clang 8.0.0

InnerPointerChecker.cpp
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1 //=== InnerPointerChecker.cpp -------------------------------------*- C++ -*--//
2 //
3 // The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
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.
13 //
14 //===----------------------------------------------------------------------===//
15
16 #include "AllocationState.h"
17 #include "clang/StaticAnalyzer/Checkers/BuiltinCheckerRegistration.h"
18 #include "InterCheckerAPI.h"
19 #include "clang/StaticAnalyzer/Core/BugReporter/BugType.h"
20 #include "clang/StaticAnalyzer/Core/BugReporter/CommonBugCategories.h"
21 #include "clang/StaticAnalyzer/Core/Checker.h"
22 #include "clang/StaticAnalyzer/Core/PathSensitive/CallEvent.h"
23 #include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
24
25 using namespace clang;
26 using namespace ento;
27
28 // Associate container objects with a set of raw pointer symbols.
29 REGISTER_SET_FACTORY_WITH_PROGRAMSTATE(PtrSet, SymbolRef)
30 REGISTER_MAP_WITH_PROGRAMSTATE(RawPtrMap, const MemRegion *, PtrSet)
31
32
33 namespace {
34
35 class InnerPointerChecker
36 : public Checker<check::DeadSymbols, check::PostCall> {
37
38 CallDescription AppendFn, AssignFn, ClearFn, CStrFn, DataFn, EraseFn,
39 InsertFn, PopBackFn, PushBackFn, ReplaceFn, ReserveFn, ResizeFn,
40 ShrinkToFitFn, SwapFn;
41
42 public:
43 class InnerPointerBRVisitor : public BugReporterVisitor {
44 SymbolRef PtrToBuf;
45
46 public:
47 InnerPointerBRVisitor(SymbolRef Sym) : PtrToBuf(Sym) {}
48
49 static void *getTag() {
50 static int Tag = 0;
51 return &Tag;
52 }
53
54 void Profile(llvm::FoldingSetNodeID &ID) const override {
55 ID.AddPointer(getTag());
56 }
57
58 virtual std::shared_ptr<PathDiagnosticPiece> VisitNode(const ExplodedNode *N,
59 BugReporterContext &BRC,
60 BugReport &BR) override;
61
62 // FIXME: Scan the map once in the visitor's constructor and do a direct
63 // lookup by region.
64 bool isSymbolTracked(ProgramStateRef State, SymbolRef Sym) {
65 RawPtrMapTy Map = State->get<RawPtrMap>();
66 for (const auto Entry : Map) {
67 if (Entry.second.contains(Sym))
68 return true;
69 }
70 return false;
71 }
72 };
73
74 InnerPointerChecker()
75 : AppendFn({"std", "basic_string", "append"}),
76 AssignFn({"std", "basic_string", "assign"}),
77 ClearFn({"std", "basic_string", "clear"}),
78 CStrFn({"std", "basic_string", "c_str"}),
79 DataFn({"std", "basic_string", "data"}),
80 EraseFn({"std", "basic_string", "erase"}),
81 InsertFn({"std", "basic_string", "insert"}),
82 PopBackFn({"std", "basic_string", "pop_back"}),
83 PushBackFn({"std", "basic_string", "push_back"}),
84 ReplaceFn({"std", "basic_string", "replace"}),
85 ReserveFn({"std", "basic_string", "reserve"}),
86 ResizeFn({"std", "basic_string", "resize"}),
87 ShrinkToFitFn({"std", "basic_string", "shrink_to_fit"}),
88 SwapFn({"std", "basic_string", "swap"}) {}
89
90 /// Check whether the called member function potentially invalidates
91 /// pointers referring to the container object's inner buffer.
92 bool isInvalidatingMemberFunction(const CallEvent &Call) const;
93
94 /// Mark pointer symbols associated with the given memory region released
95 /// in the program state.
96 void markPtrSymbolsReleased(const CallEvent &Call, ProgramStateRef State,
97 const MemRegion *ObjRegion,
98 CheckerContext &C) const;
99
100 /// Standard library functions that take a non-const `basic_string` argument by
101 /// reference may invalidate its inner pointers. Check for these cases and
102 /// mark the pointers released.
103 void checkFunctionArguments(const CallEvent &Call, ProgramStateRef State,
104 CheckerContext &C) const;
105
106 /// Record the connection between raw pointers referring to a container
107 /// object's inner buffer and the object's memory region in the program state.
108 /// Mark potentially invalidated pointers released.
109 void checkPostCall(const CallEvent &Call, CheckerContext &C) const;
110
111 /// Clean up the program state map.
112 void checkDeadSymbols(SymbolReaper &SymReaper, CheckerContext &C) const;
113 };
114
115 } // end anonymous namespace
116
117 bool InnerPointerChecker::isInvalidatingMemberFunction(
118 const CallEvent &Call) const {
119 if (const auto *MemOpCall = dyn_cast<CXXMemberOperatorCall>(&Call)) {
120 OverloadedOperatorKind Opc = MemOpCall->getOriginExpr()->getOperator();
121 if (Opc == OO_Equal || Opc == OO_PlusEqual)
122 return true;
123 return false;
124 }
125 return (isa<CXXDestructorCall>(Call) || Call.isCalled(AppendFn) ||
126 Call.isCalled(AssignFn) || Call.isCalled(ClearFn) ||
127 Call.isCalled(EraseFn) || Call.isCalled(InsertFn) ||
128 Call.isCalled(PopBackFn) || Call.isCalled(PushBackFn) ||
129 Call.isCalled(ReplaceFn) || Call.isCalled(ReserveFn) ||
130 Call.isCalled(ResizeFn) || Call.isCalled(ShrinkToFitFn) ||
131 Call.isCalled(SwapFn));
132 }
133
134 void InnerPointerChecker::markPtrSymbolsReleased(const CallEvent &Call,
135 ProgramStateRef State,
136 const MemRegion *MR,
137 CheckerContext &C) const {
138 if (const PtrSet *PS = State->get<RawPtrMap>(MR)) {
139 const Expr *Origin = Call.getOriginExpr();
140 for (const auto Symbol : *PS) {
141 // NOTE: `Origin` may be null, and will be stored so in the symbol's
142 // `RefState` in MallocChecker's `RegionState` program state map.
143 State = allocation_state::markReleased(State, Symbol, Origin);
144 }
145 State = State->remove<RawPtrMap>(MR);
146 C.addTransition(State);
147 return;
148 }
149 }
150
151 void InnerPointerChecker::checkFunctionArguments(const CallEvent &Call,
152 ProgramStateRef State,
153 CheckerContext &C) const {
154 if (const auto *FC = dyn_cast<AnyFunctionCall>(&Call)) {
155 const FunctionDecl *FD = FC->getDecl();
156 if (!FD || !FD->isInStdNamespace())
157 return;
158
159 for (unsigned I = 0, E = FD->getNumParams(); I != E; ++I) {
160 QualType ParamTy = FD->getParamDecl(I)->getType();
161 if (!ParamTy->isReferenceType() ||
162 ParamTy->getPointeeType().isConstQualified())
163 continue;
164
165 // In case of member operator calls, `this` is counted as an
166 // argument but not as a parameter.
167 bool isaMemberOpCall = isa<CXXMemberOperatorCall>(FC);
168 unsigned ArgI = isaMemberOpCall ? I+1 : I;
169
170 SVal Arg = FC->getArgSVal(ArgI);
171 const auto *ArgRegion =
172 dyn_cast_or_null<TypedValueRegion>(Arg.getAsRegion());
173 if (!ArgRegion)
174 continue;
175
176 markPtrSymbolsReleased(Call, State, ArgRegion, C);
177 }
178 }
179 }
180
181 // [string.require]
182 //
183 // "References, pointers, and iterators referring to the elements of a
184 // basic_string sequence may be invalidated by the following uses of that
185 // basic_string object:
186 //
187 // -- As an argument to any standard library function taking a reference
188 // to non-const basic_string as an argument. For example, as an argument to
189 // non-member functions swap(), operator>>(), and getline(), or as an argument
190 // to basic_string::swap().
191 //
192 // -- Calling non-const member functions, except operator[], at, front, back,
193 // begin, rbegin, end, and rend."
194
195 void InnerPointerChecker::checkPostCall(const CallEvent &Call,
196 CheckerContext &C) const {
197 ProgramStateRef State = C.getState();
198
199 if (const auto *ICall = dyn_cast<CXXInstanceCall>(&Call)) {
200 // TODO: Do we need these to be typed?
201 const auto *ObjRegion = dyn_cast_or_null<TypedValueRegion>(
202 ICall->getCXXThisVal().getAsRegion());
203 if (!ObjRegion)
204 return;
205
206 if (Call.isCalled(CStrFn) || Call.isCalled(DataFn)) {
207 SVal RawPtr = Call.getReturnValue();
208 if (SymbolRef Sym = RawPtr.getAsSymbol(/*IncludeBaseRegions=*/true)) {
209 // Start tracking this raw pointer by adding it to the set of symbols
210 // associated with this container object in the program state map.
211
212 PtrSet::Factory &F = State->getStateManager().get_context<PtrSet>();
213 const PtrSet *SetPtr = State->get<RawPtrMap>(ObjRegion);
214 PtrSet Set = SetPtr ? *SetPtr : F.getEmptySet();
215 assert(C.wasInlined || !Set.contains(Sym));
216 Set = F.add(Set, Sym);
217
218 State = State->set<RawPtrMap>(ObjRegion, Set);
219 C.addTransition(State);
220 }
221 return;
222 }
223
224 // Check [string.require] / second point.
225 if (isInvalidatingMemberFunction(Call)) {
226 markPtrSymbolsReleased(Call, State, ObjRegion, C);
227 return;
228 }
229 }
230
231 // Check [string.require] / first point.
232 checkFunctionArguments(Call, State, C);
233 }
234
235 void InnerPointerChecker::checkDeadSymbols(SymbolReaper &SymReaper,
236 CheckerContext &C) const {
237 ProgramStateRef State = C.getState();
238 PtrSet::Factory &F = State->getStateManager().get_context<PtrSet>();
239 RawPtrMapTy RPM = State->get<RawPtrMap>();
240 for (const auto Entry : RPM) {
241 if (!SymReaper.isLiveRegion(Entry.first)) {
242 // Due to incomplete destructor support, some dead regions might
243 // remain in the program state map. Clean them up.
244 State = State->remove<RawPtrMap>(Entry.first);
245 }
246 if (const PtrSet *OldSet = State->get<RawPtrMap>(Entry.first)) {
247 PtrSet CleanedUpSet = *OldSet;
248 for (const auto Symbol : Entry.second) {
249 if (!SymReaper.isLive(Symbol))
250 CleanedUpSet = F.remove(CleanedUpSet, Symbol);
251 }
252 State = CleanedUpSet.isEmpty()
253 ? State->remove<RawPtrMap>(Entry.first)
254 : State->set<RawPtrMap>(Entry.first, CleanedUpSet);
255 }
256 }
257 C.addTransition(State);
258 }
259
260 namespace clang {
261 namespace ento {
262 namespace allocation_state {
263
264 std::unique_ptr<BugReporterVisitor> getInnerPointerBRVisitor(SymbolRef Sym) {
265 return llvm::make_unique<InnerPointerChecker::InnerPointerBRVisitor>(Sym);
266 }
267
268 const MemRegion *getContainerObjRegion(ProgramStateRef State, SymbolRef Sym) {
269 RawPtrMapTy Map = State->get<RawPtrMap>();
270 for (const auto Entry : Map) {
271 if (Entry.second.contains(Sym)) {
272 return Entry.first;
273 }
274 }
275 return nullptr;
276 }
277
278 } // end namespace allocation_state
279 } // end namespace ento
280 } // end namespace clang
281
282 std::shared_ptr<PathDiagnosticPiece>
283 InnerPointerChecker::InnerPointerBRVisitor::VisitNode(const ExplodedNode *N,
284 BugReporterContext &BRC,
285 BugReport &) {
286 if (!isSymbolTracked(N->getState(), PtrToBuf) ||
287 isSymbolTracked(N->getFirstPred()->getState(), PtrToBuf))
288 return nullptr;
289
290 const Stmt *S = PathDiagnosticLocation::getStmt(N);
291 if (!S)
292 return nullptr;
293
294 const MemRegion *ObjRegion =
295 allocation_state::getContainerObjRegion(N->getState(), PtrToBuf);
296 const auto *TypedRegion = cast<TypedValueRegion>(ObjRegion);
297 QualType ObjTy = TypedRegion->getValueType();
298
299 SmallString<256> Buf;
300 llvm::raw_svector_ostream OS(Buf);
301 OS << "Pointer to inner buffer of '" << ObjTy.getAsString()
302 << "' obtained here";
303 PathDiagnosticLocation Pos(S, BRC.getSourceManager(),
304 N->getLocationContext());
305 return std::make_shared<PathDiagnosticEventPiece>(Pos, OS.str(), true,
306 nullptr);
307 }
308
309 void ento::registerInnerPointerChecker(CheckerManager &Mgr) {
310 registerInnerPointerCheckerAux(Mgr);
311 Mgr.registerChecker<InnerPointerChecker>();
312 }
clang::Builtin::ID
ID
Definition: Builtins.h:49
ento
clang::FunctionDecl
Represents a function declaration or definition.
Definition: Decl.h:1738
clang::QualType
A (possibly-)qualified type.
Definition: Type.h:638
clang::ento::MemRegion
MemRegion - The root abstract class for all memory regions.
Definition: MemRegion.h:95
clang::ento::SymbolRef
const SymExpr * SymbolRef
Definition: PathDiagnostic.h:59
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:505
clang::ento::registerInnerPointerCheckerAux
void registerInnerPointerCheckerAux(CheckerManager &Mgr)
Register the part of MallocChecker connected to InnerPointerChecker.
Definition: MallocChecker.cpp:3111
clang::ento::ProgramStateRef
IntrusiveRefCntPtr< const ProgramState > ProgramStateRef
Definition: ProgramState_Fwd.h:38
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:268
BugType.h
clang::ento::ExplodedNode::getState
const ProgramStateRef & getState() const
Definition: ExplodedGraph.h:164
clang::ento::CheckerManager
Definition: CheckerManager.h:117
AllocationState.h
BugReporterVisitor
clang::ento::SymExpr
Symbolic value.
Definition: SymExpr.h:30
State
LineState State
Definition: UnwrappedLineFormatter.cpp:877
clang::ento::PathDiagnosticLocation
Definition: PathDiagnostic.h:156
Checker.h
clang::Type::isReferenceType
bool isReferenceType() const
Definition: Type.h:6308
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:264
clang::ento::ExplodedNode
Definition: ExplodedGraph.h:66
clang::ento::ExplodedNode::getLocationContext
const LocationContext * getLocationContext() const
Definition: ExplodedGraph.h:145
clang::ento::ExplodedNode::getFirstPred
ExplodedNode * getFirstPred()
Definition: ExplodedGraph.h:205
llvm::SmallString
Definition: LLVM.h:35
clang::Expr
This represents one expression.
Definition: Expr.h:106
clang::ento::BugReporterContext
Definition: BugReporter.h:557
CommonBugCategories.h
BuiltinCheckerRegistration.h
clang::QualType::isConstQualified
bool isConstQualified() const
Determine whether this type is const-qualified.
Definition: Type.h:6131
clang::ento::PathDiagnosticLocation::getStmt
static const Stmt * getStmt(const ExplodedNode *N)
Given an exploded node, retrieve the statement that should be used for the diagnostic location...
Definition: PathDiagnostic.cpp:767
llvm::IntrusiveRefCntPtr
Definition: LLVM.h:45
clang::ento::CheckerManager::registerChecker
CHECKER * registerChecker(AT &&... Args)
Used to register checkers.
Definition: CheckerManager.h:154
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:85
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:117
clang::FunctionDecl::getParamDecl
const ParmVarDecl * getParamDecl(unsigned i) const
Definition: Decl.h:2285
clang
Dataflow Directional Tag Classes.
Definition: CFGReachabilityAnalysis.h:22
InterCheckerAPI.h
clang::OverloadedOperatorKind
OverloadedOperatorKind
Enumeration specifying the different kinds of C++ overloaded operators.
Definition: OperatorKinds.h:22
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:3081
clang::ValueDecl::getType
QualType getType() const
Definition: Decl.h:648
clang::ento::BugReport
This class provides an interface through which checkers can create individual bug reports...
Definition: BugReporter.h:76
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:3055
CallEvent
CheckerContext.h
clang::ento::BugReporterContext::getSourceManager
SourceManager & getSourceManager()
Definition: BugReporter.h:585
clang::ento::TypedRegion
TypedRegion - An abstract class representing regions that are typed.
Definition: MemRegion.h:506