clang 10.0.0git

InnerPointerChecker.cpp
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1 //=== InnerPointerChecker.cpp -------------------------------------*- C++ -*--//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // This file defines a check that marks a raw pointer to a C++ container's
10 // inner buffer released when the object is destroyed. This information can
11 // be used by MallocChecker to detect use-after-free problems.
12 //
13 //===----------------------------------------------------------------------===//
14
15 #include "AllocationState.h"
16 #include "clang/StaticAnalyzer/Checkers/BuiltinCheckerRegistration.h"
17 #include "InterCheckerAPI.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"
23
24 using namespace clang;
25 using namespace ento;
26
27 // Associate container objects with a set of raw pointer symbols.
28 REGISTER_SET_FACTORY_WITH_PROGRAMSTATE(PtrSet, SymbolRef)
29 REGISTER_MAP_WITH_PROGRAMSTATE(RawPtrMap, const MemRegion *, PtrSet)
30
31
32 namespace {
33
34 class InnerPointerChecker
35 : public Checker<check::DeadSymbols, check::PostCall> {
36
37 CallDescription AppendFn, AssignFn, ClearFn, CStrFn, DataFn, EraseFn,
38 InsertFn, PopBackFn, PushBackFn, ReplaceFn, ReserveFn, ResizeFn,
39 ShrinkToFitFn, SwapFn;
40
41 public:
42 class InnerPointerBRVisitor : public BugReporterVisitor {
43 SymbolRef PtrToBuf;
44
45 public:
46 InnerPointerBRVisitor(SymbolRef Sym) : PtrToBuf(Sym) {}
47
48 static void *getTag() {
49 static int Tag = 0;
50 return &Tag;
51 }
52
53 void Profile(llvm::FoldingSetNodeID &ID) const override {
54 ID.AddPointer(getTag());
55 }
56
57 virtual PathDiagnosticPieceRef
58 VisitNode(const ExplodedNode *N, BugReporterContext &BRC,
59 PathSensitiveBugReport &BR) override;
60
61 // FIXME: Scan the map once in the visitor's constructor and do a direct
62 // lookup by region.
63 bool isSymbolTracked(ProgramStateRef State, SymbolRef Sym) {
64 RawPtrMapTy Map = State->get<RawPtrMap>();
65 for (const auto &Entry : Map) {
66 if (Entry.second.contains(Sym))
67 return true;
68 }
69 return false;
70 }
71 };
72
73 InnerPointerChecker()
74 : AppendFn({"std", "basic_string", "append"}),
75 AssignFn({"std", "basic_string", "assign"}),
76 ClearFn({"std", "basic_string", "clear"}),
77 CStrFn({"std", "basic_string", "c_str"}),
78 DataFn({"std", "basic_string", "data"}),
79 EraseFn({"std", "basic_string", "erase"}),
80 InsertFn({"std", "basic_string", "insert"}),
81 PopBackFn({"std", "basic_string", "pop_back"}),
82 PushBackFn({"std", "basic_string", "push_back"}),
83 ReplaceFn({"std", "basic_string", "replace"}),
84 ReserveFn({"std", "basic_string", "reserve"}),
85 ResizeFn({"std", "basic_string", "resize"}),
86 ShrinkToFitFn({"std", "basic_string", "shrink_to_fit"}),
87 SwapFn({"std", "basic_string", "swap"}) {}
88
89 /// Check whether the called member function potentially invalidates
90 /// pointers referring to the container object's inner buffer.
91 bool isInvalidatingMemberFunction(const CallEvent &Call) const;
92
93 /// Mark pointer symbols associated with the given memory region released
94 /// in the program state.
95 void markPtrSymbolsReleased(const CallEvent &Call, ProgramStateRef State,
96 const MemRegion *ObjRegion,
97 CheckerContext &C) const;
98
99 /// Standard library functions that take a non-const `basic_string` argument by
100 /// reference may invalidate its inner pointers. Check for these cases and
101 /// mark the pointers released.
102 void checkFunctionArguments(const CallEvent &Call, ProgramStateRef State,
103 CheckerContext &C) const;
104
105 /// Record the connection between raw pointers referring to a container
106 /// object's inner buffer and the object's memory region in the program state.
107 /// Mark potentially invalidated pointers released.
108 void checkPostCall(const CallEvent &Call, CheckerContext &C) const;
109
110 /// Clean up the program state map.
111 void checkDeadSymbols(SymbolReaper &SymReaper, CheckerContext &C) const;
112 };
113
114 } // end anonymous namespace
115
116 bool InnerPointerChecker::isInvalidatingMemberFunction(
117 const CallEvent &Call) const {
118 if (const auto *MemOpCall = dyn_cast<CXXMemberOperatorCall>(&Call)) {
119 OverloadedOperatorKind Opc = MemOpCall->getOriginExpr()->getOperator();
120 if (Opc == OO_Equal || Opc == OO_PlusEqual)
121 return true;
122 return false;
123 }
124 return (isa<CXXDestructorCall>(Call) || Call.isCalled(AppendFn) ||
125 Call.isCalled(AssignFn) || Call.isCalled(ClearFn) ||
126 Call.isCalled(EraseFn) || Call.isCalled(InsertFn) ||
127 Call.isCalled(PopBackFn) || Call.isCalled(PushBackFn) ||
128 Call.isCalled(ReplaceFn) || Call.isCalled(ReserveFn) ||
129 Call.isCalled(ResizeFn) || Call.isCalled(ShrinkToFitFn) ||
130 Call.isCalled(SwapFn));
131 }
132
133 void InnerPointerChecker::markPtrSymbolsReleased(const CallEvent &Call,
134 ProgramStateRef State,
135 const MemRegion *MR,
136 CheckerContext &C) const {
137 if (const PtrSet *PS = State->get<RawPtrMap>(MR)) {
138 const Expr *Origin = Call.getOriginExpr();
139 for (const auto Symbol : *PS) {
140 // NOTE: `Origin` may be null, and will be stored so in the symbol's
141 // `RefState` in MallocChecker's `RegionState` program state map.
142 State = allocation_state::markReleased(State, Symbol, Origin);
143 }
144 State = State->remove<RawPtrMap>(MR);
145 C.addTransition(State);
146 return;
147 }
148 }
149
150 void InnerPointerChecker::checkFunctionArguments(const CallEvent &Call,
151 ProgramStateRef State,
152 CheckerContext &C) const {
153 if (const auto *FC = dyn_cast<AnyFunctionCall>(&Call)) {
154 const FunctionDecl *FD = FC->getDecl();
155 if (!FD || !FD->isInStdNamespace())
156 return;
157
158 for (unsigned I = 0, E = FD->getNumParams(); I != E; ++I) {
159 QualType ParamTy = FD->getParamDecl(I)->getType();
160 if (!ParamTy->isReferenceType() ||
161 ParamTy->getPointeeType().isConstQualified())
162 continue;
163
164 // In case of member operator calls, `this` is counted as an
165 // argument but not as a parameter.
166 bool isaMemberOpCall = isa<CXXMemberOperatorCall>(FC);
167 unsigned ArgI = isaMemberOpCall ? I+1 : I;
168
169 SVal Arg = FC->getArgSVal(ArgI);
170 const auto *ArgRegion =
171 dyn_cast_or_null<TypedValueRegion>(Arg.getAsRegion());
172 if (!ArgRegion)
173 continue;
174
175 markPtrSymbolsReleased(Call, State, ArgRegion, C);
176 }
177 }
178 }
179
180 // [string.require]
181 //
182 // "References, pointers, and iterators referring to the elements of a
183 // basic_string sequence may be invalidated by the following uses of that
184 // basic_string object:
185 //
186 // -- As an argument to any standard library function taking a reference
187 // to non-const basic_string as an argument. For example, as an argument to
188 // non-member functions swap(), operator>>(), and getline(), or as an argument
189 // to basic_string::swap().
190 //
191 // -- Calling non-const member functions, except operator[], at, front, back,
192 // begin, rbegin, end, and rend."
193
194 void InnerPointerChecker::checkPostCall(const CallEvent &Call,
195 CheckerContext &C) const {
196 ProgramStateRef State = C.getState();
197
198 if (const auto *ICall = dyn_cast<CXXInstanceCall>(&Call)) {
199 // TODO: Do we need these to be typed?
200 const auto *ObjRegion = dyn_cast_or_null<TypedValueRegion>(
201 ICall->getCXXThisVal().getAsRegion());
202 if (!ObjRegion)
203 return;
204
205 if (Call.isCalled(CStrFn) || Call.isCalled(DataFn)) {
206 SVal RawPtr = Call.getReturnValue();
207 if (SymbolRef Sym = RawPtr.getAsSymbol(/*IncludeBaseRegions=*/true)) {
208 // Start tracking this raw pointer by adding it to the set of symbols
209 // associated with this container object in the program state map.
210
211 PtrSet::Factory &F = State->getStateManager().get_context<PtrSet>();
212 const PtrSet *SetPtr = State->get<RawPtrMap>(ObjRegion);
213 PtrSet Set = SetPtr ? *SetPtr : F.getEmptySet();
214 assert(C.wasInlined || !Set.contains(Sym));
215 Set = F.add(Set, Sym);
216
217 State = State->set<RawPtrMap>(ObjRegion, Set);
218 C.addTransition(State);
219 }
220 return;
221 }
222
223 // Check [string.require] / second point.
224 if (isInvalidatingMemberFunction(Call)) {
225 markPtrSymbolsReleased(Call, State, ObjRegion, C);
226 return;
227 }
228 }
229
230 // Check [string.require] / first point.
231 checkFunctionArguments(Call, State, C);
232 }
233
234 void InnerPointerChecker::checkDeadSymbols(SymbolReaper &SymReaper,
235 CheckerContext &C) const {
236 ProgramStateRef State = C.getState();
237 PtrSet::Factory &F = State->getStateManager().get_context<PtrSet>();
238 RawPtrMapTy RPM = State->get<RawPtrMap>();
239 for (const auto &Entry : RPM) {
240 if (!SymReaper.isLiveRegion(Entry.first)) {
241 // Due to incomplete destructor support, some dead regions might
242 // remain in the program state map. Clean them up.
243 State = State->remove<RawPtrMap>(Entry.first);
244 }
245 if (const PtrSet *OldSet = State->get<RawPtrMap>(Entry.first)) {
246 PtrSet CleanedUpSet = *OldSet;
247 for (const auto Symbol : Entry.second) {
248 if (!SymReaper.isLive(Symbol))
249 CleanedUpSet = F.remove(CleanedUpSet, Symbol);
250 }
251 State = CleanedUpSet.isEmpty()
252 ? State->remove<RawPtrMap>(Entry.first)
253 : State->set<RawPtrMap>(Entry.first, CleanedUpSet);
254 }
255 }
256 C.addTransition(State);
257 }
258
259 namespace clang {
260 namespace ento {
261 namespace allocation_state {
262
263 std::unique_ptr<BugReporterVisitor> getInnerPointerBRVisitor(SymbolRef Sym) {
264 return std::make_unique<InnerPointerChecker::InnerPointerBRVisitor>(Sym);
265 }
266
267 const MemRegion *getContainerObjRegion(ProgramStateRef State, SymbolRef Sym) {
268 RawPtrMapTy Map = State->get<RawPtrMap>();
269 for (const auto &Entry : Map) {
270 if (Entry.second.contains(Sym)) {
271 return Entry.first;
272 }
273 }
274 return nullptr;
275 }
276
277 } // end namespace allocation_state
278 } // end namespace ento
279 } // end namespace clang
280
281 PathDiagnosticPieceRef InnerPointerChecker::InnerPointerBRVisitor::VisitNode(
282 const ExplodedNode *N, BugReporterContext &BRC, PathSensitiveBugReport &) {
283 if (!isSymbolTracked(N->getState(), PtrToBuf) ||
284 isSymbolTracked(N->getFirstPred()->getState(), PtrToBuf))
285 return nullptr;
286
287 const Stmt *S = N->getStmtForDiagnostics();
288 if (!S)
289 return nullptr;
290
291 const MemRegion *ObjRegion =
292 allocation_state::getContainerObjRegion(N->getState(), PtrToBuf);
293 const auto *TypedRegion = cast<TypedValueRegion>(ObjRegion);
294 QualType ObjTy = TypedRegion->getValueType();
295
296 SmallString<256> Buf;
297 llvm::raw_svector_ostream OS(Buf);
298 OS << "Pointer to inner buffer of '" << ObjTy.getAsString()
299 << "' obtained here";
300 PathDiagnosticLocation Pos(S, BRC.getSourceManager(),
301 N->getLocationContext());
302 return std::make_shared<PathDiagnosticEventPiece>(Pos, OS.str(), true);
303 }
304
305 void ento::registerInnerPointerChecker(CheckerManager &Mgr) {
306 registerInnerPointerCheckerAux(Mgr);
307 Mgr.registerChecker<InnerPointerChecker>();
308 }
309
310 bool ento::shouldRegisterInnerPointerChecker(const LangOptions &LO) {
311 return true;
312 }
clang::Builtin::ID
ID
Definition: Builtins.h:46
ento
clang::FunctionDecl
Represents a function declaration or definition.
Definition: Decl.h:1783
clang::QualType
A (possibly-)qualified type.
Definition: Type.h:654
clang::ento::MemRegion
MemRegion - The root abstract class for all memory regions.
Definition: MemRegion.h:94
clang::ento::ExplodedNode::getStmtForDiagnostics
const Stmt * getStmtForDiagnostics() const
If the node&#39;s program point corresponds to a statement, retrieve that statement.
Definition: ExplodedGraph.cpp:322
clang::Stmt
Stmt - This represents one statement.
Definition: Stmt.h:66
clang::Type::getPointeeType
QualType getPointeeType() const
If this is a pointer, ObjC object pointer, or block pointer, this returns the respective pointee...
Definition: Type.cpp:557
clang::ento::registerInnerPointerCheckerAux
void registerInnerPointerCheckerAux(CheckerManager &Mgr)
Register the part of MallocChecker connected to InnerPointerChecker.
Definition: MallocChecker.cpp:3398
clang::ento::ProgramStateRef
IntrusiveRefCntPtr< const ProgramState > ProgramStateRef
Definition: ProgramState_Fwd.h:37
clang::ento::allocation_state::getContainerObjRegion
const MemRegion * getContainerObjRegion(ProgramStateRef State, SymbolRef Sym)
&#39;Sym&#39; represents a pointer to the inner buffer of a container object.
Definition: InnerPointerChecker.cpp:267
BugType.h
clang::ento::ExplodedNode::getState
const ProgramStateRef & getState() const
Definition: ExplodedGraph.h:169
clang::ento::CheckerManager
Definition: CheckerManager.h:123
AllocationState.h
BugReporterVisitor
clang::ento::SymExpr
Symbolic value.
Definition: SymExpr.h:29
clang::ento::SymbolRef
const SymExpr * SymbolRef
Definition: SymExpr.h:110
clang::ento::PathSensitiveBugReport
Definition: BugReporter.h:289
State
LineState State
Definition: UnwrappedLineFormatter.cpp:932
clang::ento::PathDiagnosticLocation
Definition: PathDiagnostic.h:157
Checker.h
clang::Type::isReferenceType
bool isReferenceType() const
Definition: Type.h:6516
clang::ento::allocation_state::getInnerPointerBRVisitor
std::unique_ptr< BugReporterVisitor > getInnerPointerBRVisitor(SymbolRef Sym)
This function provides an additional visitor that augments the bug report with information relevant t...
Definition: InnerPointerChecker.cpp:263
clang::ento::ExplodedNode
Definition: ExplodedGraph.h:65
clang::LangOptions
Keeps track of the various options that can be enabled, which controls the dialect of C or C++ that i...
Definition: LangOptions.h:53
clang::ento::PathDiagnosticPieceRef
std::shared_ptr< PathDiagnosticPiece > PathDiagnosticPieceRef
Definition: PathDiagnostic.h:454
clang::CallDescription
This class represents a description of a function call using the number of arguments and the name of ...
Definition: CallEvent.h:1058
clang::ento::ExplodedNode::getLocationContext
const LocationContext * getLocationContext() const
Definition: ExplodedGraph.h:146
clang::ento::ExplodedNode::getFirstPred
ExplodedNode * getFirstPred()
Definition: ExplodedGraph.h:210
llvm::SmallString
Definition: LLVM.h:34
clang::Expr
This represents one expression.
Definition: Expr.h:108
clang::ento::BugReporterContext
Definition: BugReporter.h:690
CommonBugCategories.h
BuiltinCheckerRegistration.h
clang::QualType::isConstQualified
bool isConstQualified() const
Determine whether this type is const-qualified.
Definition: Type.h:6315
clang::ento::BugReporterContext::getSourceManager
const SourceManager & getSourceManager() const
Definition: BugReporter.h:710
llvm::IntrusiveRefCntPtr< const ProgramState >
clang::ento::CheckerManager::registerChecker
CHECKER * registerChecker(AT &&... Args)
Used to register checkers.
Definition: CheckerManager.h:166
REGISTER_MAP_WITH_PROGRAMSTATE
#define REGISTER_MAP_WITH_PROGRAMSTATE(Name, Key, Value)
Declares an immutable map of type NameTy, suitable for placement into the ProgramState.
Definition: ProgramStateTrait.h:84
REGISTER_SET_FACTORY_WITH_PROGRAMSTATE
#define REGISTER_SET_FACTORY_WITH_PROGRAMSTATE(Name, Elem)
Declares an immutable set type Name and registers the factory for such sets in the program state...
Definition: ProgramStateTrait.h:116
clang::FunctionDecl::getParamDecl
const ParmVarDecl * getParamDecl(unsigned i) const
Definition: Decl.h:2422
clang
Dataflow Directional Tag Classes.
Definition: CFGReachabilityAnalysis.h:21
InterCheckerAPI.h
clang::OverloadedOperatorKind
OverloadedOperatorKind
Enumeration specifying the different kinds of C++ overloaded operators.
Definition: OperatorKinds.h:21
clang::ento::ObjKind::OS
Indicates that the tracking object is a descendant of a referenced-counted OSObject, used in the Darwin kernel.
clang::ento::allocation_state::markReleased
ProgramStateRef markReleased(ProgramStateRef State, SymbolRef Sym, const Expr *Origin)
Definition: MallocChecker.cpp:3387
clang::ValueDecl::getType
QualType getType() const
Definition: Decl.h:630
clang::Decl::isInStdNamespace
bool isInStdNamespace() const
Definition: DeclBase.cpp:357
CallEvent.h
clang::FunctionDecl::getNumParams
unsigned getNumParams() const
Return the number of parameters this function must have based on its FunctionType.
Definition: Decl.cpp:3242
CallEvent
CheckerContext.h
clang::ento::TypedRegion
TypedRegion - An abstract class representing regions that are typed.
Definition: MemRegion.h:506