOperator *BO = dyn_cast<BinaryOperator>(S)) {
if (BO->isAssignmentOp())
S = BO->getRHS();
} else if (const DeclStmt *DS = dyn_cast<DeclStmt>(S)) {
assert(DS->isSingleDecl() && "We process decls one by one");
if (const VarDecl *VD = dyn_cast<VarDecl>(DS->getSingleDecl()))
if (const Expr *Init = VD->getAnyInitializer())
S = Init;
}
}
switch (S->getStmtClass()) {
case Stmt::ArraySubscriptExprClass: {
llvm::raw_svector_ostream os(buf);
os << "Array access";
const ArraySubscriptExpr *AE = cast<ArraySubscriptExpr>(S);
sourceR = AddDerefSource(os, Ranges, AE->getBase()->IgnoreParenCasts(),
State.getPtr(), N->getLocationContext());
os << " results in a null pointer dereference";
break;
}
case Stmt::UnaryOperatorClass: {
llvm::raw_svector_ostream os(buf);
os << "Dereference of null pointer";
const UnaryOperator *U = cast<UnaryOperator>(S);
sourceR = AddDerefSource(os, Ranges, U->getSubExpr()->IgnoreParens(),
State.getPtr(), N->getLocationContext(), true);
break;
}
case Stmt::MemberExprClass: {
const MemberExpr *M = cast<MemberExpr>(S);
if (M->isArrow()) {
llvm::raw_svector_ostream os(buf);
os << "Access to field '" << M->getMemberNameInfo()
<< "' results in a dereference of a null pointer";
sourceR = AddDerefSource(os, Ranges, M->getBase()->IgnoreParenCasts(),
State.getPtr(), N->getLocationContext(), true);
}
break;
}
case Stmt::ObjCIvarRefExprClass: {
const ObjCIvarRefExpr *IV = cast<ObjCIvarRefExpr>(S);
if (const DeclRefExpr *DR =
dyn_cast<DeclRefExpr>(IV->getBase()->IgnoreParenCasts())) {
if (const VarDecl *VD = dyn_cast<VarDecl>(DR->getDecl())) {
llvm::raw_svector_ostream os(buf);
os << "Instance variable access (via '" << VD->getName()
<< "') results in a null pointer dereference";
}
}
Ranges.push_back(IV->getSourceRange());
break;
}
default:
break;
}
BugReport *report =
new BugReport(*BT_null,
buf.empty() ? BT_null->getDescription() : buf.str(),
N);
bugreporter::addTrackNullOrUndefValueVisitor(N, bugreporter::GetDerefExpr(N),
report);
for (SmallVectorImpl<SourceRange>::iterator
I = Ranges.begin(), E = Ranges.end(); I!=E; ++I)
report->addRange(*I);
if (sourceR) {
report->markInteresting(sourceR);
report->markInteresting(State->getRawSVal(loc::MemRegionVal(sourceR)));
}
C.EmitReport(report);
}
