clang  7.0.0svn
ObjCSuperDeallocChecker.cpp
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1 //===- ObjCSuperDeallocChecker.cpp - Check correct use of [super dealloc] -===//
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 defines ObjCSuperDeallocChecker, a builtin check that warns when
11 // self is used after a call to [super dealloc] in MRR mode.
12 //
13 //===----------------------------------------------------------------------===//
14 
15 #include "ClangSACheckers.h"
22 
23 using namespace clang;
24 using namespace ento;
25 
26 namespace {
27 class ObjCSuperDeallocChecker
28  : public Checker<check::PostObjCMessage, check::PreObjCMessage,
29  check::PreCall, check::Location> {
30 
31  mutable IdentifierInfo *IIdealloc, *IINSObject;
32  mutable Selector SELdealloc;
33 
34  std::unique_ptr<BugType> DoubleSuperDeallocBugType;
35 
36  void initIdentifierInfoAndSelectors(ASTContext &Ctx) const;
37 
38  bool isSuperDeallocMessage(const ObjCMethodCall &M) const;
39 
40 public:
41  ObjCSuperDeallocChecker();
42  void checkPostObjCMessage(const ObjCMethodCall &M, CheckerContext &C) const;
43  void checkPreObjCMessage(const ObjCMethodCall &M, CheckerContext &C) const;
44 
45  void checkPreCall(const CallEvent &Call, CheckerContext &C) const;
46 
47  void checkLocation(SVal l, bool isLoad, const Stmt *S,
48  CheckerContext &C) const;
49 
50 private:
51 
52  void diagnoseCallArguments(const CallEvent &CE, CheckerContext &C) const;
53 
54  void reportUseAfterDealloc(SymbolRef Sym, StringRef Desc, const Stmt *S,
55  CheckerContext &C) const;
56 };
57 
58 } // End anonymous namespace.
59 
60 // Remember whether [super dealloc] has previously been called on the
61 // SymbolRef for the receiver.
62 REGISTER_SET_WITH_PROGRAMSTATE(CalledSuperDealloc, SymbolRef)
63 
64 namespace {
65 class SuperDeallocBRVisitor final : public BugReporterVisitor {
66  SymbolRef ReceiverSymbol;
67  bool Satisfied;
68 
69 public:
70  SuperDeallocBRVisitor(SymbolRef ReceiverSymbol)
71  : ReceiverSymbol(ReceiverSymbol),
72  Satisfied(false) {}
73 
74  std::shared_ptr<PathDiagnosticPiece> VisitNode(const ExplodedNode *Succ,
75  const ExplodedNode *Pred,
76  BugReporterContext &BRC,
77  BugReport &BR) override;
78 
79  void Profile(llvm::FoldingSetNodeID &ID) const override {
80  ID.Add(ReceiverSymbol);
81  }
82 };
83 } // End anonymous namespace.
84 
85 void ObjCSuperDeallocChecker::checkPreObjCMessage(const ObjCMethodCall &M,
86  CheckerContext &C) const {
87 
89  SymbolRef ReceiverSymbol = M.getReceiverSVal().getAsSymbol();
90  if (!ReceiverSymbol) {
91  diagnoseCallArguments(M, C);
92  return;
93  }
94 
95  bool AlreadyCalled = State->contains<CalledSuperDealloc>(ReceiverSymbol);
96  if (!AlreadyCalled)
97  return;
98 
99  StringRef Desc;
100 
101  if (isSuperDeallocMessage(M)) {
102  Desc = "[super dealloc] should not be called multiple times";
103  } else {
104  Desc = StringRef();
105  }
106 
107  reportUseAfterDealloc(ReceiverSymbol, Desc, M.getOriginExpr(), C);
108 }
109 
110 void ObjCSuperDeallocChecker::checkPreCall(const CallEvent &Call,
111  CheckerContext &C) const {
112  diagnoseCallArguments(Call, C);
113 }
114 
115 void ObjCSuperDeallocChecker::checkPostObjCMessage(const ObjCMethodCall &M,
116  CheckerContext &C) const {
117  // Check for [super dealloc] method call.
118  if (!isSuperDeallocMessage(M))
119  return;
120 
121  ProgramStateRef State = C.getState();
122  SymbolRef ReceiverSymbol = M.getSelfSVal().getAsSymbol();
123  assert(ReceiverSymbol && "No receiver symbol at call to [super dealloc]?");
124 
125  // We add this transition in checkPostObjCMessage to avoid warning when
126  // we inline a call to [super dealloc] where the inlined call itself
127  // calls [super dealloc].
128  State = State->add<CalledSuperDealloc>(ReceiverSymbol);
129  C.addTransition(State);
130 }
131 
132 void ObjCSuperDeallocChecker::checkLocation(SVal L, bool IsLoad, const Stmt *S,
133  CheckerContext &C) const {
134  SymbolRef BaseSym = L.getLocSymbolInBase();
135  if (!BaseSym)
136  return;
137 
138  ProgramStateRef State = C.getState();
139 
140  if (!State->contains<CalledSuperDealloc>(BaseSym))
141  return;
142 
143  const MemRegion *R = L.getAsRegion();
144  if (!R)
145  return;
146 
147  // Climb the super regions to find the base symbol while recording
148  // the second-to-last region for error reporting.
149  const MemRegion *PriorSubRegion = nullptr;
150  while (const SubRegion *SR = dyn_cast<SubRegion>(R)) {
151  if (const SymbolicRegion *SymR = dyn_cast<SymbolicRegion>(SR)) {
152  BaseSym = SymR->getSymbol();
153  break;
154  } else {
155  R = SR->getSuperRegion();
156  PriorSubRegion = SR;
157  }
158  }
159 
160  StringRef Desc = StringRef();
161  auto *IvarRegion = dyn_cast_or_null<ObjCIvarRegion>(PriorSubRegion);
162 
163  std::string Buf;
164  llvm::raw_string_ostream OS(Buf);
165  if (IvarRegion) {
166  OS << "Use of instance variable '" << *IvarRegion->getDecl() <<
167  "' after 'self' has been deallocated";
168  Desc = OS.str();
169  }
170 
171  reportUseAfterDealloc(BaseSym, Desc, S, C);
172 }
173 
174 /// Report a use-after-dealloc on Sym. If not empty,
175 /// Desc will be used to describe the error; otherwise,
176 /// a default warning will be used.
177 void ObjCSuperDeallocChecker::reportUseAfterDealloc(SymbolRef Sym,
178  StringRef Desc,
179  const Stmt *S,
180  CheckerContext &C) const {
181  // We have a use of self after free.
182  // This likely causes a crash, so stop exploring the
183  // path by generating a sink.
184  ExplodedNode *ErrNode = C.generateErrorNode();
185  // If we've already reached this node on another path, return.
186  if (!ErrNode)
187  return;
188 
189  if (Desc.empty())
190  Desc = "Use of 'self' after it has been deallocated";
191 
192  // Generate the report.
193  std::unique_ptr<BugReport> BR(
194  new BugReport(*DoubleSuperDeallocBugType, Desc, ErrNode));
195  BR->addRange(S->getSourceRange());
196  BR->addVisitor(llvm::make_unique<SuperDeallocBRVisitor>(Sym));
197  C.emitReport(std::move(BR));
198 }
199 
200 /// Diagnose if any of the arguments to CE have already been
201 /// dealloc'd.
202 void ObjCSuperDeallocChecker::diagnoseCallArguments(const CallEvent &CE,
203  CheckerContext &C) const {
204  ProgramStateRef State = C.getState();
205  unsigned ArgCount = CE.getNumArgs();
206  for (unsigned I = 0; I < ArgCount; I++) {
207  SymbolRef Sym = CE.getArgSVal(I).getAsSymbol();
208  if (!Sym)
209  continue;
210 
211  if (State->contains<CalledSuperDealloc>(Sym)) {
212  reportUseAfterDealloc(Sym, StringRef(), CE.getArgExpr(I), C);
213  return;
214  }
215  }
216 }
217 
218 ObjCSuperDeallocChecker::ObjCSuperDeallocChecker()
219  : IIdealloc(nullptr), IINSObject(nullptr) {
220 
221  DoubleSuperDeallocBugType.reset(
222  new BugType(this, "[super dealloc] should not be called more than once",
224 }
225 
226 void
227 ObjCSuperDeallocChecker::initIdentifierInfoAndSelectors(ASTContext &Ctx) const {
228  if (IIdealloc)
229  return;
230 
231  IIdealloc = &Ctx.Idents.get("dealloc");
232  IINSObject = &Ctx.Idents.get("NSObject");
233 
234  SELdealloc = Ctx.Selectors.getSelector(0, &IIdealloc);
235 }
236 
237 bool
238 ObjCSuperDeallocChecker::isSuperDeallocMessage(const ObjCMethodCall &M) const {
239  if (M.getOriginExpr()->getReceiverKind() != ObjCMessageExpr::SuperInstance)
240  return false;
241 
242  ASTContext &Ctx = M.getState()->getStateManager().getContext();
243  initIdentifierInfoAndSelectors(Ctx);
244 
245  return M.getSelector() == SELdealloc;
246 }
247 
248 std::shared_ptr<PathDiagnosticPiece>
249 SuperDeallocBRVisitor::VisitNode(const ExplodedNode *Succ,
250  const ExplodedNode *Pred,
251  BugReporterContext &BRC, BugReport &BR) {
252  if (Satisfied)
253  return nullptr;
254 
255  ProgramStateRef State = Succ->getState();
256 
257  bool CalledNow =
258  Succ->getState()->contains<CalledSuperDealloc>(ReceiverSymbol);
259  bool CalledBefore =
260  Pred->getState()->contains<CalledSuperDealloc>(ReceiverSymbol);
261 
262  // Is Succ the node on which the analyzer noted that [super dealloc] was
263  // called on ReceiverSymbol?
264  if (CalledNow && !CalledBefore) {
265  Satisfied = true;
266 
267  ProgramPoint P = Succ->getLocation();
270 
271  if (!L.isValid() || !L.asLocation().isValid())
272  return nullptr;
273 
274  return std::make_shared<PathDiagnosticEventPiece>(
275  L, "[super dealloc] called here");
276  }
277 
278  return nullptr;
279 }
280 
281 //===----------------------------------------------------------------------===//
282 // Checker Registration.
283 //===----------------------------------------------------------------------===//
284 
285 void ento::registerObjCSuperDeallocChecker(CheckerManager &Mgr) {
286  const LangOptions &LangOpts = Mgr.getLangOpts();
287  if (LangOpts.getGC() == LangOptions::GCOnly || LangOpts.ObjCAutoRefCount)
288  return;
289  Mgr.registerChecker<ObjCSuperDeallocChecker>();
290 }
SVal getSelfSVal() const
Return the value of &#39;self&#39; if available.
Definition: CallEvent.cpp:810
SVal getReceiverSVal() const
Returns the value of the receiver at the time of this call.
Definition: CallEvent.cpp:818
const char *const CoreFoundationObjectiveC
Smart pointer class that efficiently represents Objective-C method names.
MemRegion - The root abstract class for all memory regions.
Definition: MemRegion.h:94
ExplodedNode * generateErrorNode(ProgramStateRef State=nullptr, const ProgramPointTag *Tag=nullptr)
Generate a transition to a node that will be used to report an error.
SymbolRef getLocSymbolInBase() const
Get the symbol in the SVal or its base region.
Definition: SVals.cpp:101
Stmt - This represents one statement.
Definition: Stmt.h:66
ExplodedNode * addTransition(ProgramStateRef State=nullptr, const ProgramPointTag *Tag=nullptr)
Generates a new transition in the program state graph (ExplodedGraph).
StringRef P
const ProgramStateRef & getState() const
#define REGISTER_SET_WITH_PROGRAMSTATE(Name, Elem)
Declares an immutable set of type NameTy, suitable for placement into the ProgramState.
Symbolic value.
Definition: SymExpr.h:30
One of these records is kept for each identifier that is lexed.
Holds long-lived AST nodes (such as types and decls) that can be referred to throughout the semantic ...
Definition: ASTContext.h:150
LineState State
virtual const Expr * getArgExpr(unsigned Index) const
Returns the expression associated with a given argument.
Definition: CallEvent.h:298
Keeps track of the various options that can be enabled, which controls the dialect of C or C++ that i...
Definition: LangOptions.h:50
IdentifierTable & Idents
Definition: ASTContext.h:539
Represents any expression that calls an Objective-C method.
Definition: CallEvent.h:892
SymbolRef getAsSymbol(bool IncludeBaseRegions=false) const
If this SVal wraps a symbol return that SymbolRef.
Definition: SVals.cpp:127
SymbolicRegion - A special, "non-concrete" region.
Definition: MemRegion.h:759
ReceiverKind getReceiverKind() const
Determine the kind of receiver that this message is being sent to.
Definition: ExprObjC.h:1187
CHECKER * registerChecker(AT... Args)
Used to register checkers.
void emitReport(std::unique_ptr< BugReport > R)
Emit the diagnostics report.
#define false
Definition: stdbool.h:33
SelectorTable & Selectors
Definition: ASTContext.h:540
IdentifierInfo & get(StringRef Name)
Return the identifier token info for the specified named identifier.
const MemRegion * getAsRegion() const
Definition: SVals.cpp:151
ProgramPoint getLocation() const
getLocation - Returns the edge associated with the given node.
SVal - This represents a symbolic expression, which can be either an L-value or an R-value...
Definition: SVals.h:76
virtual const ObjCMessageExpr * getOriginExpr() const
Definition: CallEvent.h:916
Selector getSelector() const
Definition: CallEvent.h:940
Dataflow Directional Tag Classes.
bool isValid() const
Return true if this is a valid SourceLocation object.
std::unique_ptr< DiagnosticConsumer > create(StringRef OutputFile, DiagnosticOptions *Diags, bool MergeChildRecords=false)
Returns a DiagnosticConsumer that serializes diagnostics to a bitcode file.
Represents an abstract call to a function or method along a particular path.
Definition: CallEvent.h:164
SubRegion - A region that subsets another larger region.
Definition: MemRegion.h:431
const ProgramStateRef & getState() const
Selector getSelector(unsigned NumArgs, IdentifierInfo **IIV)
Can create any sort of selector.
virtual unsigned getNumArgs() const =0
Returns the number of arguments (explicit and implicit).
SourceRange getSourceRange() const LLVM_READONLY
SourceLocation tokens are not useful in isolation - they are low level value objects created/interpre...
Definition: Stmt.cpp:266
virtual SVal getArgSVal(unsigned Index) const
Returns the value of a given argument at the time of the call.
Definition: CallEvent.cpp:268
This class provides an interface through which checkers can create individual bug reports...
Definition: BugReporter.h:76
const LangOptions & getLangOpts() const
SourceManager & getSourceManager()
Definition: BugReporter.h:585