void ArrayBoundChecker::checkLocation(SVal l, bool isLoad, const Stmt* LoadS,
CheckerContext &C) const {
// Check for out of bound array element access.
const MemRegion *R = l.getAsRegion();
if (!R)
return;
const ElementRegion *ER = dyn_cast<ElementRegion>(R);
if (!ER)
return;
// Get the index of the accessed element.
DefinedOrUnknownSVal Idx = ER->getIndex().castAs<DefinedOrUnknownSVal>();
// Zero index is always in bound, this also passes ElementRegions created for
// pointer casts.
if (Idx.isZeroConstant())
return;
ProgramStateRef state = C.getState();
// Get the size of the array.
DefinedOrUnknownSVal NumElements
= C.getStoreManager().getSizeInElements(state, ER->getSuperRegion(),
ER->getValueType());
ProgramStateRef StInBound = state->assumeInBound(Idx, NumElements, true);
ProgramStateRef StOutBound = state->assumeInBound(Idx, NumElements, false);
if (StOutBound && !StInBound) {
ExplodedNode *N = C.generateErrorNode(StOutBound);
if (!N)
return;
if (!BT)
BT.reset(new BuiltinBug(
this, "Out-of-bound array access",
"Access out-of-bound array element (buffer overflow)"));
// FIXME: It would be nice to eventually make this diagnostic more clear,
// e.g., by referencing the original declaration or by saying *why* this
// reference is outside the range.
// Generate a report for this bug.
auto report = llvm::make_unique<BugReport>(*BT, BT->getDescription(), N);
report->addRange(LoadS->getSourceRange());
C.emitReport(std::move(report));
return;
}
// Array bound check succeeded. From this point forward the array bound
// should always succeed.
C.addTransition(StInBound);
}
void ReturnPointerRangeChecker::checkPreStmt(const ReturnStmt *RS,
CheckerContext &C) const {
ProgramStateRef state = C.getState();
const Expr *RetE = RS->getRetValue();
if (!RetE)
return;
SVal V = state->getSVal(RetE, C.getLocationContext());
const MemRegion *R = V.getAsRegion();
const ElementRegion *ER = dyn_cast_or_null<ElementRegion>(R);
if (!ER)
return;
DefinedOrUnknownSVal Idx = ER->getIndex().castAs<DefinedOrUnknownSVal>();
// Zero index is always in bound, this also passes ElementRegions created for
// pointer casts.
if (Idx.isZeroConstant())
return;
// FIXME: All of this out-of-bounds checking should eventually be refactored
// into a common place.
DefinedOrUnknownSVal NumElements
= C.getStoreManager().getSizeInElements(state, ER->getSuperRegion(),
ER->getValueType());
ProgramStateRef StInBound = state->assumeInBound(Idx, NumElements, true);
ProgramStateRef StOutBound = state->assumeInBound(Idx, NumElements, false);
if (StOutBound && !StInBound) {
ExplodedNode *N = C.generateSink(StOutBound);
if (!N)
return;
// FIXME: This bug correspond to CWE-466. Eventually we should have bug
// types explicitly reference such exploit categories (when applicable).
if (!BT)
BT.reset(new BuiltinBug(
this, "Return of pointer value outside of expected range",
"Returned pointer value points outside the original object "
"(potential buffer overflow)"));
// FIXME: It would be nice to eventually make this diagnostic more clear,
// e.g., by referencing the original declaration or by saying *why* this
// reference is outside the range.
// Generate a report for this bug.
auto report = llvm::make_unique<BugReport>(*BT, BT->getDescription(), N);
report->addRange(RetE->getSourceRange());
C.emitReport(std::move(report));
}
}
void ObjCContainersChecker::checkPreStmt(const CallExpr *CE,
CheckerContext &C) const {
StringRef Name = C.getCalleeName(CE);
if (Name.empty() || CE->getNumArgs() < 2)
return;
// Check the array access.
if (Name.equals("CFArrayGetValueAtIndex")) {
ProgramStateRef State = C.getState();
// Retrieve the size.
// Find out if we saw this array symbol before and have information about
// it.
const Expr *ArrayExpr = CE->getArg(0);
SymbolRef ArraySym = getArraySym(ArrayExpr, C);
if (!ArraySym)
return;
const DefinedSVal *Size = State->get<ArraySizeMap>(ArraySym);
if (!Size)
return;
// Get the index.
const Expr *IdxExpr = CE->getArg(1);
SVal IdxVal = State->getSVal(IdxExpr, C.getLocationContext());
if (IdxVal.isUnknownOrUndef())
return;
DefinedSVal Idx = IdxVal.castAs<DefinedSVal>();
// Now, check if 'Idx in [0, Size-1]'.
const QualType T = IdxExpr->getType();
ProgramStateRef StInBound = State->assumeInBound(Idx, *Size, true, T);
ProgramStateRef StOutBound = State->assumeInBound(Idx, *Size, false, T);
if (StOutBound && !StInBound) {
ExplodedNode *N = C.generateSink(StOutBound);
if (!N)
return;
initBugType();
auto R = llvm::make_unique<BugReport>(*BT, "Index is out of bounds", N);
R->addRange(IdxExpr->getSourceRange());
C.emitReport(std::move(R));
return;
}
}
}
