MallocChecker.cpp revision 07d39a479cf8f20294407e749f9933da34ebecb7 
1//=== MallocChecker.cpp - A malloc/free checker -------------------*- 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 malloc/free checker, which checks for potential memory
11// leaks, double free, and use-after-free problems.
12//
13//===----------------------------------------------------------------------===//
14
15#include "ClangSACheckers.h"
16#include "InterCheckerAPI.h"
17#include "clang/StaticAnalyzer/Core/Checker.h"
18#include "clang/StaticAnalyzer/Core/CheckerManager.h"
19#include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
20#include "clang/StaticAnalyzer/Core/BugReporter/BugType.h"
21#include "clang/StaticAnalyzer/Core/PathSensitive/ObjCMessage.h"
22#include "clang/StaticAnalyzer/Core/PathSensitive/ProgramState.h"
23#include "clang/StaticAnalyzer/Core/PathSensitive/ProgramStateTrait.h"
24#include "clang/StaticAnalyzer/Core/PathSensitive/SymbolManager.h"
25#include "clang/Basic/SourceManager.h"
26#include "llvm/ADT/ImmutableMap.h"
27#include "llvm/ADT/SmallString.h"
28#include "llvm/ADT/STLExtras.h"
29#include <climits>
30
31using namespace clang;
32using namespace ento;
33
34namespace {
35
36class RefState {
37  enum Kind { AllocateUnchecked, AllocateFailed, Released, Escaped,
38              Relinquished } K;
39  const Stmt *S;
40
41public:
42  RefState(Kind k, const Stmt *s) : K(k), S(s) {}
43
44  bool isAllocated() const { return K == AllocateUnchecked; }
45  //bool isFailed() const { return K == AllocateFailed; }
46  bool isReleased() const { return K == Released; }
47  //bool isEscaped() const { return K == Escaped; }
48  //bool isRelinquished() const { return K == Relinquished; }
49  const Stmt *getStmt() const { return S; }
50
51  bool operator==(const RefState &X) const {
52    return K == X.K && S == X.S;
53  }
54
55  static RefState getAllocateUnchecked(const Stmt *s) {
56    return RefState(AllocateUnchecked, s);
57  }
58  static RefState getAllocateFailed() {
59    return RefState(AllocateFailed, 0);
60  }
61  static RefState getReleased(const Stmt *s) { return RefState(Released, s); }
62  static RefState getEscaped(const Stmt *s) { return RefState(Escaped, s); }
63  static RefState getRelinquished(const Stmt *s) {
64    return RefState(Relinquished, s);
65  }
66
67  void Profile(llvm::FoldingSetNodeID &ID) const {
68    ID.AddInteger(K);
69    ID.AddPointer(S);
70  }
71};
72
73struct ReallocPair {
74  SymbolRef ReallocatedSym;
75  bool IsFreeOnFailure;
76  ReallocPair(SymbolRef S, bool F) : ReallocatedSym(S), IsFreeOnFailure(F) {}
77  void Profile(llvm::FoldingSetNodeID &ID) const {
78    ID.AddInteger(IsFreeOnFailure);
79    ID.AddPointer(ReallocatedSym);
80  }
81  bool operator==(const ReallocPair &X) const {
82    return ReallocatedSym == X.ReallocatedSym &&
83           IsFreeOnFailure == X.IsFreeOnFailure;
84  }
85};
86
87class MallocChecker : public Checker<check::DeadSymbols,
88                                     check::EndPath,
89                                     check::PreStmt<ReturnStmt>,
90                                     check::PreStmt<CallExpr>,
91                                     check::PostStmt<CallExpr>,
92                                     check::Location,
93                                     check::Bind,
94                                     eval::Assume,
95                                     check::RegionChanges>
96{
97  mutable OwningPtr<BugType> BT_DoubleFree;
98  mutable OwningPtr<BugType> BT_Leak;
99  mutable OwningPtr<BugType> BT_UseFree;
100  mutable OwningPtr<BugType> BT_BadFree;
101  mutable IdentifierInfo *II_malloc, *II_free, *II_realloc, *II_calloc,
102                         *II_valloc, *II_reallocf, *II_strndup, *II_strdup;
103
104  static const unsigned InvalidArgIndex = UINT_MAX;
105
106public:
107  MallocChecker() : II_malloc(0), II_free(0), II_realloc(0), II_calloc(0),
108                    II_valloc(0), II_reallocf(0), II_strndup(0), II_strdup(0) {}
109
110  /// In pessimistic mode, the checker assumes that it does not know which
111  /// functions might free the memory.
112  struct ChecksFilter {
113    DefaultBool CMallocPessimistic;
114    DefaultBool CMallocOptimistic;
115  };
116
117  ChecksFilter Filter;
118
119  void checkPreStmt(const CallExpr *S, CheckerContext &C) const;
120  void checkPostStmt(const CallExpr *CE, CheckerContext &C) const;
121  void checkDeadSymbols(SymbolReaper &SymReaper, CheckerContext &C) const;
122  void checkEndPath(CheckerContext &C) const;
123  void checkPreStmt(const ReturnStmt *S, CheckerContext &C) const;
124  ProgramStateRef evalAssume(ProgramStateRef state, SVal Cond,
125                            bool Assumption) const;
126  void checkLocation(SVal l, bool isLoad, const Stmt *S,
127                     CheckerContext &C) const;
128  void checkBind(SVal location, SVal val, const Stmt*S,
129                 CheckerContext &C) const;
130  ProgramStateRef
131  checkRegionChanges(ProgramStateRef state,
132                     const StoreManager::InvalidatedSymbols *invalidated,
133                     ArrayRef<const MemRegion *> ExplicitRegions,
134                     ArrayRef<const MemRegion *> Regions,
135                     const CallOrObjCMessage *Call) const;
136  bool wantsRegionChangeUpdate(ProgramStateRef state) const {
137    return true;
138  }
139
140private:
141  void initIdentifierInfo(ASTContext &C) const;
142
143  /// Check if this is one of the functions which can allocate/reallocate memory
144  /// pointed to by one of its arguments.
145  bool isMemFunction(const FunctionDecl *FD, ASTContext &C) const;
146
147  static ProgramStateRef MallocMemReturnsAttr(CheckerContext &C,
148                                              const CallExpr *CE,
149                                              const OwnershipAttr* Att);
150  static ProgramStateRef MallocMemAux(CheckerContext &C, const CallExpr *CE,
151                                     const Expr *SizeEx, SVal Init,
152                                     ProgramStateRef state) {
153    return MallocMemAux(C, CE,
154                        state->getSVal(SizeEx, C.getLocationContext()),
155                        Init, state);
156  }
157
158  static ProgramStateRef MallocMemAux(CheckerContext &C, const CallExpr *CE,
159                                     SVal SizeEx, SVal Init,
160                                     ProgramStateRef state);
161
162  /// Update the RefState to reflect the new memory allocation.
163  static ProgramStateRef MallocUpdateRefState(CheckerContext &C,
164                                              const CallExpr *CE,
165                                              ProgramStateRef state);
166
167  ProgramStateRef FreeMemAttr(CheckerContext &C, const CallExpr *CE,
168                              const OwnershipAttr* Att) const;
169  ProgramStateRef FreeMemAux(CheckerContext &C, const CallExpr *CE,
170                                 ProgramStateRef state, unsigned Num,
171                                 bool Hold) const;
172
173  ProgramStateRef ReallocMem(CheckerContext &C, const CallExpr *CE,
174                             bool FreesMemOnFailure) const;
175  static ProgramStateRef CallocMem(CheckerContext &C, const CallExpr *CE);
176
177  bool checkEscape(SymbolRef Sym, const Stmt *S, CheckerContext &C) const;
178  bool checkUseAfterFree(SymbolRef Sym, CheckerContext &C,
179                         const Stmt *S = 0) const;
180
181  /// Check if the function is not known to us. So, for example, we could
182  /// conservatively assume it can free/reallocate it's pointer arguments.
183  bool doesNotFreeMemory(const CallOrObjCMessage *Call,
184                         ProgramStateRef State) const;
185
186  static bool SummarizeValue(raw_ostream &os, SVal V);
187  static bool SummarizeRegion(raw_ostream &os, const MemRegion *MR);
188  void ReportBadFree(CheckerContext &C, SVal ArgVal, SourceRange range) const;
189
190  /// Find the location of the allocation for Sym on the path leading to the
191  /// exploded node N.
192  const Stmt *getAllocationSite(const ExplodedNode *N, SymbolRef Sym,
193                                CheckerContext &C) const;
194
195  void reportLeak(SymbolRef Sym, ExplodedNode *N, CheckerContext &C) const;
196
197  /// The bug visitor which allows us to print extra diagnostics along the
198  /// BugReport path. For example, showing the allocation site of the leaked
199  /// region.
200  class MallocBugVisitor : public BugReporterVisitor {
201  protected:
202    enum NotificationMode {
203      Normal,
204      Complete,
205      ReallocationFailed
206    };
207
208    // The allocated region symbol tracked by the main analysis.
209    SymbolRef Sym;
210    NotificationMode Mode;
211
212  public:
213    MallocBugVisitor(SymbolRef S) : Sym(S), Mode(Normal) {}
214    virtual ~MallocBugVisitor() {}
215
216    void Profile(llvm::FoldingSetNodeID &ID) const {
217      static int X = 0;
218      ID.AddPointer(&X);
219      ID.AddPointer(Sym);
220    }
221
222    inline bool isAllocated(const RefState *S, const RefState *SPrev,
223                            const Stmt *Stmt) {
224      // Did not track -> allocated. Other state (released) -> allocated.
225      return (Stmt && isa<CallExpr>(Stmt) &&
226              (S && S->isAllocated()) && (!SPrev || !SPrev->isAllocated()));
227    }
228
229    inline bool isReleased(const RefState *S, const RefState *SPrev,
230                           const Stmt *Stmt) {
231      // Did not track -> released. Other state (allocated) -> released.
232      return (Stmt && isa<CallExpr>(Stmt) &&
233              (S && S->isReleased()) && (!SPrev || !SPrev->isReleased()));
234    }
235
236    inline bool isReallocFailedCheck(const RefState *S, const RefState *SPrev,
237                                     const Stmt *Stmt) {
238      // If the expression is not a call, and the state change is
239      // released -> allocated, it must be the realloc return value
240      // check. If we have to handle more cases here, it might be cleaner just
241      // to track this extra bit in the state itself.
242      return ((!Stmt || !isa<CallExpr>(Stmt)) &&
243              (S && S->isAllocated()) && (SPrev && !SPrev->isAllocated()));
244    }
245
246    PathDiagnosticPiece *VisitNode(const ExplodedNode *N,
247                                   const ExplodedNode *PrevN,
248                                   BugReporterContext &BRC,
249                                   BugReport &BR);
250  };
251};
252} // end anonymous namespace
253
254typedef llvm::ImmutableMap<SymbolRef, RefState> RegionStateTy;
255typedef llvm::ImmutableMap<SymbolRef, ReallocPair > ReallocMap;
256class RegionState {};
257class ReallocPairs {};
258namespace clang {
259namespace ento {
260  template <>
261  struct ProgramStateTrait<RegionState>
262    : public ProgramStatePartialTrait<RegionStateTy> {
263    static void *GDMIndex() { static int x; return &x; }
264  };
265
266  template <>
267  struct ProgramStateTrait<ReallocPairs>
268    : public ProgramStatePartialTrait<ReallocMap> {
269    static void *GDMIndex() { static int x; return &x; }
270  };
271}
272}
273
274namespace {
275class StopTrackingCallback : public SymbolVisitor {
276  ProgramStateRef state;
277public:
278  StopTrackingCallback(ProgramStateRef st) : state(st) {}
279  ProgramStateRef getState() const { return state; }
280
281  bool VisitSymbol(SymbolRef sym) {
282    state = state->remove<RegionState>(sym);
283    return true;
284  }
285};
286} // end anonymous namespace
287
288void MallocChecker::initIdentifierInfo(ASTContext &Ctx) const {
289  if (!II_malloc)
290    II_malloc = &Ctx.Idents.get("malloc");
291  if (!II_free)
292    II_free = &Ctx.Idents.get("free");
293  if (!II_realloc)
294    II_realloc = &Ctx.Idents.get("realloc");
295  if (!II_reallocf)
296    II_reallocf = &Ctx.Idents.get("reallocf");
297  if (!II_calloc)
298    II_calloc = &Ctx.Idents.get("calloc");
299  if (!II_valloc)
300    II_valloc = &Ctx.Idents.get("valloc");
301  if (!II_strdup)
302    II_strdup = &Ctx.Idents.get("strdup");
303  if (!II_strndup)
304    II_strndup = &Ctx.Idents.get("strndup");
305}
306
307bool MallocChecker::isMemFunction(const FunctionDecl *FD, ASTContext &C) const {
308  if (!FD)
309    return false;
310  IdentifierInfo *FunI = FD->getIdentifier();
311  if (!FunI)
312    return false;
313
314  initIdentifierInfo(C);
315
316  if (FunI == II_malloc || FunI == II_free || FunI == II_realloc ||
317      FunI == II_reallocf || FunI == II_calloc || FunI == II_valloc ||
318      FunI == II_strdup || FunI == II_strndup)
319    return true;
320
321  if (Filter.CMallocOptimistic && FD->hasAttrs() &&
322      FD->specific_attr_begin<OwnershipAttr>() !=
323          FD->specific_attr_end<OwnershipAttr>())
324    return true;
325
326
327  return false;
328}
329
330void MallocChecker::checkPostStmt(const CallExpr *CE, CheckerContext &C) const {
331  const FunctionDecl *FD = C.getCalleeDecl(CE);
332  if (!FD)
333    return;
334
335  initIdentifierInfo(C.getASTContext());
336  IdentifierInfo *FunI = FD->getIdentifier();
337  if (!FunI)
338    return;
339
340  ProgramStateRef State = C.getState();
341  if (FunI == II_malloc || FunI == II_valloc) {
342    State = MallocMemAux(C, CE, CE->getArg(0), UndefinedVal(), State);
343  } else if (FunI == II_realloc) {
344    State = ReallocMem(C, CE, false);
345  } else if (FunI == II_reallocf) {
346    State = ReallocMem(C, CE, true);
347  } else if (FunI == II_calloc) {
348    State = CallocMem(C, CE);
349  } else if (FunI == II_free) {
350    State = FreeMemAux(C, CE, C.getState(), 0, false);
351  } else if (FunI == II_strdup) {
352    State = MallocUpdateRefState(C, CE, State);
353  } else if (FunI == II_strndup) {
354    State = MallocUpdateRefState(C, CE, State);
355  } else if (Filter.CMallocOptimistic) {
356    // Check all the attributes, if there are any.
357    // There can be multiple of these attributes.
358    if (FD->hasAttrs())
359      for (specific_attr_iterator<OwnershipAttr>
360          i = FD->specific_attr_begin<OwnershipAttr>(),
361          e = FD->specific_attr_end<OwnershipAttr>();
362          i != e; ++i) {
363        switch ((*i)->getOwnKind()) {
364        case OwnershipAttr::Returns:
365          State = MallocMemReturnsAttr(C, CE, *i);
366          break;
367        case OwnershipAttr::Takes:
368        case OwnershipAttr::Holds:
369          State = FreeMemAttr(C, CE, *i);
370          break;
371        }
372      }
373  }
374  C.addTransition(State);
375}
376
377ProgramStateRef MallocChecker::MallocMemReturnsAttr(CheckerContext &C,
378                                                    const CallExpr *CE,
379                                                    const OwnershipAttr* Att) {
380  if (Att->getModule() != "malloc")
381    return 0;
382
383  OwnershipAttr::args_iterator I = Att->args_begin(), E = Att->args_end();
384  if (I != E) {
385    return MallocMemAux(C, CE, CE->getArg(*I), UndefinedVal(), C.getState());
386  }
387  return MallocMemAux(C, CE, UnknownVal(), UndefinedVal(), C.getState());
388}
389
390ProgramStateRef MallocChecker::MallocMemAux(CheckerContext &C,
391                                           const CallExpr *CE,
392                                           SVal Size, SVal Init,
393                                           ProgramStateRef state) {
394  // Get the return value.
395  SVal retVal = state->getSVal(CE, C.getLocationContext());
396
397  // We expect the malloc functions to return a pointer.
398  if (!isa<Loc>(retVal))
399    return 0;
400
401  // Fill the region with the initialization value.
402  state = state->bindDefault(retVal, Init);
403
404  // Set the region's extent equal to the Size parameter.
405  const SymbolicRegion *R =
406      dyn_cast_or_null<SymbolicRegion>(retVal.getAsRegion());
407  if (!R)
408    return 0;
409  if (isa<DefinedOrUnknownSVal>(Size)) {
410    SValBuilder &svalBuilder = C.getSValBuilder();
411    DefinedOrUnknownSVal Extent = R->getExtent(svalBuilder);
412    DefinedOrUnknownSVal DefinedSize = cast<DefinedOrUnknownSVal>(Size);
413    DefinedOrUnknownSVal extentMatchesSize =
414        svalBuilder.evalEQ(state, Extent, DefinedSize);
415
416    state = state->assume(extentMatchesSize, true);
417    assert(state);
418  }
419
420  return MallocUpdateRefState(C, CE, state);
421}
422
423ProgramStateRef MallocChecker::MallocUpdateRefState(CheckerContext &C,
424                                                    const CallExpr *CE,
425                                                    ProgramStateRef state) {
426  // Get the return value.
427  SVal retVal = state->getSVal(CE, C.getLocationContext());
428
429  // We expect the malloc functions to return a pointer.
430  if (!isa<Loc>(retVal))
431    return 0;
432
433  SymbolRef Sym = retVal.getAsLocSymbol();
434  assert(Sym);
435
436  // Set the symbol's state to Allocated.
437  return state->set<RegionState>(Sym, RefState::getAllocateUnchecked(CE));
438
439}
440
441ProgramStateRef MallocChecker::FreeMemAttr(CheckerContext &C,
442                                           const CallExpr *CE,
443                                           const OwnershipAttr* Att) const {
444  if (Att->getModule() != "malloc")
445    return 0;
446
447  for (OwnershipAttr::args_iterator I = Att->args_begin(), E = Att->args_end();
448       I != E; ++I) {
449    return FreeMemAux(C, CE, C.getState(), *I,
450                      Att->getOwnKind() == OwnershipAttr::Holds);
451  }
452  return 0;
453}
454
455ProgramStateRef MallocChecker::FreeMemAux(CheckerContext &C,
456                                          const CallExpr *CE,
457                                          ProgramStateRef state,
458                                          unsigned Num,
459                                          bool Hold) const {
460  const Expr *ArgExpr = CE->getArg(Num);
461  SVal ArgVal = state->getSVal(ArgExpr, C.getLocationContext());
462  if (!isa<DefinedOrUnknownSVal>(ArgVal))
463    return 0;
464  DefinedOrUnknownSVal location = cast<DefinedOrUnknownSVal>(ArgVal);
465
466  // Check for null dereferences.
467  if (!isa<Loc>(location))
468    return 0;
469
470  // The explicit NULL case, no operation is performed.
471  ProgramStateRef notNullState, nullState;
472  llvm::tie(notNullState, nullState) = state->assume(location);
473  if (nullState && !notNullState)
474    return 0;
475
476  // Unknown values could easily be okay
477  // Undefined values are handled elsewhere
478  if (ArgVal.isUnknownOrUndef())
479    return 0;
480
481  const MemRegion *R = ArgVal.getAsRegion();
482
483  // Nonlocs can't be freed, of course.
484  // Non-region locations (labels and fixed addresses) also shouldn't be freed.
485  if (!R) {
486    ReportBadFree(C, ArgVal, ArgExpr->getSourceRange());
487    return 0;
488  }
489
490  R = R->StripCasts();
491
492  // Blocks might show up as heap data, but should not be free()d
493  if (isa<BlockDataRegion>(R)) {
494    ReportBadFree(C, ArgVal, ArgExpr->getSourceRange());
495    return 0;
496  }
497
498  const MemSpaceRegion *MS = R->getMemorySpace();
499
500  // Parameters, locals, statics, and globals shouldn't be freed.
501  if (!(isa<UnknownSpaceRegion>(MS) || isa<HeapSpaceRegion>(MS))) {
502    // FIXME: at the time this code was written, malloc() regions were
503    // represented by conjured symbols, which are all in UnknownSpaceRegion.
504    // This means that there isn't actually anything from HeapSpaceRegion
505    // that should be freed, even though we allow it here.
506    // Of course, free() can work on memory allocated outside the current
507    // function, so UnknownSpaceRegion is always a possibility.
508    // False negatives are better than false positives.
509
510    ReportBadFree(C, ArgVal, ArgExpr->getSourceRange());
511    return 0;
512  }
513
514  const SymbolicRegion *SR = dyn_cast<SymbolicRegion>(R);
515  // Various cases could lead to non-symbol values here.
516  // For now, ignore them.
517  if (!SR)
518    return 0;
519
520  SymbolRef Sym = SR->getSymbol();
521  const RefState *RS = state->get<RegionState>(Sym);
522
523  // If the symbol has not been tracked, return. This is possible when free() is
524  // called on a pointer that does not get its pointee directly from malloc().
525  // Full support of this requires inter-procedural analysis.
526  if (!RS)
527    return 0;
528
529  // Check double free.
530  if (RS->isReleased()) {
531    if (ExplodedNode *N = C.generateSink()) {
532      if (!BT_DoubleFree)
533        BT_DoubleFree.reset(
534          new BugType("Double free", "Memory Error"));
535      BugReport *R = new BugReport(*BT_DoubleFree,
536                        "Attempt to free released memory", N);
537      R->addRange(ArgExpr->getSourceRange());
538      R->addVisitor(new MallocBugVisitor(Sym));
539      C.EmitReport(R);
540    }
541    return 0;
542  }
543
544  // Normal free.
545  if (Hold)
546    return state->set<RegionState>(Sym, RefState::getRelinquished(CE));
547  return state->set<RegionState>(Sym, RefState::getReleased(CE));
548}
549
550bool MallocChecker::SummarizeValue(raw_ostream &os, SVal V) {
551  if (nonloc::ConcreteInt *IntVal = dyn_cast<nonloc::ConcreteInt>(&V))
552    os << "an integer (" << IntVal->getValue() << ")";
553  else if (loc::ConcreteInt *ConstAddr = dyn_cast<loc::ConcreteInt>(&V))
554    os << "a constant address (" << ConstAddr->getValue() << ")";
555  else if (loc::GotoLabel *Label = dyn_cast<loc::GotoLabel>(&V))
556    os << "the address of the label '" << Label->getLabel()->getName() << "'";
557  else
558    return false;
559
560  return true;
561}
562
563bool MallocChecker::SummarizeRegion(raw_ostream &os,
564                                    const MemRegion *MR) {
565  switch (MR->getKind()) {
566  case MemRegion::FunctionTextRegionKind: {
567    const FunctionDecl *FD = cast<FunctionTextRegion>(MR)->getDecl();
568    if (FD)
569      os << "the address of the function '" << *FD << '\'';
570    else
571      os << "the address of a function";
572    return true;
573  }
574  case MemRegion::BlockTextRegionKind:
575    os << "block text";
576    return true;
577  case MemRegion::BlockDataRegionKind:
578    // FIXME: where the block came from?
579    os << "a block";
580    return true;
581  default: {
582    const MemSpaceRegion *MS = MR->getMemorySpace();
583
584    if (isa<StackLocalsSpaceRegion>(MS)) {
585      const VarRegion *VR = dyn_cast<VarRegion>(MR);
586      const VarDecl *VD;
587      if (VR)
588        VD = VR->getDecl();
589      else
590        VD = NULL;
591
592      if (VD)
593        os << "the address of the local variable '" << VD->getName() << "'";
594      else
595        os << "the address of a local stack variable";
596      return true;
597    }
598
599    if (isa<StackArgumentsSpaceRegion>(MS)) {
600      const VarRegion *VR = dyn_cast<VarRegion>(MR);
601      const VarDecl *VD;
602      if (VR)
603        VD = VR->getDecl();
604      else
605        VD = NULL;
606
607      if (VD)
608        os << "the address of the parameter '" << VD->getName() << "'";
609      else
610        os << "the address of a parameter";
611      return true;
612    }
613
614    if (isa<GlobalsSpaceRegion>(MS)) {
615      const VarRegion *VR = dyn_cast<VarRegion>(MR);
616      const VarDecl *VD;
617      if (VR)
618        VD = VR->getDecl();
619      else
620        VD = NULL;
621
622      if (VD) {
623        if (VD->isStaticLocal())
624          os << "the address of the static variable '" << VD->getName() << "'";
625        else
626          os << "the address of the global variable '" << VD->getName() << "'";
627      } else
628        os << "the address of a global variable";
629      return true;
630    }
631
632    return false;
633  }
634  }
635}
636
637void MallocChecker::ReportBadFree(CheckerContext &C, SVal ArgVal,
638                                  SourceRange range) const {
639  if (ExplodedNode *N = C.generateSink()) {
640    if (!BT_BadFree)
641      BT_BadFree.reset(new BugType("Bad free", "Memory Error"));
642
643    SmallString<100> buf;
644    llvm::raw_svector_ostream os(buf);
645
646    const MemRegion *MR = ArgVal.getAsRegion();
647    if (MR) {
648      while (const ElementRegion *ER = dyn_cast<ElementRegion>(MR))
649        MR = ER->getSuperRegion();
650
651      // Special case for alloca()
652      if (isa<AllocaRegion>(MR))
653        os << "Argument to free() was allocated by alloca(), not malloc()";
654      else {
655        os << "Argument to free() is ";
656        if (SummarizeRegion(os, MR))
657          os << ", which is not memory allocated by malloc()";
658        else
659          os << "not memory allocated by malloc()";
660      }
661    } else {
662      os << "Argument to free() is ";
663      if (SummarizeValue(os, ArgVal))
664        os << ", which is not memory allocated by malloc()";
665      else
666        os << "not memory allocated by malloc()";
667    }
668
669    BugReport *R = new BugReport(*BT_BadFree, os.str(), N);
670    R->addRange(range);
671    C.EmitReport(R);
672  }
673}
674
675ProgramStateRef MallocChecker::ReallocMem(CheckerContext &C,
676                                          const CallExpr *CE,
677                                          bool FreesOnFail) const {
678  ProgramStateRef state = C.getState();
679  const Expr *arg0Expr = CE->getArg(0);
680  const LocationContext *LCtx = C.getLocationContext();
681  SVal Arg0Val = state->getSVal(arg0Expr, LCtx);
682  if (!isa<DefinedOrUnknownSVal>(Arg0Val))
683    return 0;
684  DefinedOrUnknownSVal arg0Val = cast<DefinedOrUnknownSVal>(Arg0Val);
685
686  SValBuilder &svalBuilder = C.getSValBuilder();
687
688  DefinedOrUnknownSVal PtrEQ =
689    svalBuilder.evalEQ(state, arg0Val, svalBuilder.makeNull());
690
691  // Get the size argument. If there is no size arg then give up.
692  const Expr *Arg1 = CE->getArg(1);
693  if (!Arg1)
694    return 0;
695
696  // Get the value of the size argument.
697  SVal Arg1ValG = state->getSVal(Arg1, LCtx);
698  if (!isa<DefinedOrUnknownSVal>(Arg1ValG))
699    return 0;
700  DefinedOrUnknownSVal Arg1Val = cast<DefinedOrUnknownSVal>(Arg1ValG);
701
702  // Compare the size argument to 0.
703  DefinedOrUnknownSVal SizeZero =
704    svalBuilder.evalEQ(state, Arg1Val,
705                       svalBuilder.makeIntValWithPtrWidth(0, false));
706
707  ProgramStateRef StatePtrIsNull, StatePtrNotNull;
708  llvm::tie(StatePtrIsNull, StatePtrNotNull) = state->assume(PtrEQ);
709  ProgramStateRef StateSizeIsZero, StateSizeNotZero;
710  llvm::tie(StateSizeIsZero, StateSizeNotZero) = state->assume(SizeZero);
711  // We only assume exceptional states if they are definitely true; if the
712  // state is under-constrained, assume regular realloc behavior.
713  bool PrtIsNull = StatePtrIsNull && !StatePtrNotNull;
714  bool SizeIsZero = StateSizeIsZero && !StateSizeNotZero;
715
716  // If the ptr is NULL and the size is not 0, the call is equivalent to
717  // malloc(size).
718  if ( PrtIsNull && !SizeIsZero) {
719    ProgramStateRef stateMalloc = MallocMemAux(C, CE, CE->getArg(1),
720                                               UndefinedVal(), StatePtrIsNull);
721    return stateMalloc;
722  }
723
724  if (PrtIsNull && SizeIsZero)
725    return 0;
726
727  // Get the from and to pointer symbols as in toPtr = realloc(fromPtr, size).
728  assert(!PrtIsNull);
729  SymbolRef FromPtr = arg0Val.getAsSymbol();
730  SVal RetVal = state->getSVal(CE, LCtx);
731  SymbolRef ToPtr = RetVal.getAsSymbol();
732  if (!FromPtr || !ToPtr)
733    return 0;
734
735  // If the size is 0, free the memory.
736  if (SizeIsZero)
737    if (ProgramStateRef stateFree = FreeMemAux(C, CE, StateSizeIsZero,0,false)){
738      // The semantics of the return value are:
739      // If size was equal to 0, either NULL or a pointer suitable to be passed
740      // to free() is returned.
741      stateFree = stateFree->set<ReallocPairs>(ToPtr,
742                                            ReallocPair(FromPtr, FreesOnFail));
743      C.getSymbolManager().addSymbolDependency(ToPtr, FromPtr);
744      return stateFree;
745    }
746
747  // Default behavior.
748  if (ProgramStateRef stateFree = FreeMemAux(C, CE, state, 0, false)) {
749    // FIXME: We should copy the content of the original buffer.
750    ProgramStateRef stateRealloc = MallocMemAux(C, CE, CE->getArg(1),
751                                                UnknownVal(), stateFree);
752    if (!stateRealloc)
753      return 0;
754    stateRealloc = stateRealloc->set<ReallocPairs>(ToPtr,
755                                            ReallocPair(FromPtr, FreesOnFail));
756    C.getSymbolManager().addSymbolDependency(ToPtr, FromPtr);
757    return stateRealloc;
758  }
759  return 0;
760}
761
762ProgramStateRef MallocChecker::CallocMem(CheckerContext &C, const CallExpr *CE){
763  ProgramStateRef state = C.getState();
764  SValBuilder &svalBuilder = C.getSValBuilder();
765  const LocationContext *LCtx = C.getLocationContext();
766  SVal count = state->getSVal(CE->getArg(0), LCtx);
767  SVal elementSize = state->getSVal(CE->getArg(1), LCtx);
768  SVal TotalSize = svalBuilder.evalBinOp(state, BO_Mul, count, elementSize,
769                                        svalBuilder.getContext().getSizeType());
770  SVal zeroVal = svalBuilder.makeZeroVal(svalBuilder.getContext().CharTy);
771
772  return MallocMemAux(C, CE, TotalSize, zeroVal, state);
773}
774
775const Stmt *
776MallocChecker::getAllocationSite(const ExplodedNode *N, SymbolRef Sym,
777                                 CheckerContext &C) const {
778  const LocationContext *LeakContext = N->getLocationContext();
779  // Walk the ExplodedGraph backwards and find the first node that referred to
780  // the tracked symbol.
781  const ExplodedNode *AllocNode = N;
782
783  while (N) {
784    if (!N->getState()->get<RegionState>(Sym))
785      break;
786    // Allocation node, is the last node in the current context in which the
787    // symbol was tracked.
788    if (N->getLocationContext() == LeakContext)
789      AllocNode = N;
790    N = N->pred_empty() ? NULL : *(N->pred_begin());
791  }
792
793  ProgramPoint P = AllocNode->getLocation();
794  if (!isa<StmtPoint>(P))
795    return 0;
796
797  return cast<StmtPoint>(P).getStmt();
798}
799
800void MallocChecker::reportLeak(SymbolRef Sym, ExplodedNode *N,
801                               CheckerContext &C) const {
802  assert(N);
803  if (!BT_Leak) {
804    BT_Leak.reset(new BugType("Memory leak", "Memory Error"));
805    // Leaks should not be reported if they are post-dominated by a sink:
806    // (1) Sinks are higher importance bugs.
807    // (2) NoReturnFunctionChecker uses sink nodes to represent paths ending
808    //     with __noreturn functions such as assert() or exit(). We choose not
809    //     to report leaks on such paths.
810    BT_Leak->setSuppressOnSink(true);
811  }
812
813  // Most bug reports are cached at the location where they occurred.
814  // With leaks, we want to unique them by the location where they were
815  // allocated, and only report a single path.
816  PathDiagnosticLocation LocUsedForUniqueing;
817  if (const Stmt *AllocStmt = getAllocationSite(N, Sym, C))
818    LocUsedForUniqueing = PathDiagnosticLocation::createBegin(AllocStmt,
819                            C.getSourceManager(), N->getLocationContext());
820
821  BugReport *R = new BugReport(*BT_Leak,
822    "Memory is never released; potential memory leak", N, LocUsedForUniqueing);
823  R->addVisitor(new MallocBugVisitor(Sym));
824  C.EmitReport(R);
825}
826
827void MallocChecker::checkDeadSymbols(SymbolReaper &SymReaper,
828                                     CheckerContext &C) const
829{
830  if (!SymReaper.hasDeadSymbols())
831    return;
832
833  ProgramStateRef state = C.getState();
834  RegionStateTy RS = state->get<RegionState>();
835  RegionStateTy::Factory &F = state->get_context<RegionState>();
836
837  bool generateReport = false;
838  llvm::SmallVector<SymbolRef, 2> Errors;
839  for (RegionStateTy::iterator I = RS.begin(), E = RS.end(); I != E; ++I) {
840    if (SymReaper.isDead(I->first)) {
841      if (I->second.isAllocated()) {
842        generateReport = true;
843        Errors.push_back(I->first);
844      }
845      // Remove the dead symbol from the map.
846      RS = F.remove(RS, I->first);
847
848    }
849  }
850
851  // Cleanup the Realloc Pairs Map.
852  ReallocMap RP = state->get<ReallocPairs>();
853  for (ReallocMap::iterator I = RP.begin(), E = RP.end(); I != E; ++I) {
854    if (SymReaper.isDead(I->first) ||
855        SymReaper.isDead(I->second.ReallocatedSym)) {
856      state = state->remove<ReallocPairs>(I->first);
857    }
858  }
859
860  // Generate leak node.
861  static SimpleProgramPointTag Tag("MallocChecker : DeadSymbolsLeak");
862  ExplodedNode *N = C.addTransition(C.getState(), C.getPredecessor(), &Tag);
863
864  if (generateReport) {
865    for (llvm::SmallVector<SymbolRef, 2>::iterator
866         I = Errors.begin(), E = Errors.end(); I != E; ++I) {
867      reportLeak(*I, N, C);
868    }
869  }
870  C.addTransition(state->set<RegionState>(RS), N);
871}
872
873void MallocChecker::checkEndPath(CheckerContext &C) const {
874  ProgramStateRef state = C.getState();
875  RegionStateTy M = state->get<RegionState>();
876
877  // If inside inlined call, skip it.
878  if (C.getLocationContext()->getParent() != 0)
879    return;
880
881  for (RegionStateTy::iterator I = M.begin(), E = M.end(); I != E; ++I) {
882    RefState RS = I->second;
883    if (RS.isAllocated()) {
884      ExplodedNode *N = C.addTransition(state);
885      if (N)
886        reportLeak(I->first, N, C);
887    }
888  }
889}
890
891bool MallocChecker::checkEscape(SymbolRef Sym, const Stmt *S,
892                                CheckerContext &C) const {
893  ProgramStateRef state = C.getState();
894  const RefState *RS = state->get<RegionState>(Sym);
895  if (!RS)
896    return false;
897
898  if (RS->isAllocated()) {
899    state = state->set<RegionState>(Sym, RefState::getEscaped(S));
900    C.addTransition(state);
901    return true;
902  }
903  return false;
904}
905
906void MallocChecker::checkPreStmt(const CallExpr *CE, CheckerContext &C) const {
907  if (isMemFunction(C.getCalleeDecl(CE), C.getASTContext()))
908    return;
909
910  // Check use after free, when a freed pointer is passed to a call.
911  ProgramStateRef State = C.getState();
912  for (CallExpr::const_arg_iterator I = CE->arg_begin(),
913                                    E = CE->arg_end(); I != E; ++I) {
914    const Expr *A = *I;
915    if (A->getType().getTypePtr()->isAnyPointerType()) {
916      SymbolRef Sym = State->getSVal(A, C.getLocationContext()).getAsSymbol();
917      if (!Sym)
918        continue;
919      if (checkUseAfterFree(Sym, C, A))
920        return;
921    }
922  }
923}
924
925void MallocChecker::checkPreStmt(const ReturnStmt *S, CheckerContext &C) const {
926  const Expr *E = S->getRetValue();
927  if (!E)
928    return;
929
930  // Check if we are returning a symbol.
931  SVal RetVal = C.getState()->getSVal(E, C.getLocationContext());
932  SymbolRef Sym = RetVal.getAsSymbol();
933  if (!Sym)
934    // If we are returning a field of the allocated struct or an array element,
935    // the callee could still free the memory.
936    // TODO: This logic should be a part of generic symbol escape callback.
937    if (const MemRegion *MR = RetVal.getAsRegion())
938      if (isa<FieldRegion>(MR) || isa<ElementRegion>(MR))
939        if (const SymbolicRegion *BMR =
940              dyn_cast<SymbolicRegion>(MR->getBaseRegion()))
941          Sym = BMR->getSymbol();
942  if (!Sym)
943    return;
944
945  // Check if we are returning freed memory.
946  if (checkUseAfterFree(Sym, C, E))
947    return;
948
949  // If this function body is not inlined, check if the symbol is escaping.
950  if (C.getLocationContext()->getParent() == 0)
951    checkEscape(Sym, E, C);
952}
953
954bool MallocChecker::checkUseAfterFree(SymbolRef Sym, CheckerContext &C,
955                                      const Stmt *S) const {
956  assert(Sym);
957  const RefState *RS = C.getState()->get<RegionState>(Sym);
958  if (RS && RS->isReleased()) {
959    if (ExplodedNode *N = C.generateSink()) {
960      if (!BT_UseFree)
961        BT_UseFree.reset(new BugType("Use-after-free", "Memory Error"));
962
963      BugReport *R = new BugReport(*BT_UseFree,
964                                   "Use of memory after it is freed",N);
965      if (S)
966        R->addRange(S->getSourceRange());
967      R->addVisitor(new MallocBugVisitor(Sym));
968      C.EmitReport(R);
969      return true;
970    }
971  }
972  return false;
973}
974
975// Check if the location is a freed symbolic region.
976void MallocChecker::checkLocation(SVal l, bool isLoad, const Stmt *S,
977                                  CheckerContext &C) const {
978  SymbolRef Sym = l.getLocSymbolInBase();
979  if (Sym)
980    checkUseAfterFree(Sym, C);
981}
982
983//===----------------------------------------------------------------------===//
984// Check various ways a symbol can be invalidated.
985// TODO: This logic (the next 3 functions) is copied/similar to the
986// RetainRelease checker. We might want to factor this out.
987//===----------------------------------------------------------------------===//
988
989// Stop tracking symbols when a value escapes as a result of checkBind.
990// A value escapes in three possible cases:
991// (1) we are binding to something that is not a memory region.
992// (2) we are binding to a memregion that does not have stack storage
993// (3) we are binding to a memregion with stack storage that the store
994//     does not understand.
995void MallocChecker::checkBind(SVal loc, SVal val, const Stmt *S,
996                              CheckerContext &C) const {
997  // Are we storing to something that causes the value to "escape"?
998  bool escapes = true;
999  ProgramStateRef state = C.getState();
1000
1001  if (loc::MemRegionVal *regionLoc = dyn_cast<loc::MemRegionVal>(&loc)) {
1002    escapes = !regionLoc->getRegion()->hasStackStorage();
1003
1004    if (!escapes) {
1005      // To test (3), generate a new state with the binding added.  If it is
1006      // the same state, then it escapes (since the store cannot represent
1007      // the binding).
1008      escapes = (state == (state->bindLoc(*regionLoc, val)));
1009    }
1010    if (!escapes) {
1011      // Case 4: We do not currently model what happens when a symbol is
1012      // assigned to a struct field, so be conservative here and let the symbol
1013      // go. TODO: This could definitely be improved upon.
1014      escapes = !isa<VarRegion>(regionLoc->getRegion());
1015    }
1016  }
1017
1018  // If our store can represent the binding and we aren't storing to something
1019  // that doesn't have local storage then just return and have the simulation
1020  // state continue as is.
1021  if (!escapes)
1022      return;
1023
1024  // Otherwise, find all symbols referenced by 'val' that we are tracking
1025  // and stop tracking them.
1026  state = state->scanReachableSymbols<StopTrackingCallback>(val).getState();
1027  C.addTransition(state);
1028}
1029
1030// If a symbolic region is assumed to NULL (or another constant), stop tracking
1031// it - assuming that allocation failed on this path.
1032ProgramStateRef MallocChecker::evalAssume(ProgramStateRef state,
1033                                              SVal Cond,
1034                                              bool Assumption) const {
1035  RegionStateTy RS = state->get<RegionState>();
1036  for (RegionStateTy::iterator I = RS.begin(), E = RS.end(); I != E; ++I) {
1037    // If the symbol is assumed to NULL or another constant, this will
1038    // return an APSInt*.
1039    if (state->getSymVal(I.getKey()))
1040      state = state->remove<RegionState>(I.getKey());
1041  }
1042
1043  // Realloc returns 0 when reallocation fails, which means that we should
1044  // restore the state of the pointer being reallocated.
1045  ReallocMap RP = state->get<ReallocPairs>();
1046  for (ReallocMap::iterator I = RP.begin(), E = RP.end(); I != E; ++I) {
1047    // If the symbol is assumed to NULL or another constant, this will
1048    // return an APSInt*.
1049    if (state->getSymVal(I.getKey())) {
1050      SymbolRef ReallocSym = I.getData().ReallocatedSym;
1051      const RefState *RS = state->get<RegionState>(ReallocSym);
1052      if (RS) {
1053        if (RS->isReleased() && ! I.getData().IsFreeOnFailure)
1054          state = state->set<RegionState>(ReallocSym,
1055                             RefState::getAllocateUnchecked(RS->getStmt()));
1056      }
1057      state = state->remove<ReallocPairs>(I.getKey());
1058    }
1059  }
1060
1061  return state;
1062}
1063
1064// Check if the function is known to us. So, for example, we could
1065// conservatively assume it can free/reallocate it's pointer arguments.
1066// (We assume that the pointers cannot escape through calls to system
1067// functions not handled by this checker.)
1068bool MallocChecker::doesNotFreeMemory(const CallOrObjCMessage *Call,
1069                                      ProgramStateRef State) const {
1070  if (!Call)
1071    return false;
1072
1073  // For now, assume that any C++ call can free memory.
1074  // TODO: If we want to be more optimistic here, we'll need to make sure that
1075  // regions escape to C++ containers. They seem to do that even now, but for
1076  // mysterious reasons.
1077  if (Call->isCXXCall())
1078    return false;
1079
1080  const Decl *D = Call->getDecl();
1081  if (!D)
1082    return false;
1083
1084  ASTContext &ASTC = State->getStateManager().getContext();
1085
1086  // If it's one of the allocation functions we can reason about, we model
1087  // it's behavior explicitly.
1088  if (isa<FunctionDecl>(D) && isMemFunction(cast<FunctionDecl>(D), ASTC)) {
1089    return true;
1090  }
1091
1092  // If it's not a system call, assume it frees memory.
1093  SourceManager &SM = ASTC.getSourceManager();
1094  if (!SM.isInSystemHeader(D->getLocation()))
1095    return false;
1096
1097  // Process C/ObjC functions.
1098  if (const FunctionDecl *FD  = dyn_cast_or_null<FunctionDecl>(D)) {
1099    // White list the system functions whose arguments escape.
1100    const IdentifierInfo *II = FD->getIdentifier();
1101    if (!II)
1102      return true;
1103    StringRef FName = II->getName();
1104
1105    // White list thread local storage.
1106    if (FName.equals("pthread_setspecific"))
1107      return false;
1108
1109    // White list the 'XXXNoCopy' ObjC Methods.
1110    if (FName.endswith("NoCopy")) {
1111      // Look for the deallocator argument. We know that the memory ownership
1112      // is not transfered only if the deallocator argument is
1113      // 'kCFAllocatorNull'.
1114      for (unsigned i = 1; i < Call->getNumArgs(); ++i) {
1115        const Expr *ArgE = Call->getArg(i)->IgnoreParenCasts();
1116        if (const DeclRefExpr *DE = dyn_cast<DeclRefExpr>(ArgE)) {
1117          StringRef DeallocatorName = DE->getFoundDecl()->getName();
1118          if (DeallocatorName == "kCFAllocatorNull")
1119            return true;
1120        }
1121      }
1122      return false;
1123    }
1124
1125    // Otherwise, assume that the function does not free memory.
1126    // Most system calls, do not free the memory.
1127    return true;
1128
1129  // Process ObjC functions.
1130  } else if (const ObjCMethodDecl * ObjCD = dyn_cast<ObjCMethodDecl>(D)) {
1131    Selector S = ObjCD->getSelector();
1132
1133    // White list the ObjC functions which do free memory.
1134    // - Anything containing 'freeWhenDone' param set to 1.
1135    //   Ex: dataWithBytesNoCopy:length:freeWhenDone.
1136    for (unsigned i = 1; i < S.getNumArgs(); ++i) {
1137      if (S.getNameForSlot(i).equals("freeWhenDone")) {
1138        if (Call->getArgSVal(i).isConstant(1))
1139          return false;
1140      }
1141    }
1142
1143    // Otherwise, assume that the function does not free memory.
1144    // Most system calls, do not free the memory.
1145    return true;
1146  }
1147
1148  // Otherwise, assume that the function can free memory.
1149  return false;
1150
1151}
1152
1153// If the symbol we are tracking is invalidated, but not explicitly (ex: the &p
1154// escapes, when we are tracking p), do not track the symbol as we cannot reason
1155// about it anymore.
1156ProgramStateRef
1157MallocChecker::checkRegionChanges(ProgramStateRef State,
1158                            const StoreManager::InvalidatedSymbols *invalidated,
1159                                    ArrayRef<const MemRegion *> ExplicitRegions,
1160                                    ArrayRef<const MemRegion *> Regions,
1161                                    const CallOrObjCMessage *Call) const {
1162  if (!invalidated || invalidated->empty())
1163    return State;
1164  llvm::SmallPtrSet<SymbolRef, 8> WhitelistedSymbols;
1165
1166  // If it's a call which might free or reallocate memory, we assume that all
1167  // regions (explicit and implicit) escaped.
1168
1169  // Otherwise, whitelist explicit pointers; we still can track them.
1170  if (!Call || doesNotFreeMemory(Call, State)) {
1171    for (ArrayRef<const MemRegion *>::iterator I = ExplicitRegions.begin(),
1172        E = ExplicitRegions.end(); I != E; ++I) {
1173      if (const SymbolicRegion *R = (*I)->StripCasts()->getAs<SymbolicRegion>())
1174        WhitelistedSymbols.insert(R->getSymbol());
1175    }
1176  }
1177
1178  for (StoreManager::InvalidatedSymbols::const_iterator I=invalidated->begin(),
1179       E = invalidated->end(); I!=E; ++I) {
1180    SymbolRef sym = *I;
1181    if (WhitelistedSymbols.count(sym))
1182      continue;
1183    // The symbol escaped.
1184    if (const RefState *RS = State->get<RegionState>(sym))
1185      State = State->set<RegionState>(sym, RefState::getEscaped(RS->getStmt()));
1186  }
1187  return State;
1188}
1189
1190PathDiagnosticPiece *
1191MallocChecker::MallocBugVisitor::VisitNode(const ExplodedNode *N,
1192                                           const ExplodedNode *PrevN,
1193                                           BugReporterContext &BRC,
1194                                           BugReport &BR) {
1195  const RefState *RS = N->getState()->get<RegionState>(Sym);
1196  const RefState *RSPrev = PrevN->getState()->get<RegionState>(Sym);
1197  if (!RS && !RSPrev)
1198    return 0;
1199
1200  const Stmt *S = 0;
1201  const char *Msg = 0;
1202
1203  // Retrieve the associated statement.
1204  ProgramPoint ProgLoc = N->getLocation();
1205  if (isa<StmtPoint>(ProgLoc))
1206    S = cast<StmtPoint>(ProgLoc).getStmt();
1207  // If an assumption was made on a branch, it should be caught
1208  // here by looking at the state transition.
1209  if (isa<BlockEdge>(ProgLoc)) {
1210    const CFGBlock *srcBlk = cast<BlockEdge>(ProgLoc).getSrc();
1211    S = srcBlk->getTerminator();
1212  }
1213  if (!S)
1214    return 0;
1215
1216  // Find out if this is an interesting point and what is the kind.
1217  if (Mode == Normal) {
1218    if (isAllocated(RS, RSPrev, S))
1219      Msg = "Memory is allocated";
1220    else if (isReleased(RS, RSPrev, S))
1221      Msg = "Memory is released";
1222    else if (isReallocFailedCheck(RS, RSPrev, S)) {
1223      Mode = ReallocationFailed;
1224      Msg = "Reallocation failed";
1225    }
1226
1227  // We are in a special mode if a reallocation failed later in the path.
1228  } else if (Mode == ReallocationFailed) {
1229    // Generate a special diagnostic for the first realloc we find.
1230    if (!isAllocated(RS, RSPrev, S) && !isReleased(RS, RSPrev, S))
1231      return 0;
1232
1233    // Check that the name of the function is realloc.
1234    const CallExpr *CE = dyn_cast<CallExpr>(S);
1235    if (!CE)
1236      return 0;
1237    const FunctionDecl *funDecl = CE->getDirectCallee();
1238    if (!funDecl)
1239      return 0;
1240    StringRef FunName = funDecl->getName();
1241    if (!(FunName.equals("realloc") || FunName.equals("reallocf")))
1242      return 0;
1243    Msg = "Attempt to reallocate memory";
1244    Mode = Normal;
1245  }
1246
1247  if (!Msg)
1248    return 0;
1249
1250  // Generate the extra diagnostic.
1251  PathDiagnosticLocation Pos(S, BRC.getSourceManager(),
1252                             N->getLocationContext());
1253  return new PathDiagnosticEventPiece(Pos, Msg);
1254}
1255
1256
1257#define REGISTER_CHECKER(name) \
1258void ento::register##name(CheckerManager &mgr) {\
1259  registerCStringCheckerBasic(mgr); \
1260  mgr.registerChecker<MallocChecker>()->Filter.C##name = true;\
1261}
1262
1263REGISTER_CHECKER(MallocPessimistic)
1264REGISTER_CHECKER(MallocOptimistic)
1265