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//=== InnerPointerChecker.cpp -------------------------------------*- C++ -*--//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
// This file defines a check that marks a raw pointer to a C++ container's
// inner buffer released when the object is destroyed. This information can
// be used by MallocChecker to detect use-after-free problems.
#include "AllocationState.h"
#include "clang/StaticAnalyzer/Checkers/BuiltinCheckerRegistration.h"
#include "InterCheckerAPI.h"
#include "clang/StaticAnalyzer/Core/BugReporter/BugType.h"
#include "clang/StaticAnalyzer/Core/BugReporter/CommonBugCategories.h"
#include "clang/StaticAnalyzer/Core/Checker.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/CallEvent.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
using namespace clang;
using namespace ento;
// Associate container objects with a set of raw pointer symbols.
REGISTER_MAP_WITH_PROGRAMSTATE(RawPtrMap, const MemRegion *, PtrSet)
namespace {
class InnerPointerChecker
: public Checker<check::DeadSymbols, check::PostCall> {
CallDescription AppendFn, AssignFn, ClearFn, CStrFn, DataFn, EraseFn,
InsertFn, PopBackFn, PushBackFn, ReplaceFn, ReserveFn, ResizeFn,
ShrinkToFitFn, SwapFn;
class InnerPointerBRVisitor : public BugReporterVisitor {
SymbolRef PtrToBuf;
InnerPointerBRVisitor(SymbolRef Sym) : PtrToBuf(Sym) {}
static void *getTag() {
static int Tag = 0;
return &Tag;
void Profile(llvm::FoldingSetNodeID &ID) const override {
virtual PathDiagnosticPieceRef
VisitNode(const ExplodedNode *N, BugReporterContext &BRC,
PathSensitiveBugReport &BR) override;
// FIXME: Scan the map once in the visitor's constructor and do a direct
// lookup by region.
bool isSymbolTracked(ProgramStateRef State, SymbolRef Sym) {
RawPtrMapTy Map = State->get<RawPtrMap>();
for (const auto Entry : Map) {
if (Entry.second.contains(Sym))
return true;
return false;
: AppendFn({"std", "basic_string", "append"}),
AssignFn({"std", "basic_string", "assign"}),
ClearFn({"std", "basic_string", "clear"}),
CStrFn({"std", "basic_string", "c_str"}),
DataFn({"std", "basic_string", "data"}),
EraseFn({"std", "basic_string", "erase"}),
InsertFn({"std", "basic_string", "insert"}),
PopBackFn({"std", "basic_string", "pop_back"}),
PushBackFn({"std", "basic_string", "push_back"}),
ReplaceFn({"std", "basic_string", "replace"}),
ReserveFn({"std", "basic_string", "reserve"}),
ResizeFn({"std", "basic_string", "resize"}),
ShrinkToFitFn({"std", "basic_string", "shrink_to_fit"}),
SwapFn({"std", "basic_string", "swap"}) {}
/// Check whether the called member function potentially invalidates
/// pointers referring to the container object's inner buffer.
bool isInvalidatingMemberFunction(const CallEvent &Call) const;
/// Mark pointer symbols associated with the given memory region released
/// in the program state.
void markPtrSymbolsReleased(const CallEvent &Call, ProgramStateRef State,
const MemRegion *ObjRegion,
CheckerContext &C) const;
/// Standard library functions that take a non-const `basic_string` argument by
/// reference may invalidate its inner pointers. Check for these cases and
/// mark the pointers released.
void checkFunctionArguments(const CallEvent &Call, ProgramStateRef State,
CheckerContext &C) const;
/// Record the connection between raw pointers referring to a container
/// object's inner buffer and the object's memory region in the program state.
/// Mark potentially invalidated pointers released.
void checkPostCall(const CallEvent &Call, CheckerContext &C) const;
/// Clean up the program state map.
void checkDeadSymbols(SymbolReaper &SymReaper, CheckerContext &C) const;
} // end anonymous namespace
bool InnerPointerChecker::isInvalidatingMemberFunction(
const CallEvent &Call) const {
if (const auto *MemOpCall = dyn_cast<CXXMemberOperatorCall>(&Call)) {
OverloadedOperatorKind Opc = MemOpCall->getOriginExpr()->getOperator();
if (Opc == OO_Equal || Opc == OO_PlusEqual)
return true;
return false;
return (isa<CXXDestructorCall>(Call) || Call.isCalled(AppendFn) ||
Call.isCalled(AssignFn) || Call.isCalled(ClearFn) ||
Call.isCalled(EraseFn) || Call.isCalled(InsertFn) ||
Call.isCalled(PopBackFn) || Call.isCalled(PushBackFn) ||
Call.isCalled(ReplaceFn) || Call.isCalled(ReserveFn) ||
Call.isCalled(ResizeFn) || Call.isCalled(ShrinkToFitFn) ||
void InnerPointerChecker::markPtrSymbolsReleased(const CallEvent &Call,
ProgramStateRef State,
const MemRegion *MR,
CheckerContext &C) const {
if (const PtrSet *PS = State->get<RawPtrMap>(MR)) {
const Expr *Origin = Call.getOriginExpr();
for (const auto Symbol : *PS) {
// NOTE: `Origin` may be null, and will be stored so in the symbol's
// `RefState` in MallocChecker's `RegionState` program state map.
State = allocation_state::markReleased(State, Symbol, Origin);
State = State->remove<RawPtrMap>(MR);
void InnerPointerChecker::checkFunctionArguments(const CallEvent &Call,
ProgramStateRef State,
CheckerContext &C) const {
if (const auto *FC = dyn_cast<AnyFunctionCall>(&Call)) {
const FunctionDecl *FD = FC->getDecl();
if (!FD || !FD->isInStdNamespace())
for (unsigned I = 0, E = FD->getNumParams(); I != E; ++I) {
QualType ParamTy = FD->getParamDecl(I)->getType();
if (!ParamTy->isReferenceType() ||
// In case of member operator calls, `this` is counted as an
// argument but not as a parameter.
bool isaMemberOpCall = isa<CXXMemberOperatorCall>(FC);
unsigned ArgI = isaMemberOpCall ? I+1 : I;
SVal Arg = FC->getArgSVal(ArgI);
const auto *ArgRegion =
if (!ArgRegion)
markPtrSymbolsReleased(Call, State, ArgRegion, C);
// [string.require]
// "References, pointers, and iterators referring to the elements of a
// basic_string sequence may be invalidated by the following uses of that
// basic_string object:
// -- As an argument to any standard library function taking a reference
// to non-const basic_string as an argument. For example, as an argument to
// non-member functions swap(), operator>>(), and getline(), or as an argument
// to basic_string::swap().
// -- Calling non-const member functions, except operator[], at, front, back,
// begin, rbegin, end, and rend."
void InnerPointerChecker::checkPostCall(const CallEvent &Call,
CheckerContext &C) const {
ProgramStateRef State = C.getState();
if (const auto *ICall = dyn_cast<CXXInstanceCall>(&Call)) {
// TODO: Do we need these to be typed?
const auto *ObjRegion = dyn_cast_or_null<TypedValueRegion>(
if (!ObjRegion)
if (Call.isCalled(CStrFn) || Call.isCalled(DataFn)) {
SVal RawPtr = Call.getReturnValue();
if (SymbolRef Sym = RawPtr.getAsSymbol(/*IncludeBaseRegions=*/true)) {
// Start tracking this raw pointer by adding it to the set of symbols
// associated with this container object in the program state map.
PtrSet::Factory &F = State->getStateManager().get_context<PtrSet>();
const PtrSet *SetPtr = State->get<RawPtrMap>(ObjRegion);
PtrSet Set = SetPtr ? *SetPtr : F.getEmptySet();
assert(C.wasInlined || !Set.contains(Sym));
Set = F.add(Set, Sym);
State = State->set<RawPtrMap>(ObjRegion, Set);
// Check [string.require] / second point.
if (isInvalidatingMemberFunction(Call)) {
markPtrSymbolsReleased(Call, State, ObjRegion, C);
// Check [string.require] / first point.
checkFunctionArguments(Call, State, C);
void InnerPointerChecker::checkDeadSymbols(SymbolReaper &SymReaper,
CheckerContext &C) const {
ProgramStateRef State = C.getState();
PtrSet::Factory &F = State->getStateManager().get_context<PtrSet>();
RawPtrMapTy RPM = State->get<RawPtrMap>();
for (const auto Entry : RPM) {
if (!SymReaper.isLiveRegion(Entry.first)) {
// Due to incomplete destructor support, some dead regions might
// remain in the program state map. Clean them up.
State = State->remove<RawPtrMap>(Entry.first);
if (const PtrSet *OldSet = State->get<RawPtrMap>(Entry.first)) {
PtrSet CleanedUpSet = *OldSet;
for (const auto Symbol : Entry.second) {
if (!SymReaper.isLive(Symbol))
CleanedUpSet = F.remove(CleanedUpSet, Symbol);
State = CleanedUpSet.isEmpty()
? State->remove<RawPtrMap>(Entry.first)
: State->set<RawPtrMap>(Entry.first, CleanedUpSet);
namespace clang {
namespace ento {
namespace allocation_state {
std::unique_ptr<BugReporterVisitor> getInnerPointerBRVisitor(SymbolRef Sym) {
return std::make_unique<InnerPointerChecker::InnerPointerBRVisitor>(Sym);
const MemRegion *getContainerObjRegion(ProgramStateRef State, SymbolRef Sym) {
RawPtrMapTy Map = State->get<RawPtrMap>();
for (const auto Entry : Map) {
if (Entry.second.contains(Sym)) {
return Entry.first;
return nullptr;
} // end namespace allocation_state
} // end namespace ento
} // end namespace clang
PathDiagnosticPieceRef InnerPointerChecker::InnerPointerBRVisitor::VisitNode(
const ExplodedNode *N, BugReporterContext &BRC, PathSensitiveBugReport &) {
if (!isSymbolTracked(N->getState(), PtrToBuf) ||
isSymbolTracked(N->getFirstPred()->getState(), PtrToBuf))
return nullptr;
const Stmt *S = N->getStmtForDiagnostics();
if (!S)
return nullptr;
const MemRegion *ObjRegion =
allocation_state::getContainerObjRegion(N->getState(), PtrToBuf);
const auto *TypedRegion = cast<TypedValueRegion>(ObjRegion);
QualType ObjTy = TypedRegion->getValueType();
SmallString<256> Buf;
llvm::raw_svector_ostream OS(Buf);
OS << "Pointer to inner buffer of '" << ObjTy.getAsString()
<< "' obtained here";
PathDiagnosticLocation Pos(S, BRC.getSourceManager(),
return std::make_shared<PathDiagnosticEventPiece>(Pos, OS.str(), true);
void ento::registerInnerPointerChecker(CheckerManager &Mgr) {
bool ento::shouldRegisterInnerPointerChecker(const LangOptions &LO) {
return true;