1 //=== InnerPointerChecker.cpp -------------------------------------*- C++ -*--//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file defines a check that marks a raw pointer to a C++ container's
11 // inner buffer released when the object is destroyed. This information can
12 // be used by MallocChecker to detect use-after-free problems.
14 //===----------------------------------------------------------------------===//
16 #include "AllocationState.h"
17 #include "ClangSACheckers.h"
18 #include "clang/StaticAnalyzer/Core/BugReporter/BugType.h"
19 #include "clang/StaticAnalyzer/Core/BugReporter/CommonBugCategories.h"
20 #include "clang/StaticAnalyzer/Core/Checker.h"
21 #include "clang/StaticAnalyzer/Core/PathSensitive/CallEvent.h"
22 #include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
24 using namespace clang;
27 using PtrSet = llvm::ImmutableSet<SymbolRef>;
29 // Associate container objects with a set of raw pointer symbols.
30 REGISTER_MAP_WITH_PROGRAMSTATE(RawPtrMap, const MemRegion *, PtrSet)
32 // This is a trick to gain access to PtrSet's Factory.
36 struct ProgramStateTrait<PtrSet> : public ProgramStatePartialTrait<PtrSet> {
37 static void *GDMIndex() {
42 } // end namespace ento
43 } // end namespace clang
47 class InnerPointerChecker
48 : public Checker<check::DeadSymbols, check::PostCall> {
50 CallDescription AppendFn, AssignFn, ClearFn, CStrFn, DataFn, EraseFn,
51 InsertFn, PopBackFn, PushBackFn, ReplaceFn, ReserveFn, ResizeFn,
52 ShrinkToFitFn, SwapFn;
55 class InnerPointerBRVisitor : public BugReporterVisitor {
59 InnerPointerBRVisitor(SymbolRef Sym) : PtrToBuf(Sym) {}
61 static void *getTag() {
66 void Profile(llvm::FoldingSetNodeID &ID) const override {
67 ID.AddPointer(getTag());
70 std::shared_ptr<PathDiagnosticPiece> VisitNode(const ExplodedNode *N,
71 const ExplodedNode *PrevN,
72 BugReporterContext &BRC,
73 BugReport &BR) override;
75 // FIXME: Scan the map once in the visitor's constructor and do a direct
77 bool isSymbolTracked(ProgramStateRef State, SymbolRef Sym) {
78 RawPtrMapTy Map = State->get<RawPtrMap>();
79 for (const auto Entry : Map) {
80 if (Entry.second.contains(Sym))
88 : AppendFn("append"), AssignFn("assign"), ClearFn("clear"),
89 CStrFn("c_str"), DataFn("data"), EraseFn("erase"), InsertFn("insert"),
90 PopBackFn("pop_back"), PushBackFn("push_back"), ReplaceFn("replace"),
91 ReserveFn("reserve"), ResizeFn("resize"),
92 ShrinkToFitFn("shrink_to_fit"), SwapFn("swap") {}
94 /// Check whether the function called on the container object is a
95 /// member function that potentially invalidates pointers referring
96 /// to the objects's internal buffer.
97 bool mayInvalidateBuffer(const CallEvent &Call) const;
99 /// Record the connection between the symbol returned by c_str() and the
100 /// corresponding string object region in the ProgramState. Mark the symbol
101 /// released if the string object is destroyed.
102 void checkPostCall(const CallEvent &Call, CheckerContext &C) const;
104 /// Clean up the ProgramState map.
105 void checkDeadSymbols(SymbolReaper &SymReaper, CheckerContext &C) const;
108 } // end anonymous namespace
112 // "References, pointers, and iterators referring to the elements of a
113 // basic_string sequence may be invalidated by the following uses of that
114 // basic_string object:
116 // -- TODO: As an argument to any standard library function taking a reference
117 // to non-const basic_string as an argument. For example, as an argument to
118 // non-member functions swap(), operator>>(), and getline(), or as an argument
119 // to basic_string::swap().
121 // -- Calling non-const member functions, except operator[], at, front, back,
122 // begin, rbegin, end, and rend."
124 bool InnerPointerChecker::mayInvalidateBuffer(const CallEvent &Call) const {
125 if (const auto *MemOpCall = dyn_cast<CXXMemberOperatorCall>(&Call)) {
126 OverloadedOperatorKind Opc = MemOpCall->getOriginExpr()->getOperator();
127 if (Opc == OO_Equal || Opc == OO_PlusEqual)
131 return (isa<CXXDestructorCall>(Call) || Call.isCalled(AppendFn) ||
132 Call.isCalled(AssignFn) || Call.isCalled(ClearFn) ||
133 Call.isCalled(EraseFn) || Call.isCalled(InsertFn) ||
134 Call.isCalled(PopBackFn) || Call.isCalled(PushBackFn) ||
135 Call.isCalled(ReplaceFn) || Call.isCalled(ReserveFn) ||
136 Call.isCalled(ResizeFn) || Call.isCalled(ShrinkToFitFn) ||
137 Call.isCalled(SwapFn));
140 void InnerPointerChecker::checkPostCall(const CallEvent &Call,
141 CheckerContext &C) const {
142 const auto *ICall = dyn_cast<CXXInstanceCall>(&Call);
146 SVal Obj = ICall->getCXXThisVal();
147 const auto *ObjRegion = dyn_cast_or_null<TypedValueRegion>(Obj.getAsRegion());
151 auto *TypeDecl = ObjRegion->getValueType()->getAsCXXRecordDecl();
152 if (TypeDecl->getName() != "basic_string")
155 ProgramStateRef State = C.getState();
157 if (Call.isCalled(CStrFn) || Call.isCalled(DataFn)) {
158 SVal RawPtr = Call.getReturnValue();
159 if (SymbolRef Sym = RawPtr.getAsSymbol(/*IncludeBaseRegions=*/true)) {
160 // Start tracking this raw pointer by adding it to the set of symbols
161 // associated with this container object in the program state map.
162 PtrSet::Factory &F = State->getStateManager().get_context<PtrSet>();
163 const PtrSet *SetPtr = State->get<RawPtrMap>(ObjRegion);
164 PtrSet Set = SetPtr ? *SetPtr : F.getEmptySet();
165 assert(C.wasInlined || !Set.contains(Sym));
166 Set = F.add(Set, Sym);
167 State = State->set<RawPtrMap>(ObjRegion, Set);
168 C.addTransition(State);
173 if (mayInvalidateBuffer(Call)) {
174 if (const PtrSet *PS = State->get<RawPtrMap>(ObjRegion)) {
175 // Mark all pointer symbols associated with the deleted object released.
176 const Expr *Origin = Call.getOriginExpr();
177 for (const auto Symbol : *PS) {
178 // NOTE: `Origin` may be null, and will be stored so in the symbol's
179 // `RefState` in MallocChecker's `RegionState` program state map.
180 State = allocation_state::markReleased(State, Symbol, Origin);
182 State = State->remove<RawPtrMap>(ObjRegion);
183 C.addTransition(State);
189 void InnerPointerChecker::checkDeadSymbols(SymbolReaper &SymReaper,
190 CheckerContext &C) const {
191 ProgramStateRef State = C.getState();
192 PtrSet::Factory &F = State->getStateManager().get_context<PtrSet>();
193 RawPtrMapTy RPM = State->get<RawPtrMap>();
194 for (const auto Entry : RPM) {
195 if (!SymReaper.isLiveRegion(Entry.first)) {
196 // Due to incomplete destructor support, some dead regions might
197 // remain in the program state map. Clean them up.
198 State = State->remove<RawPtrMap>(Entry.first);
200 if (const PtrSet *OldSet = State->get<RawPtrMap>(Entry.first)) {
201 PtrSet CleanedUpSet = *OldSet;
202 for (const auto Symbol : Entry.second) {
203 if (!SymReaper.isLive(Symbol))
204 CleanedUpSet = F.remove(CleanedUpSet, Symbol);
206 State = CleanedUpSet.isEmpty()
207 ? State->remove<RawPtrMap>(Entry.first)
208 : State->set<RawPtrMap>(Entry.first, CleanedUpSet);
211 C.addTransition(State);
214 std::shared_ptr<PathDiagnosticPiece>
215 InnerPointerChecker::InnerPointerBRVisitor::VisitNode(const ExplodedNode *N,
216 const ExplodedNode *PrevN,
217 BugReporterContext &BRC,
220 if (!isSymbolTracked(N->getState(), PtrToBuf) ||
221 isSymbolTracked(PrevN->getState(), PtrToBuf))
224 const Stmt *S = PathDiagnosticLocation::getStmt(N);
228 SmallString<256> Buf;
229 llvm::raw_svector_ostream OS(Buf);
230 OS << "Dangling inner pointer obtained here";
231 PathDiagnosticLocation Pos(S, BRC.getSourceManager(),
232 N->getLocationContext());
233 return std::make_shared<PathDiagnosticEventPiece>(Pos, OS.str(), true,
239 namespace allocation_state {
241 std::unique_ptr<BugReporterVisitor> getInnerPointerBRVisitor(SymbolRef Sym) {
242 return llvm::make_unique<InnerPointerChecker::InnerPointerBRVisitor>(Sym);
245 } // end namespace allocation_state
246 } // end namespace ento
247 } // end namespace clang
249 void ento::registerInnerPointerChecker(CheckerManager &Mgr) {
250 registerNewDeleteChecker(Mgr);
251 Mgr.registerChecker<InnerPointerChecker>();