MallocChecker.cpp revision b3d7275c1a4a9f676af850cd661b56c4ad7ef5c9 
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 isReleased() const { return K == Released; }
46
47  const Stmt *getStmt() const { return S; }
48
49  bool operator==(const RefState &X) const {
50    return K == X.K && S == X.S;
51  }
52
53  static RefState getAllocateUnchecked(const Stmt *s) {
54    return RefState(AllocateUnchecked, s);
55  }
56  static RefState getAllocateFailed() {
57    return RefState(AllocateFailed, 0);
58  }
59  static RefState getReleased(const Stmt *s) { return RefState(Released, s); }
60  static RefState getEscaped(const Stmt *s) { return RefState(Escaped, s); }
61  static RefState getRelinquished(const Stmt *s) {
62    return RefState(Relinquished, s);
63  }
64
65  void Profile(llvm::FoldingSetNodeID &ID) const {
66    ID.AddInteger(K);
67    ID.AddPointer(S);
68  }
69};
70
71struct ReallocPair {
72  SymbolRef ReallocatedSym;
73  bool IsFreeOnFailure;
74  ReallocPair(SymbolRef S, bool F) : ReallocatedSym(S), IsFreeOnFailure(F) {}
75  void Profile(llvm::FoldingSetNodeID &ID) const {
76    ID.AddInteger(IsFreeOnFailure);
77    ID.AddPointer(ReallocatedSym);
78  }
79  bool operator==(const ReallocPair &X) const {
80    return ReallocatedSym == X.ReallocatedSym &&
81           IsFreeOnFailure == X.IsFreeOnFailure;
82  }
83};
84
85class MallocChecker : public Checker<check::DeadSymbols,
86                                     check::EndPath,
87                                     check::PreStmt<ReturnStmt>,
88                                     check::PreStmt<CallExpr>,
89                                     check::PostStmt<CallExpr>,
90                                     check::Location,
91                                     check::Bind,
92                                     eval::Assume,
93                                     check::RegionChanges>
94{
95  mutable OwningPtr<BugType> BT_DoubleFree;
96  mutable OwningPtr<BugType> BT_Leak;
97  mutable OwningPtr<BugType> BT_UseFree;
98  mutable OwningPtr<BugType> BT_BadFree;
99  mutable IdentifierInfo *II_malloc, *II_free, *II_realloc, *II_calloc,
100                         *II_valloc, *II_reallocf, *II_strndup, *II_strdup;
101
102  static const unsigned InvalidArgIndex = UINT_MAX;
103
104public:
105  MallocChecker() : II_malloc(0), II_free(0), II_realloc(0), II_calloc(0),
106                    II_valloc(0), II_reallocf(0), II_strndup(0), II_strdup(0) {}
107
108  /// In pessimistic mode, the checker assumes that it does not know which
109  /// functions might free the memory.
110  struct ChecksFilter {
111    DefaultBool CMallocPessimistic;
112    DefaultBool CMallocOptimistic;
113  };
114
115  ChecksFilter Filter;
116
117  void checkPreStmt(const CallExpr *S, CheckerContext &C) const;
118  void checkPostStmt(const CallExpr *CE, CheckerContext &C) const;
119  void checkDeadSymbols(SymbolReaper &SymReaper, CheckerContext &C) const;
120  void checkEndPath(CheckerContext &C) const;
121  void checkPreStmt(const ReturnStmt *S, CheckerContext &C) const;
122  ProgramStateRef evalAssume(ProgramStateRef state, SVal Cond,
123                            bool Assumption) const;
124  void checkLocation(SVal l, bool isLoad, const Stmt *S,
125                     CheckerContext &C) const;
126  void checkBind(SVal location, SVal val, const Stmt*S,
127                 CheckerContext &C) const;
128  ProgramStateRef
129  checkRegionChanges(ProgramStateRef state,
130                     const StoreManager::InvalidatedSymbols *invalidated,
131                     ArrayRef<const MemRegion *> ExplicitRegions,
132                     ArrayRef<const MemRegion *> Regions,
133                     const CallOrObjCMessage *Call) const;
134  bool wantsRegionChangeUpdate(ProgramStateRef state) const {
135    return true;
136  }
137
138private:
139  void initIdentifierInfo(ASTContext &C) const;
140
141  /// Check if this is one of the functions which can allocate/reallocate memory
142  /// pointed to by one of its arguments.
143  bool isMemFunction(const FunctionDecl *FD, ASTContext &C) const;
144
145  static ProgramStateRef MallocMemReturnsAttr(CheckerContext &C,
146                                              const CallExpr *CE,
147                                              const OwnershipAttr* Att);
148  static ProgramStateRef MallocMemAux(CheckerContext &C, const CallExpr *CE,
149                                     const Expr *SizeEx, SVal Init,
150                                     ProgramStateRef state) {
151    return MallocMemAux(C, CE,
152                        state->getSVal(SizeEx, C.getLocationContext()),
153                        Init, state);
154  }
155
156  static ProgramStateRef MallocMemAux(CheckerContext &C, const CallExpr *CE,
157                                     SVal SizeEx, SVal Init,
158                                     ProgramStateRef state);
159
160  /// Update the RefState to reflect the new memory allocation.
161  static ProgramStateRef MallocUpdateRefState(CheckerContext &C,
162                                              const CallExpr *CE,
163                                              ProgramStateRef state);
164
165  ProgramStateRef FreeMemAttr(CheckerContext &C, const CallExpr *CE,
166                              const OwnershipAttr* Att) const;
167  ProgramStateRef FreeMemAux(CheckerContext &C, const CallExpr *CE,
168                                 ProgramStateRef state, unsigned Num,
169                                 bool Hold) const;
170
171  ProgramStateRef ReallocMem(CheckerContext &C, const CallExpr *CE,
172                             bool FreesMemOnFailure) const;
173  static ProgramStateRef CallocMem(CheckerContext &C, const CallExpr *CE);
174
175  bool checkEscape(SymbolRef Sym, const Stmt *S, CheckerContext &C) const;
176  bool checkUseAfterFree(SymbolRef Sym, CheckerContext &C,
177                         const Stmt *S = 0) const;
178
179  /// Check if the function is not known to us. So, for example, we could
180  /// conservatively assume it can free/reallocate it's pointer arguments.
181  bool doesNotFreeMemory(const CallOrObjCMessage *Call,
182                         ProgramStateRef State) const;
183
184  static bool SummarizeValue(raw_ostream &os, SVal V);
185  static bool SummarizeRegion(raw_ostream &os, const MemRegion *MR);
186  void ReportBadFree(CheckerContext &C, SVal ArgVal, SourceRange range) const;
187
188  /// Find the location of the allocation for Sym on the path leading to the
189  /// exploded node N.
190  const Stmt *getAllocationSite(const ExplodedNode *N, SymbolRef Sym,
191                                CheckerContext &C) const;
192
193  void reportLeak(SymbolRef Sym, ExplodedNode *N, CheckerContext &C) const;
194
195  /// The bug visitor which allows us to print extra diagnostics along the
196  /// BugReport path. For example, showing the allocation site of the leaked
197  /// region.
198  class MallocBugVisitor : public BugReporterVisitor {
199  protected:
200    enum NotificationMode {
201      Normal,
202      Complete,
203      ReallocationFailed
204    };
205
206    // The allocated region symbol tracked by the main analysis.
207    SymbolRef Sym;
208    NotificationMode Mode;
209
210  public:
211    MallocBugVisitor(SymbolRef S) : Sym(S), Mode(Normal) {}
212    virtual ~MallocBugVisitor() {}
213
214    void Profile(llvm::FoldingSetNodeID &ID) const {
215      static int X = 0;
216      ID.AddPointer(&X);
217      ID.AddPointer(Sym);
218    }
219
220    inline bool isAllocated(const RefState *S, const RefState *SPrev,
221                            const Stmt *Stmt) {
222      // Did not track -> allocated. Other state (released) -> allocated.
223      return (Stmt && isa<CallExpr>(Stmt) &&
224              (S && S->isAllocated()) && (!SPrev || !SPrev->isAllocated()));
225    }
226
227    inline bool isReleased(const RefState *S, const RefState *SPrev,
228                           const Stmt *Stmt) {
229      // Did not track -> released. Other state (allocated) -> released.
230      return (Stmt && isa<CallExpr>(Stmt) &&
231              (S && S->isReleased()) && (!SPrev || !SPrev->isReleased()));
232    }
233
234    inline bool isReallocFailedCheck(const RefState *S, const RefState *SPrev,
235                                     const Stmt *Stmt) {
236      // If the expression is not a call, and the state change is
237      // released -> allocated, it must be the realloc return value
238      // check. If we have to handle more cases here, it might be cleaner just
239      // to track this extra bit in the state itself.
240      return ((!Stmt || !isa<CallExpr>(Stmt)) &&
241              (S && S->isAllocated()) && (SPrev && !SPrev->isAllocated()));
242    }
243
244    PathDiagnosticPiece *VisitNode(const ExplodedNode *N,
245                                   const ExplodedNode *PrevN,
246                                   BugReporterContext &BRC,
247                                   BugReport &BR);
248  };
249};
250} // end anonymous namespace
251
252typedef llvm::ImmutableMap<SymbolRef, RefState> RegionStateTy;
253typedef llvm::ImmutableMap<SymbolRef, ReallocPair > ReallocMap;
254class RegionState {};
255class ReallocPairs {};
256namespace clang {
257namespace ento {
258  template <>
259  struct ProgramStateTrait<RegionState>
260    : public ProgramStatePartialTrait<RegionStateTy> {
261    static void *GDMIndex() { static int x; return &x; }
262  };
263
264  template <>
265  struct ProgramStateTrait<ReallocPairs>
266    : public ProgramStatePartialTrait<ReallocMap> {
267    static void *GDMIndex() { static int x; return &x; }
268  };
269}
270}
271
272namespace {
273class StopTrackingCallback : public SymbolVisitor {
274  ProgramStateRef state;
275public:
276  StopTrackingCallback(ProgramStateRef st) : state(st) {}
277  ProgramStateRef getState() const { return state; }
278
279  bool VisitSymbol(SymbolRef sym) {
280    state = state->remove<RegionState>(sym);
281    return true;
282  }
283};
284} // end anonymous namespace
285
286void MallocChecker::initIdentifierInfo(ASTContext &Ctx) const {
287  if (!II_malloc)
288    II_malloc = &Ctx.Idents.get("malloc");
289  if (!II_free)
290    II_free = &Ctx.Idents.get("free");
291  if (!II_realloc)
292    II_realloc = &Ctx.Idents.get("realloc");
293  if (!II_reallocf)
294    II_reallocf = &Ctx.Idents.get("reallocf");
295  if (!II_calloc)
296    II_calloc = &Ctx.Idents.get("calloc");
297  if (!II_valloc)
298    II_valloc = &Ctx.Idents.get("valloc");
299  if (!II_strdup)
300    II_strdup = &Ctx.Idents.get("strdup");
301  if (!II_strndup)
302    II_strndup = &Ctx.Idents.get("strndup");
303}
304
305bool MallocChecker::isMemFunction(const FunctionDecl *FD, ASTContext &C) const {
306  if (!FD)
307    return false;
308  IdentifierInfo *FunI = FD->getIdentifier();
309  if (!FunI)
310    return false;
311
312  initIdentifierInfo(C);
313
314  if (FunI == II_malloc || FunI == II_free || FunI == II_realloc ||
315      FunI == II_reallocf || FunI == II_calloc || FunI == II_valloc ||
316      FunI == II_strdup || FunI == II_strndup)
317    return true;
318
319  if (Filter.CMallocOptimistic && FD->hasAttrs() &&
320      FD->specific_attr_begin<OwnershipAttr>() !=
321          FD->specific_attr_end<OwnershipAttr>())
322    return true;
323
324
325  return false;
326}
327
328void MallocChecker::checkPostStmt(const CallExpr *CE, CheckerContext &C) const {
329  const FunctionDecl *FD = C.getCalleeDecl(CE);
330  if (!FD)
331    return;
332
333  initIdentifierInfo(C.getASTContext());
334  IdentifierInfo *FunI = FD->getIdentifier();
335  if (!FunI)
336    return;
337
338  ProgramStateRef State = C.getState();
339  if (FunI == II_malloc || FunI == II_valloc) {
340    State = MallocMemAux(C, CE, CE->getArg(0), UndefinedVal(), State);
341  } else if (FunI == II_realloc) {
342    State = ReallocMem(C, CE, false);
343  } else if (FunI == II_reallocf) {
344    State = ReallocMem(C, CE, true);
345  } else if (FunI == II_calloc) {
346    State = CallocMem(C, CE);
347  } else if (FunI == II_free) {
348    State = FreeMemAux(C, CE, C.getState(), 0, false);
349  } else if (FunI == II_strdup) {
350    State = MallocUpdateRefState(C, CE, State);
351  } else if (FunI == II_strndup) {
352    State = MallocUpdateRefState(C, CE, State);
353  } else if (Filter.CMallocOptimistic) {
354    // Check all the attributes, if there are any.
355    // There can be multiple of these attributes.
356    if (FD->hasAttrs())
357      for (specific_attr_iterator<OwnershipAttr>
358          i = FD->specific_attr_begin<OwnershipAttr>(),
359          e = FD->specific_attr_end<OwnershipAttr>();
360          i != e; ++i) {
361        switch ((*i)->getOwnKind()) {
362        case OwnershipAttr::Returns:
363          State = MallocMemReturnsAttr(C, CE, *i);
364          break;
365        case OwnershipAttr::Takes:
366        case OwnershipAttr::Holds:
367          State = FreeMemAttr(C, CE, *i);
368          break;
369        }
370      }
371  }
372  C.addTransition(State);
373}
374
375ProgramStateRef MallocChecker::MallocMemReturnsAttr(CheckerContext &C,
376                                                    const CallExpr *CE,
377                                                    const OwnershipAttr* Att) {
378  if (Att->getModule() != "malloc")
379    return 0;
380
381  OwnershipAttr::args_iterator I = Att->args_begin(), E = Att->args_end();
382  if (I != E) {
383    return MallocMemAux(C, CE, CE->getArg(*I), UndefinedVal(), C.getState());
384  }
385  return MallocMemAux(C, CE, UnknownVal(), UndefinedVal(), C.getState());
386}
387
388ProgramStateRef MallocChecker::MallocMemAux(CheckerContext &C,
389                                           const CallExpr *CE,
390                                           SVal Size, SVal Init,
391                                           ProgramStateRef state) {
392  // Get the return value.
393  SVal retVal = state->getSVal(CE, C.getLocationContext());
394
395  // We expect the malloc functions to return a pointer.
396  if (!isa<Loc>(retVal))
397    return 0;
398
399  // Fill the region with the initialization value.
400  state = state->bindDefault(retVal, Init);
401
402  // Set the region's extent equal to the Size parameter.
403  const SymbolicRegion *R =
404      dyn_cast_or_null<SymbolicRegion>(retVal.getAsRegion());
405  if (!R)
406    return 0;
407  if (isa<DefinedOrUnknownSVal>(Size)) {
408    SValBuilder &svalBuilder = C.getSValBuilder();
409    DefinedOrUnknownSVal Extent = R->getExtent(svalBuilder);
410    DefinedOrUnknownSVal DefinedSize = cast<DefinedOrUnknownSVal>(Size);
411    DefinedOrUnknownSVal extentMatchesSize =
412        svalBuilder.evalEQ(state, Extent, DefinedSize);
413
414    state = state->assume(extentMatchesSize, true);
415    assert(state);
416  }
417
418  return MallocUpdateRefState(C, CE, state);
419}
420
421ProgramStateRef MallocChecker::MallocUpdateRefState(CheckerContext &C,
422                                                    const CallExpr *CE,
423                                                    ProgramStateRef state) {
424  // Get the return value.
425  SVal retVal = state->getSVal(CE, C.getLocationContext());
426
427  // We expect the malloc functions to return a pointer.
428  if (!isa<Loc>(retVal))
429    return 0;
430
431  SymbolRef Sym = retVal.getAsLocSymbol();
432  assert(Sym);
433
434  // Set the symbol's state to Allocated.
435  return state->set<RegionState>(Sym, RefState::getAllocateUnchecked(CE));
436
437}
438
439ProgramStateRef MallocChecker::FreeMemAttr(CheckerContext &C,
440                                           const CallExpr *CE,
441                                           const OwnershipAttr* Att) const {
442  if (Att->getModule() != "malloc")
443    return 0;
444
445  ProgramStateRef State = C.getState();
446
447  for (OwnershipAttr::args_iterator I = Att->args_begin(), E = Att->args_end();
448       I != E; ++I) {
449    ProgramStateRef StateI = FreeMemAux(C, CE, State, *I,
450                               Att->getOwnKind() == OwnershipAttr::Holds);
451    if (StateI)
452      State = StateI;
453  }
454  return State;
455}
456
457ProgramStateRef MallocChecker::FreeMemAux(CheckerContext &C,
458                                          const CallExpr *CE,
459                                          ProgramStateRef state,
460                                          unsigned Num,
461                                          bool Hold) const {
462  const Expr *ArgExpr = CE->getArg(Num);
463  SVal ArgVal = state->getSVal(ArgExpr, C.getLocationContext());
464  if (!isa<DefinedOrUnknownSVal>(ArgVal))
465    return 0;
466  DefinedOrUnknownSVal location = cast<DefinedOrUnknownSVal>(ArgVal);
467
468  // Check for null dereferences.
469  if (!isa<Loc>(location))
470    return 0;
471
472  // The explicit NULL case, no operation is performed.
473  ProgramStateRef notNullState, nullState;
474  llvm::tie(notNullState, nullState) = state->assume(location);
475  if (nullState && !notNullState)
476    return 0;
477
478  // Unknown values could easily be okay
479  // Undefined values are handled elsewhere
480  if (ArgVal.isUnknownOrUndef())
481    return 0;
482
483  const MemRegion *R = ArgVal.getAsRegion();
484
485  // Nonlocs can't be freed, of course.
486  // Non-region locations (labels and fixed addresses) also shouldn't be freed.
487  if (!R) {
488    ReportBadFree(C, ArgVal, ArgExpr->getSourceRange());
489    return 0;
490  }
491
492  R = R->StripCasts();
493
494  // Blocks might show up as heap data, but should not be free()d
495  if (isa<BlockDataRegion>(R)) {
496    ReportBadFree(C, ArgVal, ArgExpr->getSourceRange());
497    return 0;
498  }
499
500  const MemSpaceRegion *MS = R->getMemorySpace();
501
502  // Parameters, locals, statics, and globals shouldn't be freed.
503  if (!(isa<UnknownSpaceRegion>(MS) || isa<HeapSpaceRegion>(MS))) {
504    // FIXME: at the time this code was written, malloc() regions were
505    // represented by conjured symbols, which are all in UnknownSpaceRegion.
506    // This means that there isn't actually anything from HeapSpaceRegion
507    // that should be freed, even though we allow it here.
508    // Of course, free() can work on memory allocated outside the current
509    // function, so UnknownSpaceRegion is always a possibility.
510    // False negatives are better than false positives.
511
512    ReportBadFree(C, ArgVal, ArgExpr->getSourceRange());
513    return 0;
514  }
515
516  const SymbolicRegion *SR = dyn_cast<SymbolicRegion>(R);
517  // Various cases could lead to non-symbol values here.
518  // For now, ignore them.
519  if (!SR)
520    return 0;
521
522  SymbolRef Sym = SR->getSymbol();
523  const RefState *RS = state->get<RegionState>(Sym);
524
525  // If the symbol has not been tracked, return. This is possible when free() is
526  // called on a pointer that does not get its pointee directly from malloc().
527  // Full support of this requires inter-procedural analysis.
528  if (!RS)
529    return 0;
530
531  // Check double free.
532  if (RS->isReleased()) {
533    if (ExplodedNode *N = C.generateSink()) {
534      if (!BT_DoubleFree)
535        BT_DoubleFree.reset(
536          new BugType("Double free", "Memory Error"));
537      BugReport *R = new BugReport(*BT_DoubleFree,
538                        "Attempt to free released memory", N);
539      R->addRange(ArgExpr->getSourceRange());
540      R->addVisitor(new MallocBugVisitor(Sym));
541      C.EmitReport(R);
542    }
543    return 0;
544  }
545
546  // Normal free.
547  if (Hold)
548    return state->set<RegionState>(Sym, RefState::getRelinquished(CE));
549  return state->set<RegionState>(Sym, RefState::getReleased(CE));
550}
551
552bool MallocChecker::SummarizeValue(raw_ostream &os, SVal V) {
553  if (nonloc::ConcreteInt *IntVal = dyn_cast<nonloc::ConcreteInt>(&V))
554    os << "an integer (" << IntVal->getValue() << ")";
555  else if (loc::ConcreteInt *ConstAddr = dyn_cast<loc::ConcreteInt>(&V))
556    os << "a constant address (" << ConstAddr->getValue() << ")";
557  else if (loc::GotoLabel *Label = dyn_cast<loc::GotoLabel>(&V))
558    os << "the address of the label '" << Label->getLabel()->getName() << "'";
559  else
560    return false;
561
562  return true;
563}
564
565bool MallocChecker::SummarizeRegion(raw_ostream &os,
566                                    const MemRegion *MR) {
567  switch (MR->getKind()) {
568  case MemRegion::FunctionTextRegionKind: {
569    const FunctionDecl *FD = cast<FunctionTextRegion>(MR)->getDecl();
570    if (FD)
571      os << "the address of the function '" << *FD << '\'';
572    else
573      os << "the address of a function";
574    return true;
575  }
576  case MemRegion::BlockTextRegionKind:
577    os << "block text";
578    return true;
579  case MemRegion::BlockDataRegionKind:
580    // FIXME: where the block came from?
581    os << "a block";
582    return true;
583  default: {
584    const MemSpaceRegion *MS = MR->getMemorySpace();
585
586    if (isa<StackLocalsSpaceRegion>(MS)) {
587      const VarRegion *VR = dyn_cast<VarRegion>(MR);
588      const VarDecl *VD;
589      if (VR)
590        VD = VR->getDecl();
591      else
592        VD = NULL;
593
594      if (VD)
595        os << "the address of the local variable '" << VD->getName() << "'";
596      else
597        os << "the address of a local stack variable";
598      return true;
599    }
600
601    if (isa<StackArgumentsSpaceRegion>(MS)) {
602      const VarRegion *VR = dyn_cast<VarRegion>(MR);
603      const VarDecl *VD;
604      if (VR)
605        VD = VR->getDecl();
606      else
607        VD = NULL;
608
609      if (VD)
610        os << "the address of the parameter '" << VD->getName() << "'";
611      else
612        os << "the address of a parameter";
613      return true;
614    }
615
616    if (isa<GlobalsSpaceRegion>(MS)) {
617      const VarRegion *VR = dyn_cast<VarRegion>(MR);
618      const VarDecl *VD;
619      if (VR)
620        VD = VR->getDecl();
621      else
622        VD = NULL;
623
624      if (VD) {
625        if (VD->isStaticLocal())
626          os << "the address of the static variable '" << VD->getName() << "'";
627        else
628          os << "the address of the global variable '" << VD->getName() << "'";
629      } else
630        os << "the address of a global variable";
631      return true;
632    }
633
634    return false;
635  }
636  }
637}
638
639void MallocChecker::ReportBadFree(CheckerContext &C, SVal ArgVal,
640                                  SourceRange range) const {
641  if (ExplodedNode *N = C.generateSink()) {
642    if (!BT_BadFree)
643      BT_BadFree.reset(new BugType("Bad free", "Memory Error"));
644
645    SmallString<100> buf;
646    llvm::raw_svector_ostream os(buf);
647
648    const MemRegion *MR = ArgVal.getAsRegion();
649    if (MR) {
650      while (const ElementRegion *ER = dyn_cast<ElementRegion>(MR))
651        MR = ER->getSuperRegion();
652
653      // Special case for alloca()
654      if (isa<AllocaRegion>(MR))
655        os << "Argument to free() was allocated by alloca(), not malloc()";
656      else {
657        os << "Argument to free() is ";
658        if (SummarizeRegion(os, MR))
659          os << ", which is not memory allocated by malloc()";
660        else
661          os << "not memory allocated by malloc()";
662      }
663    } else {
664      os << "Argument to free() is ";
665      if (SummarizeValue(os, ArgVal))
666        os << ", which is not memory allocated by malloc()";
667      else
668        os << "not memory allocated by malloc()";
669    }
670
671    BugReport *R = new BugReport(*BT_BadFree, os.str(), N);
672    R->addRange(range);
673    C.EmitReport(R);
674  }
675}
676
677ProgramStateRef MallocChecker::ReallocMem(CheckerContext &C,
678                                          const CallExpr *CE,
679                                          bool FreesOnFail) const {
680  ProgramStateRef state = C.getState();
681  const Expr *arg0Expr = CE->getArg(0);
682  const LocationContext *LCtx = C.getLocationContext();
683  SVal Arg0Val = state->getSVal(arg0Expr, LCtx);
684  if (!isa<DefinedOrUnknownSVal>(Arg0Val))
685    return 0;
686  DefinedOrUnknownSVal arg0Val = cast<DefinedOrUnknownSVal>(Arg0Val);
687
688  SValBuilder &svalBuilder = C.getSValBuilder();
689
690  DefinedOrUnknownSVal PtrEQ =
691    svalBuilder.evalEQ(state, arg0Val, svalBuilder.makeNull());
692
693  // Get the size argument. If there is no size arg then give up.
694  const Expr *Arg1 = CE->getArg(1);
695  if (!Arg1)
696    return 0;
697
698  // Get the value of the size argument.
699  SVal Arg1ValG = state->getSVal(Arg1, LCtx);
700  if (!isa<DefinedOrUnknownSVal>(Arg1ValG))
701    return 0;
702  DefinedOrUnknownSVal Arg1Val = cast<DefinedOrUnknownSVal>(Arg1ValG);
703
704  // Compare the size argument to 0.
705  DefinedOrUnknownSVal SizeZero =
706    svalBuilder.evalEQ(state, Arg1Val,
707                       svalBuilder.makeIntValWithPtrWidth(0, false));
708
709  ProgramStateRef StatePtrIsNull, StatePtrNotNull;
710  llvm::tie(StatePtrIsNull, StatePtrNotNull) = state->assume(PtrEQ);
711  ProgramStateRef StateSizeIsZero, StateSizeNotZero;
712  llvm::tie(StateSizeIsZero, StateSizeNotZero) = state->assume(SizeZero);
713  // We only assume exceptional states if they are definitely true; if the
714  // state is under-constrained, assume regular realloc behavior.
715  bool PrtIsNull = StatePtrIsNull && !StatePtrNotNull;
716  bool SizeIsZero = StateSizeIsZero && !StateSizeNotZero;
717
718  // If the ptr is NULL and the size is not 0, the call is equivalent to
719  // malloc(size).
720  if ( PrtIsNull && !SizeIsZero) {
721    ProgramStateRef stateMalloc = MallocMemAux(C, CE, CE->getArg(1),
722                                               UndefinedVal(), StatePtrIsNull);
723    return stateMalloc;
724  }
725
726  if (PrtIsNull && SizeIsZero)
727    return 0;
728
729  // Get the from and to pointer symbols as in toPtr = realloc(fromPtr, size).
730  assert(!PrtIsNull);
731  SymbolRef FromPtr = arg0Val.getAsSymbol();
732  SVal RetVal = state->getSVal(CE, LCtx);
733  SymbolRef ToPtr = RetVal.getAsSymbol();
734  if (!FromPtr || !ToPtr)
735    return 0;
736
737  // If the size is 0, free the memory.
738  if (SizeIsZero)
739    if (ProgramStateRef stateFree = FreeMemAux(C, CE, StateSizeIsZero,0,false)){
740      // The semantics of the return value are:
741      // If size was equal to 0, either NULL or a pointer suitable to be passed
742      // to free() is returned.
743      stateFree = stateFree->set<ReallocPairs>(ToPtr,
744                                            ReallocPair(FromPtr, FreesOnFail));
745      C.getSymbolManager().addSymbolDependency(ToPtr, FromPtr);
746      return stateFree;
747    }
748
749  // Default behavior.
750  if (ProgramStateRef stateFree = FreeMemAux(C, CE, state, 0, false)) {
751    // FIXME: We should copy the content of the original buffer.
752    ProgramStateRef stateRealloc = MallocMemAux(C, CE, CE->getArg(1),
753                                                UnknownVal(), stateFree);
754    if (!stateRealloc)
755      return 0;
756    stateRealloc = stateRealloc->set<ReallocPairs>(ToPtr,
757                                            ReallocPair(FromPtr, FreesOnFail));
758    C.getSymbolManager().addSymbolDependency(ToPtr, FromPtr);
759    return stateRealloc;
760  }
761  return 0;
762}
763
764ProgramStateRef MallocChecker::CallocMem(CheckerContext &C, const CallExpr *CE){
765  ProgramStateRef state = C.getState();
766  SValBuilder &svalBuilder = C.getSValBuilder();
767  const LocationContext *LCtx = C.getLocationContext();
768  SVal count = state->getSVal(CE->getArg(0), LCtx);
769  SVal elementSize = state->getSVal(CE->getArg(1), LCtx);
770  SVal TotalSize = svalBuilder.evalBinOp(state, BO_Mul, count, elementSize,
771                                        svalBuilder.getContext().getSizeType());
772  SVal zeroVal = svalBuilder.makeZeroVal(svalBuilder.getContext().CharTy);
773
774  return MallocMemAux(C, CE, TotalSize, zeroVal, state);
775}
776
777const Stmt *
778MallocChecker::getAllocationSite(const ExplodedNode *N, SymbolRef Sym,
779                                 CheckerContext &C) const {
780  const LocationContext *LeakContext = N->getLocationContext();
781  // Walk the ExplodedGraph backwards and find the first node that referred to
782  // the tracked symbol.
783  const ExplodedNode *AllocNode = N;
784
785  while (N) {
786    if (!N->getState()->get<RegionState>(Sym))
787      break;
788    // Allocation node, is the last node in the current context in which the
789    // symbol was tracked.
790    if (N->getLocationContext() == LeakContext)
791      AllocNode = N;
792    N = N->pred_empty() ? NULL : *(N->pred_begin());
793  }
794
795  ProgramPoint P = AllocNode->getLocation();
796  if (!isa<StmtPoint>(P))
797    return 0;
798
799  return cast<StmtPoint>(P).getStmt();
800}
801
802void MallocChecker::reportLeak(SymbolRef Sym, ExplodedNode *N,
803                               CheckerContext &C) const {
804  assert(N);
805  if (!BT_Leak) {
806    BT_Leak.reset(new BugType("Memory leak", "Memory Error"));
807    // Leaks should not be reported if they are post-dominated by a sink:
808    // (1) Sinks are higher importance bugs.
809    // (2) NoReturnFunctionChecker uses sink nodes to represent paths ending
810    //     with __noreturn functions such as assert() or exit(). We choose not
811    //     to report leaks on such paths.
812    BT_Leak->setSuppressOnSink(true);
813  }
814
815  // Most bug reports are cached at the location where they occurred.
816  // With leaks, we want to unique them by the location where they were
817  // allocated, and only report a single path.
818  PathDiagnosticLocation LocUsedForUniqueing;
819  if (const Stmt *AllocStmt = getAllocationSite(N, Sym, C))
820    LocUsedForUniqueing = PathDiagnosticLocation::createBegin(AllocStmt,
821                            C.getSourceManager(), N->getLocationContext());
822
823  BugReport *R = new BugReport(*BT_Leak,
824    "Memory is never released; potential memory leak", N, LocUsedForUniqueing);
825  R->addVisitor(new MallocBugVisitor(Sym));
826  C.EmitReport(R);
827}
828
829void MallocChecker::checkDeadSymbols(SymbolReaper &SymReaper,
830                                     CheckerContext &C) const
831{
832  if (!SymReaper.hasDeadSymbols())
833    return;
834
835  ProgramStateRef state = C.getState();
836  RegionStateTy RS = state->get<RegionState>();
837  RegionStateTy::Factory &F = state->get_context<RegionState>();
838
839  bool generateReport = false;
840  llvm::SmallVector<SymbolRef, 2> Errors;
841  for (RegionStateTy::iterator I = RS.begin(), E = RS.end(); I != E; ++I) {
842    if (SymReaper.isDead(I->first)) {
843      if (I->second.isAllocated()) {
844        generateReport = true;
845        Errors.push_back(I->first);
846      }
847      // Remove the dead symbol from the map.
848      RS = F.remove(RS, I->first);
849
850    }
851  }
852
853  // Cleanup the Realloc Pairs Map.
854  ReallocMap RP = state->get<ReallocPairs>();
855  for (ReallocMap::iterator I = RP.begin(), E = RP.end(); I != E; ++I) {
856    if (SymReaper.isDead(I->first) ||
857        SymReaper.isDead(I->second.ReallocatedSym)) {
858      state = state->remove<ReallocPairs>(I->first);
859    }
860  }
861
862  // Generate leak node.
863  static SimpleProgramPointTag Tag("MallocChecker : DeadSymbolsLeak");
864  ExplodedNode *N = C.addTransition(C.getState(), C.getPredecessor(), &Tag);
865
866  if (generateReport) {
867    for (llvm::SmallVector<SymbolRef, 2>::iterator
868         I = Errors.begin(), E = Errors.end(); I != E; ++I) {
869      reportLeak(*I, N, C);
870    }
871  }
872  C.addTransition(state->set<RegionState>(RS), N);
873}
874
875void MallocChecker::checkEndPath(CheckerContext &C) const {
876  ProgramStateRef state = C.getState();
877  RegionStateTy M = state->get<RegionState>();
878
879  // If inside inlined call, skip it.
880  if (C.getLocationContext()->getParent() != 0)
881    return;
882
883  for (RegionStateTy::iterator I = M.begin(), E = M.end(); I != E; ++I) {
884    RefState RS = I->second;
885    if (RS.isAllocated()) {
886      ExplodedNode *N = C.addTransition(state);
887      if (N)
888        reportLeak(I->first, N, C);
889    }
890  }
891}
892
893bool MallocChecker::checkEscape(SymbolRef Sym, const Stmt *S,
894                                CheckerContext &C) const {
895  ProgramStateRef state = C.getState();
896  const RefState *RS = state->get<RegionState>(Sym);
897  if (!RS)
898    return false;
899
900  if (RS->isAllocated()) {
901    state = state->set<RegionState>(Sym, RefState::getEscaped(S));
902    C.addTransition(state);
903    return true;
904  }
905  return false;
906}
907
908void MallocChecker::checkPreStmt(const CallExpr *CE, CheckerContext &C) const {
909  if (isMemFunction(C.getCalleeDecl(CE), C.getASTContext()))
910    return;
911
912  // Check use after free, when a freed pointer is passed to a call.
913  ProgramStateRef State = C.getState();
914  for (CallExpr::const_arg_iterator I = CE->arg_begin(),
915                                    E = CE->arg_end(); I != E; ++I) {
916    const Expr *A = *I;
917    if (A->getType().getTypePtr()->isAnyPointerType()) {
918      SymbolRef Sym = State->getSVal(A, C.getLocationContext()).getAsSymbol();
919      if (!Sym)
920        continue;
921      if (checkUseAfterFree(Sym, C, A))
922        return;
923    }
924  }
925}
926
927void MallocChecker::checkPreStmt(const ReturnStmt *S, CheckerContext &C) const {
928  const Expr *E = S->getRetValue();
929  if (!E)
930    return;
931
932  // Check if we are returning a symbol.
933  SVal RetVal = C.getState()->getSVal(E, C.getLocationContext());
934  SymbolRef Sym = RetVal.getAsSymbol();
935  if (!Sym)
936    // If we are returning a field of the allocated struct or an array element,
937    // the callee could still free the memory.
938    // TODO: This logic should be a part of generic symbol escape callback.
939    if (const MemRegion *MR = RetVal.getAsRegion())
940      if (isa<FieldRegion>(MR) || isa<ElementRegion>(MR))
941        if (const SymbolicRegion *BMR =
942              dyn_cast<SymbolicRegion>(MR->getBaseRegion()))
943          Sym = BMR->getSymbol();
944  if (!Sym)
945    return;
946
947  // Check if we are returning freed memory.
948  if (checkUseAfterFree(Sym, C, E))
949    return;
950
951  // If this function body is not inlined, check if the symbol is escaping.
952  if (C.getLocationContext()->getParent() == 0)
953    checkEscape(Sym, E, C);
954}
955
956bool MallocChecker::checkUseAfterFree(SymbolRef Sym, CheckerContext &C,
957                                      const Stmt *S) const {
958  assert(Sym);
959  const RefState *RS = C.getState()->get<RegionState>(Sym);
960  if (RS && RS->isReleased()) {
961    if (ExplodedNode *N = C.generateSink()) {
962      if (!BT_UseFree)
963        BT_UseFree.reset(new BugType("Use-after-free", "Memory Error"));
964
965      BugReport *R = new BugReport(*BT_UseFree,
966                                   "Use of memory after it is freed",N);
967      if (S)
968        R->addRange(S->getSourceRange());
969      R->addVisitor(new MallocBugVisitor(Sym));
970      C.EmitReport(R);
971      return true;
972    }
973  }
974  return false;
975}
976
977// Check if the location is a freed symbolic region.
978void MallocChecker::checkLocation(SVal l, bool isLoad, const Stmt *S,
979                                  CheckerContext &C) const {
980  SymbolRef Sym = l.getLocSymbolInBase();
981  if (Sym)
982    checkUseAfterFree(Sym, C);
983}
984
985//===----------------------------------------------------------------------===//
986// Check various ways a symbol can be invalidated.
987// TODO: This logic (the next 3 functions) is copied/similar to the
988// RetainRelease checker. We might want to factor this out.
989//===----------------------------------------------------------------------===//
990
991// Stop tracking symbols when a value escapes as a result of checkBind.
992// A value escapes in three possible cases:
993// (1) we are binding to something that is not a memory region.
994// (2) we are binding to a memregion that does not have stack storage
995// (3) we are binding to a memregion with stack storage that the store
996//     does not understand.
997void MallocChecker::checkBind(SVal loc, SVal val, const Stmt *S,
998                              CheckerContext &C) const {
999  // Are we storing to something that causes the value to "escape"?
1000  bool escapes = true;
1001  ProgramStateRef state = C.getState();
1002
1003  if (loc::MemRegionVal *regionLoc = dyn_cast<loc::MemRegionVal>(&loc)) {
1004    escapes = !regionLoc->getRegion()->hasStackStorage();
1005
1006    if (!escapes) {
1007      // To test (3), generate a new state with the binding added.  If it is
1008      // the same state, then it escapes (since the store cannot represent
1009      // the binding).
1010      escapes = (state == (state->bindLoc(*regionLoc, val)));
1011    }
1012    if (!escapes) {
1013      // Case 4: We do not currently model what happens when a symbol is
1014      // assigned to a struct field, so be conservative here and let the symbol
1015      // go. TODO: This could definitely be improved upon.
1016      escapes = !isa<VarRegion>(regionLoc->getRegion());
1017    }
1018  }
1019
1020  // If our store can represent the binding and we aren't storing to something
1021  // that doesn't have local storage then just return and have the simulation
1022  // state continue as is.
1023  if (!escapes)
1024      return;
1025
1026  // Otherwise, find all symbols referenced by 'val' that we are tracking
1027  // and stop tracking them.
1028  state = state->scanReachableSymbols<StopTrackingCallback>(val).getState();
1029  C.addTransition(state);
1030}
1031
1032// If a symbolic region is assumed to NULL (or another constant), stop tracking
1033// it - assuming that allocation failed on this path.
1034ProgramStateRef MallocChecker::evalAssume(ProgramStateRef state,
1035                                              SVal Cond,
1036                                              bool Assumption) const {
1037  RegionStateTy RS = state->get<RegionState>();
1038  for (RegionStateTy::iterator I = RS.begin(), E = RS.end(); I != E; ++I) {
1039    // If the symbol is assumed to NULL or another constant, this will
1040    // return an APSInt*.
1041    if (state->getSymVal(I.getKey()))
1042      state = state->remove<RegionState>(I.getKey());
1043  }
1044
1045  // Realloc returns 0 when reallocation fails, which means that we should
1046  // restore the state of the pointer being reallocated.
1047  ReallocMap RP = state->get<ReallocPairs>();
1048  for (ReallocMap::iterator I = RP.begin(), E = RP.end(); I != E; ++I) {
1049    // If the symbol is assumed to NULL or another constant, this will
1050    // return an APSInt*.
1051    if (state->getSymVal(I.getKey())) {
1052      SymbolRef ReallocSym = I.getData().ReallocatedSym;
1053      const RefState *RS = state->get<RegionState>(ReallocSym);
1054      if (RS) {
1055        if (RS->isReleased() && ! I.getData().IsFreeOnFailure)
1056          state = state->set<RegionState>(ReallocSym,
1057                             RefState::getAllocateUnchecked(RS->getStmt()));
1058      }
1059      state = state->remove<ReallocPairs>(I.getKey());
1060    }
1061  }
1062
1063  return state;
1064}
1065
1066// Check if the function is known to us. So, for example, we could
1067// conservatively assume it can free/reallocate it's pointer arguments.
1068// (We assume that the pointers cannot escape through calls to system
1069// functions not handled by this checker.)
1070bool MallocChecker::doesNotFreeMemory(const CallOrObjCMessage *Call,
1071                                      ProgramStateRef State) const {
1072  if (!Call)
1073    return false;
1074
1075  // For now, assume that any C++ call can free memory.
1076  // TODO: If we want to be more optimistic here, we'll need to make sure that
1077  // regions escape to C++ containers. They seem to do that even now, but for
1078  // mysterious reasons.
1079  if (Call->isCXXCall())
1080    return false;
1081
1082  const Decl *D = Call->getDecl();
1083  if (!D)
1084    return false;
1085
1086  ASTContext &ASTC = State->getStateManager().getContext();
1087
1088  // If it's one of the allocation functions we can reason about, we model
1089  // it's behavior explicitly.
1090  if (isa<FunctionDecl>(D) && isMemFunction(cast<FunctionDecl>(D), ASTC)) {
1091    return true;
1092  }
1093
1094  // If it's not a system call, assume it frees memory.
1095  SourceManager &SM = ASTC.getSourceManager();
1096  if (!SM.isInSystemHeader(D->getLocation()))
1097    return false;
1098
1099  // Process C/ObjC functions.
1100  if (const FunctionDecl *FD  = dyn_cast_or_null<FunctionDecl>(D)) {
1101    // White list the system functions whose arguments escape.
1102    const IdentifierInfo *II = FD->getIdentifier();
1103    if (!II)
1104      return true;
1105    StringRef FName = II->getName();
1106
1107    // White list thread local storage.
1108    if (FName.equals("pthread_setspecific"))
1109      return false;
1110
1111    // White list the 'XXXNoCopy' ObjC Methods.
1112    if (FName.endswith("NoCopy")) {
1113      // Look for the deallocator argument. We know that the memory ownership
1114      // is not transfered only if the deallocator argument is
1115      // 'kCFAllocatorNull'.
1116      for (unsigned i = 1; i < Call->getNumArgs(); ++i) {
1117        const Expr *ArgE = Call->getArg(i)->IgnoreParenCasts();
1118        if (const DeclRefExpr *DE = dyn_cast<DeclRefExpr>(ArgE)) {
1119          StringRef DeallocatorName = DE->getFoundDecl()->getName();
1120          if (DeallocatorName == "kCFAllocatorNull")
1121            return true;
1122        }
1123      }
1124      return false;
1125    }
1126
1127    // PR12101
1128    // Many CoreFoundation and CoreGraphics might allow a tracked object
1129    // to escape.
1130    if (Call->isCFCGAllowingEscape(FName))
1131      return false;
1132
1133    // Associating streams with malloced buffers. The pointer can escape if
1134    // 'closefn' is specified (and if that function does free memory).
1135    // Currently, we do not inspect the 'closefn' function (PR12101).
1136    if (FName == "funopen")
1137      if (Call->getNumArgs() >= 4 && !Call->getArgSVal(4).isConstant(0))
1138        return false;
1139
1140    // Do not warn on pointers passed to 'setbuf' when used with std streams,
1141    // these leaks might be intentional when setting the buffer for stdio.
1142    // http://stackoverflow.com/questions/2671151/who-frees-setvbuf-buffer
1143    if (FName == "setbuf" || FName =="setbuffer" ||
1144        FName == "setlinebuf" || FName == "setvbuf") {
1145      if (Call->getNumArgs() >= 1)
1146        if (const DeclRefExpr *Arg =
1147              dyn_cast<DeclRefExpr>(Call->getArg(0)->IgnoreParenCasts()))
1148          if (const VarDecl *D = dyn_cast<VarDecl>(Arg->getDecl()))
1149              if (D->getCanonicalDecl()->getName().find("std")
1150                                                   != StringRef::npos)
1151                return false;
1152    }
1153
1154    // A bunch of other functions, which take ownership of a pointer (See retain
1155    // release checker). Not all the parameters here are invalidated, but the
1156    // Malloc checker cannot differentiate between them. The right way of doing
1157    // this would be to implement a pointer escapes callback.
1158    if (FName == "CVPixelBufferCreateWithBytes" ||
1159        FName == "CGBitmapContextCreateWithData" ||
1160        FName == "CVPixelBufferCreateWithPlanarBytes") {
1161      return false;
1162    }
1163
1164    // Otherwise, assume that the function does not free memory.
1165    // Most system calls, do not free the memory.
1166    return true;
1167
1168  // Process ObjC functions.
1169  } else if (const ObjCMethodDecl * ObjCD = dyn_cast<ObjCMethodDecl>(D)) {
1170    Selector S = ObjCD->getSelector();
1171
1172    // White list the ObjC functions which do free memory.
1173    // - Anything containing 'freeWhenDone' param set to 1.
1174    //   Ex: dataWithBytesNoCopy:length:freeWhenDone.
1175    for (unsigned i = 1; i < S.getNumArgs(); ++i) {
1176      if (S.getNameForSlot(i).equals("freeWhenDone")) {
1177        if (Call->getArgSVal(i).isConstant(1))
1178          return false;
1179      }
1180    }
1181
1182    // Otherwise, assume that the function does not free memory.
1183    // Most system calls, do not free the memory.
1184    return true;
1185  }
1186
1187  // Otherwise, assume that the function can free memory.
1188  return false;
1189
1190}
1191
1192// If the symbol we are tracking is invalidated, but not explicitly (ex: the &p
1193// escapes, when we are tracking p), do not track the symbol as we cannot reason
1194// about it anymore.
1195ProgramStateRef
1196MallocChecker::checkRegionChanges(ProgramStateRef State,
1197                            const StoreManager::InvalidatedSymbols *invalidated,
1198                                    ArrayRef<const MemRegion *> ExplicitRegions,
1199                                    ArrayRef<const MemRegion *> Regions,
1200                                    const CallOrObjCMessage *Call) const {
1201  if (!invalidated || invalidated->empty())
1202    return State;
1203  llvm::SmallPtrSet<SymbolRef, 8> WhitelistedSymbols;
1204
1205  // If it's a call which might free or reallocate memory, we assume that all
1206  // regions (explicit and implicit) escaped.
1207
1208  // Otherwise, whitelist explicit pointers; we still can track them.
1209  if (!Call || doesNotFreeMemory(Call, State)) {
1210    for (ArrayRef<const MemRegion *>::iterator I = ExplicitRegions.begin(),
1211        E = ExplicitRegions.end(); I != E; ++I) {
1212      if (const SymbolicRegion *R = (*I)->StripCasts()->getAs<SymbolicRegion>())
1213        WhitelistedSymbols.insert(R->getSymbol());
1214    }
1215  }
1216
1217  for (StoreManager::InvalidatedSymbols::const_iterator I=invalidated->begin(),
1218       E = invalidated->end(); I!=E; ++I) {
1219    SymbolRef sym = *I;
1220    if (WhitelistedSymbols.count(sym))
1221      continue;
1222    // The symbol escaped.
1223    if (const RefState *RS = State->get<RegionState>(sym))
1224      State = State->set<RegionState>(sym, RefState::getEscaped(RS->getStmt()));
1225  }
1226  return State;
1227}
1228
1229PathDiagnosticPiece *
1230MallocChecker::MallocBugVisitor::VisitNode(const ExplodedNode *N,
1231                                           const ExplodedNode *PrevN,
1232                                           BugReporterContext &BRC,
1233                                           BugReport &BR) {
1234  const RefState *RS = N->getState()->get<RegionState>(Sym);
1235  const RefState *RSPrev = PrevN->getState()->get<RegionState>(Sym);
1236  if (!RS && !RSPrev)
1237    return 0;
1238
1239  const Stmt *S = 0;
1240  const char *Msg = 0;
1241
1242  // Retrieve the associated statement.
1243  ProgramPoint ProgLoc = N->getLocation();
1244  if (isa<StmtPoint>(ProgLoc))
1245    S = cast<StmtPoint>(ProgLoc).getStmt();
1246  // If an assumption was made on a branch, it should be caught
1247  // here by looking at the state transition.
1248  if (isa<BlockEdge>(ProgLoc)) {
1249    const CFGBlock *srcBlk = cast<BlockEdge>(ProgLoc).getSrc();
1250    S = srcBlk->getTerminator();
1251  }
1252  if (!S)
1253    return 0;
1254
1255  // Find out if this is an interesting point and what is the kind.
1256  if (Mode == Normal) {
1257    if (isAllocated(RS, RSPrev, S))
1258      Msg = "Memory is allocated";
1259    else if (isReleased(RS, RSPrev, S))
1260      Msg = "Memory is released";
1261    else if (isReallocFailedCheck(RS, RSPrev, S)) {
1262      Mode = ReallocationFailed;
1263      Msg = "Reallocation failed";
1264    }
1265
1266  // We are in a special mode if a reallocation failed later in the path.
1267  } else if (Mode == ReallocationFailed) {
1268    // Generate a special diagnostic for the first realloc we find.
1269    if (!isAllocated(RS, RSPrev, S) && !isReleased(RS, RSPrev, S))
1270      return 0;
1271
1272    // Check that the name of the function is realloc.
1273    const CallExpr *CE = dyn_cast<CallExpr>(S);
1274    if (!CE)
1275      return 0;
1276    const FunctionDecl *funDecl = CE->getDirectCallee();
1277    if (!funDecl)
1278      return 0;
1279    StringRef FunName = funDecl->getName();
1280    if (!(FunName.equals("realloc") || FunName.equals("reallocf")))
1281      return 0;
1282    Msg = "Attempt to reallocate memory";
1283    Mode = Normal;
1284  }
1285
1286  if (!Msg)
1287    return 0;
1288
1289  // Generate the extra diagnostic.
1290  PathDiagnosticLocation Pos(S, BRC.getSourceManager(),
1291                             N->getLocationContext());
1292  return new PathDiagnosticEventPiece(Pos, Msg);
1293}
1294
1295
1296#define REGISTER_CHECKER(name) \
1297void ento::register##name(CheckerManager &mgr) {\
1298  registerCStringCheckerBasic(mgr); \
1299  mgr.registerChecker<MallocChecker>()->Filter.C##name = true;\
1300}
1301
1302REGISTER_CHECKER(MallocPessimistic)
1303REGISTER_CHECKER(MallocOptimistic)
1304