forked from OSchip/llvm-project
				
			
		
			
				
	
	
		
			739 lines
		
	
	
		
			25 KiB
		
	
	
	
		
			C++
		
	
	
	
			
		
		
	
	
			739 lines
		
	
	
		
			25 KiB
		
	
	
	
		
			C++
		
	
	
	
//=== MallocChecker.cpp - A malloc/free checker -------------------*- C++ -*--//
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//
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//                     The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file defines malloc/free checker, which checks for potential memory
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// leaks, double free, and use-after-free problems.
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//
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//===----------------------------------------------------------------------===//
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#include "ClangSACheckers.h"
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#include "clang/StaticAnalyzer/Core/Checker.h"
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#include "clang/StaticAnalyzer/Core/CheckerManager.h"
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#include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
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#include "clang/StaticAnalyzer/Core/BugReporter/BugType.h"
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#include "clang/StaticAnalyzer/Core/PathSensitive/GRState.h"
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#include "clang/StaticAnalyzer/Core/PathSensitive/GRStateTrait.h"
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#include "clang/StaticAnalyzer/Core/PathSensitive/SymbolManager.h"
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#include "llvm/ADT/ImmutableMap.h"
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using namespace clang;
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using namespace ento;
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namespace {
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class RefState {
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  enum Kind { AllocateUnchecked, AllocateFailed, Released, Escaped,
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              Relinquished } K;
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  const Stmt *S;
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public:
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  RefState(Kind k, const Stmt *s) : K(k), S(s) {}
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  bool isAllocated() const { return K == AllocateUnchecked; }
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  //bool isFailed() const { return K == AllocateFailed; }
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  bool isReleased() const { return K == Released; }
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  //bool isEscaped() const { return K == Escaped; }
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  //bool isRelinquished() const { return K == Relinquished; }
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  bool operator==(const RefState &X) const {
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    return K == X.K && S == X.S;
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  }
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  static RefState getAllocateUnchecked(const Stmt *s) { 
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    return RefState(AllocateUnchecked, s); 
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  }
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  static RefState getAllocateFailed() {
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    return RefState(AllocateFailed, 0);
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  }
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  static RefState getReleased(const Stmt *s) { return RefState(Released, s); }
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  static RefState getEscaped(const Stmt *s) { return RefState(Escaped, s); }
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  static RefState getRelinquished(const Stmt *s) {
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    return RefState(Relinquished, s);
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  }
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  void Profile(llvm::FoldingSetNodeID &ID) const {
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    ID.AddInteger(K);
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    ID.AddPointer(S);
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  }
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};
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class RegionState {};
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class MallocChecker : public Checker<eval::Call, check::DeadSymbols, check::EndPath, check::PreStmt<ReturnStmt>, check::Location,
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                               check::Bind, eval::Assume> {
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  mutable llvm::OwningPtr<BuiltinBug> BT_DoubleFree;
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  mutable llvm::OwningPtr<BuiltinBug> BT_Leak;
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  mutable llvm::OwningPtr<BuiltinBug> BT_UseFree;
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  mutable llvm::OwningPtr<BuiltinBug> BT_UseRelinquished;
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  mutable llvm::OwningPtr<BuiltinBug> BT_BadFree;
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  mutable IdentifierInfo *II_malloc, *II_free, *II_realloc, *II_calloc;
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public:
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  MallocChecker() : II_malloc(0), II_free(0), II_realloc(0), II_calloc(0) {}
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  bool evalCall(const CallExpr *CE, CheckerContext &C) const;
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  void checkDeadSymbols(SymbolReaper &SymReaper, CheckerContext &C) const;
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  void checkEndPath(EndOfFunctionNodeBuilder &B, ExprEngine &Eng) const;
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  void checkPreStmt(const ReturnStmt *S, CheckerContext &C) const;
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  const GRState *evalAssume(const GRState *state, SVal Cond,
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                            bool Assumption) const;
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  void checkLocation(SVal l, bool isLoad, CheckerContext &C) const;
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  void checkBind(SVal location, SVal val, CheckerContext &C) const;
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private:
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  static void MallocMem(CheckerContext &C, const CallExpr *CE);
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  static void MallocMemReturnsAttr(CheckerContext &C, const CallExpr *CE,
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                                   const OwnershipAttr* Att);
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  static const GRState *MallocMemAux(CheckerContext &C, const CallExpr *CE,
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                                     const Expr *SizeEx, SVal Init,
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                                     const GRState *state) {
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    return MallocMemAux(C, CE, state->getSVal(SizeEx), Init, state);
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  }
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  static const GRState *MallocMemAux(CheckerContext &C, const CallExpr *CE,
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                                     SVal SizeEx, SVal Init,
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                                     const GRState *state);
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  void FreeMem(CheckerContext &C, const CallExpr *CE) const;
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  void FreeMemAttr(CheckerContext &C, const CallExpr *CE,
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                   const OwnershipAttr* Att) const;
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  const GRState *FreeMemAux(CheckerContext &C, const CallExpr *CE,
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                           const GRState *state, unsigned Num, bool Hold) const;
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  void ReallocMem(CheckerContext &C, const CallExpr *CE) const;
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  static void CallocMem(CheckerContext &C, const CallExpr *CE);
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  static bool SummarizeValue(llvm::raw_ostream& os, SVal V);
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  static bool SummarizeRegion(llvm::raw_ostream& os, const MemRegion *MR);
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  void ReportBadFree(CheckerContext &C, SVal ArgVal, SourceRange range) const;
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};
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} // end anonymous namespace
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typedef llvm::ImmutableMap<SymbolRef, RefState> RegionStateTy;
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namespace clang {
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namespace ento {
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  template <>
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  struct GRStateTrait<RegionState> 
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    : public GRStatePartialTrait<RegionStateTy> {
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    static void *GDMIndex() { static int x; return &x; }
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  };
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}
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}
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bool MallocChecker::evalCall(const CallExpr *CE, CheckerContext &C) const {
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  const GRState *state = C.getState();
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  const Expr *Callee = CE->getCallee();
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  SVal L = state->getSVal(Callee);
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  const FunctionDecl *FD = L.getAsFunctionDecl();
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  if (!FD)
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    return false;
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  ASTContext &Ctx = C.getASTContext();
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  if (!II_malloc)
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    II_malloc = &Ctx.Idents.get("malloc");
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  if (!II_free)
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    II_free = &Ctx.Idents.get("free");
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  if (!II_realloc)
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    II_realloc = &Ctx.Idents.get("realloc");
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  if (!II_calloc)
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    II_calloc = &Ctx.Idents.get("calloc");
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  if (FD->getIdentifier() == II_malloc) {
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    MallocMem(C, CE);
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    return true;
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  }
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  if (FD->getIdentifier() == II_free) {
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    FreeMem(C, CE);
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    return true;
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  }
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  if (FD->getIdentifier() == II_realloc) {
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    ReallocMem(C, CE);
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    return true;
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  }
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  if (FD->getIdentifier() == II_calloc) {
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    CallocMem(C, CE);
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    return true;
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  }
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  // Check all the attributes, if there are any.
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  // There can be multiple of these attributes.
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  bool rv = false;
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  if (FD->hasAttrs()) {
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    for (specific_attr_iterator<OwnershipAttr>
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                  i = FD->specific_attr_begin<OwnershipAttr>(),
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                  e = FD->specific_attr_end<OwnershipAttr>();
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         i != e; ++i) {
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      switch ((*i)->getOwnKind()) {
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      case OwnershipAttr::Returns: {
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        MallocMemReturnsAttr(C, CE, *i);
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        rv = true;
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        break;
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      }
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      case OwnershipAttr::Takes:
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      case OwnershipAttr::Holds: {
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        FreeMemAttr(C, CE, *i);
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        rv = true;
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        break;
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      }
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      default:
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        break;
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      }
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    }
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  }
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  return rv;
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}
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void MallocChecker::MallocMem(CheckerContext &C, const CallExpr *CE) {
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  const GRState *state = MallocMemAux(C, CE, CE->getArg(0), UndefinedVal(),
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                                      C.getState());
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  C.addTransition(state);
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}
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void MallocChecker::MallocMemReturnsAttr(CheckerContext &C, const CallExpr *CE,
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                                         const OwnershipAttr* Att) {
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  if (Att->getModule() != "malloc")
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    return;
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  OwnershipAttr::args_iterator I = Att->args_begin(), E = Att->args_end();
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  if (I != E) {
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    const GRState *state =
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        MallocMemAux(C, CE, CE->getArg(*I), UndefinedVal(), C.getState());
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    C.addTransition(state);
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    return;
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  }
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  const GRState *state = MallocMemAux(C, CE, UnknownVal(), UndefinedVal(),
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                                        C.getState());
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  C.addTransition(state);
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}
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const GRState *MallocChecker::MallocMemAux(CheckerContext &C,  
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                                           const CallExpr *CE,
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                                           SVal Size, SVal Init,
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                                           const GRState *state) {
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  unsigned Count = C.getNodeBuilder().getCurrentBlockCount();
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  SValBuilder &svalBuilder = C.getSValBuilder();
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  // Set the return value.
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  SVal retVal = svalBuilder.getConjuredSymbolVal(NULL, CE, CE->getType(), Count);
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  state = state->BindExpr(CE, retVal);
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  // Fill the region with the initialization value.
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  state = state->bindDefault(retVal, Init);
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  // Set the region's extent equal to the Size parameter.
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  const SymbolicRegion *R = cast<SymbolicRegion>(retVal.getAsRegion());
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  DefinedOrUnknownSVal Extent = R->getExtent(svalBuilder);
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  DefinedOrUnknownSVal DefinedSize = cast<DefinedOrUnknownSVal>(Size);
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  DefinedOrUnknownSVal extentMatchesSize =
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    svalBuilder.evalEQ(state, Extent, DefinedSize);
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  state = state->assume(extentMatchesSize, true);
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  assert(state);
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  SymbolRef Sym = retVal.getAsLocSymbol();
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  assert(Sym);
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  // Set the symbol's state to Allocated.
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  return state->set<RegionState>(Sym, RefState::getAllocateUnchecked(CE));
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}
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void MallocChecker::FreeMem(CheckerContext &C, const CallExpr *CE) const {
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  const GRState *state = FreeMemAux(C, CE, C.getState(), 0, false);
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  if (state)
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    C.addTransition(state);
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}
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void MallocChecker::FreeMemAttr(CheckerContext &C, const CallExpr *CE,
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                                const OwnershipAttr* Att) const {
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  if (Att->getModule() != "malloc")
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    return;
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  for (OwnershipAttr::args_iterator I = Att->args_begin(), E = Att->args_end();
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       I != E; ++I) {
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    const GRState *state = FreeMemAux(C, CE, C.getState(), *I,
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                                      Att->getOwnKind() == OwnershipAttr::Holds);
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    if (state)
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      C.addTransition(state);
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  }
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}
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const GRState *MallocChecker::FreeMemAux(CheckerContext &C, const CallExpr *CE,
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                                         const GRState *state, unsigned Num,
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                                         bool Hold) const {
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  const Expr *ArgExpr = CE->getArg(Num);
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  SVal ArgVal = state->getSVal(ArgExpr);
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  DefinedOrUnknownSVal location = cast<DefinedOrUnknownSVal>(ArgVal);
 | 
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 | 
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  // Check for null dereferences.
 | 
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  if (!isa<Loc>(location))
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    return state;
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 | 
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  // FIXME: Technically using 'Assume' here can result in a path
 | 
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  //  bifurcation.  In such cases we need to return two states, not just one.
 | 
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  const GRState *notNullState, *nullState;
 | 
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  llvm::tie(notNullState, nullState) = state->assume(location);
 | 
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 | 
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  // The explicit NULL case, no operation is performed.
 | 
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  if (nullState && !notNullState)
 | 
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    return nullState;
 | 
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 | 
						|
  assert(notNullState);
 | 
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 | 
						|
  // Unknown values could easily be okay
 | 
						|
  // Undefined values are handled elsewhere
 | 
						|
  if (ArgVal.isUnknownOrUndef())
 | 
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    return notNullState;
 | 
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 | 
						|
  const MemRegion *R = ArgVal.getAsRegion();
 | 
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 | 
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  // Nonlocs can't be freed, of course.
 | 
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  // Non-region locations (labels and fixed addresses) also shouldn't be freed.
 | 
						|
  if (!R) {
 | 
						|
    ReportBadFree(C, ArgVal, ArgExpr->getSourceRange());
 | 
						|
    return NULL;
 | 
						|
  }
 | 
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 | 
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  R = R->StripCasts();
 | 
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 | 
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  // Blocks might show up as heap data, but should not be free()d
 | 
						|
  if (isa<BlockDataRegion>(R)) {
 | 
						|
    ReportBadFree(C, ArgVal, ArgExpr->getSourceRange());
 | 
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    return NULL;
 | 
						|
  }
 | 
						|
  
 | 
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  const MemSpaceRegion *MS = R->getMemorySpace();
 | 
						|
  
 | 
						|
  // Parameters, locals, statics, and globals shouldn't be freed.
 | 
						|
  if (!(isa<UnknownSpaceRegion>(MS) || isa<HeapSpaceRegion>(MS))) {
 | 
						|
    // FIXME: at the time this code was written, malloc() regions were
 | 
						|
    // represented by conjured symbols, which are all in UnknownSpaceRegion.
 | 
						|
    // This means that there isn't actually anything from HeapSpaceRegion
 | 
						|
    // that should be freed, even though we allow it here.
 | 
						|
    // Of course, free() can work on memory allocated outside the current
 | 
						|
    // function, so UnknownSpaceRegion is always a possibility.
 | 
						|
    // False negatives are better than false positives.
 | 
						|
    
 | 
						|
    ReportBadFree(C, ArgVal, ArgExpr->getSourceRange());
 | 
						|
    return NULL;
 | 
						|
  }
 | 
						|
  
 | 
						|
  const SymbolicRegion *SR = dyn_cast<SymbolicRegion>(R);
 | 
						|
  // Various cases could lead to non-symbol values here.
 | 
						|
  // For now, ignore them.
 | 
						|
  if (!SR)
 | 
						|
    return notNullState;
 | 
						|
 | 
						|
  SymbolRef Sym = SR->getSymbol();
 | 
						|
  const RefState *RS = state->get<RegionState>(Sym);
 | 
						|
 | 
						|
  // If the symbol has not been tracked, return. This is possible when free() is
 | 
						|
  // called on a pointer that does not get its pointee directly from malloc(). 
 | 
						|
  // Full support of this requires inter-procedural analysis.
 | 
						|
  if (!RS)
 | 
						|
    return notNullState;
 | 
						|
 | 
						|
  // Check double free.
 | 
						|
  if (RS->isReleased()) {
 | 
						|
    if (ExplodedNode *N = C.generateSink()) {
 | 
						|
      if (!BT_DoubleFree)
 | 
						|
        BT_DoubleFree.reset(
 | 
						|
          new BuiltinBug("Double free",
 | 
						|
                         "Try to free a memory block that has been released"));
 | 
						|
      // FIXME: should find where it's freed last time.
 | 
						|
      BugReport *R = new BugReport(*BT_DoubleFree, 
 | 
						|
                                   BT_DoubleFree->getDescription(), N);
 | 
						|
      C.EmitReport(R);
 | 
						|
    }
 | 
						|
    return NULL;
 | 
						|
  }
 | 
						|
 | 
						|
  // Normal free.
 | 
						|
  if (Hold)
 | 
						|
    return notNullState->set<RegionState>(Sym, RefState::getRelinquished(CE));
 | 
						|
  return notNullState->set<RegionState>(Sym, RefState::getReleased(CE));
 | 
						|
}
 | 
						|
 | 
						|
bool MallocChecker::SummarizeValue(llvm::raw_ostream& os, SVal V) {
 | 
						|
  if (nonloc::ConcreteInt *IntVal = dyn_cast<nonloc::ConcreteInt>(&V))
 | 
						|
    os << "an integer (" << IntVal->getValue() << ")";
 | 
						|
  else if (loc::ConcreteInt *ConstAddr = dyn_cast<loc::ConcreteInt>(&V))
 | 
						|
    os << "a constant address (" << ConstAddr->getValue() << ")";
 | 
						|
  else if (loc::GotoLabel *Label = dyn_cast<loc::GotoLabel>(&V))
 | 
						|
    os << "the address of the label '" << Label->getLabel()->getName() << "'";
 | 
						|
  else
 | 
						|
    return false;
 | 
						|
  
 | 
						|
  return true;
 | 
						|
}
 | 
						|
 | 
						|
bool MallocChecker::SummarizeRegion(llvm::raw_ostream& os,
 | 
						|
                                    const MemRegion *MR) {
 | 
						|
  switch (MR->getKind()) {
 | 
						|
  case MemRegion::FunctionTextRegionKind: {
 | 
						|
    const FunctionDecl *FD = cast<FunctionTextRegion>(MR)->getDecl();
 | 
						|
    if (FD)
 | 
						|
      os << "the address of the function '" << FD << "'";
 | 
						|
    else
 | 
						|
      os << "the address of a function";
 | 
						|
    return true;
 | 
						|
  }
 | 
						|
  case MemRegion::BlockTextRegionKind:
 | 
						|
    os << "block text";
 | 
						|
    return true;
 | 
						|
  case MemRegion::BlockDataRegionKind:
 | 
						|
    // FIXME: where the block came from?
 | 
						|
    os << "a block";
 | 
						|
    return true;
 | 
						|
  default: {
 | 
						|
    const MemSpaceRegion *MS = MR->getMemorySpace();
 | 
						|
    
 | 
						|
    switch (MS->getKind()) {
 | 
						|
    case MemRegion::StackLocalsSpaceRegionKind: {
 | 
						|
      const VarRegion *VR = dyn_cast<VarRegion>(MR);
 | 
						|
      const VarDecl *VD;
 | 
						|
      if (VR)
 | 
						|
        VD = VR->getDecl();
 | 
						|
      else
 | 
						|
        VD = NULL;
 | 
						|
      
 | 
						|
      if (VD)
 | 
						|
        os << "the address of the local variable '" << VD->getName() << "'";
 | 
						|
      else
 | 
						|
        os << "the address of a local stack variable";
 | 
						|
      return true;
 | 
						|
    }
 | 
						|
    case MemRegion::StackArgumentsSpaceRegionKind: {
 | 
						|
      const VarRegion *VR = dyn_cast<VarRegion>(MR);
 | 
						|
      const VarDecl *VD;
 | 
						|
      if (VR)
 | 
						|
        VD = VR->getDecl();
 | 
						|
      else
 | 
						|
        VD = NULL;
 | 
						|
      
 | 
						|
      if (VD)
 | 
						|
        os << "the address of the parameter '" << VD->getName() << "'";
 | 
						|
      else
 | 
						|
        os << "the address of a parameter";
 | 
						|
      return true;
 | 
						|
    }
 | 
						|
    case MemRegion::NonStaticGlobalSpaceRegionKind:
 | 
						|
    case MemRegion::StaticGlobalSpaceRegionKind: {
 | 
						|
      const VarRegion *VR = dyn_cast<VarRegion>(MR);
 | 
						|
      const VarDecl *VD;
 | 
						|
      if (VR)
 | 
						|
        VD = VR->getDecl();
 | 
						|
      else
 | 
						|
        VD = NULL;
 | 
						|
      
 | 
						|
      if (VD) {
 | 
						|
        if (VD->isStaticLocal())
 | 
						|
          os << "the address of the static variable '" << VD->getName() << "'";
 | 
						|
        else
 | 
						|
          os << "the address of the global variable '" << VD->getName() << "'";
 | 
						|
      } else
 | 
						|
        os << "the address of a global variable";
 | 
						|
      return true;
 | 
						|
    }
 | 
						|
    default:
 | 
						|
      return false;
 | 
						|
    }
 | 
						|
  }
 | 
						|
  }
 | 
						|
}
 | 
						|
 | 
						|
void MallocChecker::ReportBadFree(CheckerContext &C, SVal ArgVal,
 | 
						|
                                  SourceRange range) const {
 | 
						|
  if (ExplodedNode *N = C.generateSink()) {
 | 
						|
    if (!BT_BadFree)
 | 
						|
      BT_BadFree.reset(new BuiltinBug("Bad free"));
 | 
						|
    
 | 
						|
    llvm::SmallString<100> buf;
 | 
						|
    llvm::raw_svector_ostream os(buf);
 | 
						|
    
 | 
						|
    const MemRegion *MR = ArgVal.getAsRegion();
 | 
						|
    if (MR) {
 | 
						|
      while (const ElementRegion *ER = dyn_cast<ElementRegion>(MR))
 | 
						|
        MR = ER->getSuperRegion();
 | 
						|
      
 | 
						|
      // Special case for alloca()
 | 
						|
      if (isa<AllocaRegion>(MR))
 | 
						|
        os << "Argument to free() was allocated by alloca(), not malloc()";
 | 
						|
      else {
 | 
						|
        os << "Argument to free() is ";
 | 
						|
        if (SummarizeRegion(os, MR))
 | 
						|
          os << ", which is not memory allocated by malloc()";
 | 
						|
        else
 | 
						|
          os << "not memory allocated by malloc()";
 | 
						|
      }
 | 
						|
    } else {
 | 
						|
      os << "Argument to free() is ";
 | 
						|
      if (SummarizeValue(os, ArgVal))
 | 
						|
        os << ", which is not memory allocated by malloc()";
 | 
						|
      else
 | 
						|
        os << "not memory allocated by malloc()";
 | 
						|
    }
 | 
						|
    
 | 
						|
    EnhancedBugReport *R = new EnhancedBugReport(*BT_BadFree, os.str(), N);
 | 
						|
    R->addRange(range);
 | 
						|
    C.EmitReport(R);
 | 
						|
  }
 | 
						|
}
 | 
						|
 | 
						|
void MallocChecker::ReallocMem(CheckerContext &C, const CallExpr *CE) const {
 | 
						|
  const GRState *state = C.getState();
 | 
						|
  const Expr *arg0Expr = CE->getArg(0);
 | 
						|
  DefinedOrUnknownSVal arg0Val 
 | 
						|
    = cast<DefinedOrUnknownSVal>(state->getSVal(arg0Expr));
 | 
						|
 | 
						|
  SValBuilder &svalBuilder = C.getSValBuilder();
 | 
						|
 | 
						|
  DefinedOrUnknownSVal PtrEQ =
 | 
						|
    svalBuilder.evalEQ(state, arg0Val, svalBuilder.makeNull());
 | 
						|
 | 
						|
  // Get the size argument. If there is no size arg then give up.
 | 
						|
  const Expr *Arg1 = CE->getArg(1);
 | 
						|
  if (!Arg1)
 | 
						|
    return;
 | 
						|
 | 
						|
  // Get the value of the size argument.
 | 
						|
  DefinedOrUnknownSVal Arg1Val = 
 | 
						|
    cast<DefinedOrUnknownSVal>(state->getSVal(Arg1));
 | 
						|
 | 
						|
  // Compare the size argument to 0.
 | 
						|
  DefinedOrUnknownSVal SizeZero =
 | 
						|
    svalBuilder.evalEQ(state, Arg1Val,
 | 
						|
                       svalBuilder.makeIntValWithPtrWidth(0, false));
 | 
						|
 | 
						|
  // If the ptr is NULL and the size is not 0, the call is equivalent to 
 | 
						|
  // malloc(size).
 | 
						|
  const GRState *stateEqual = state->assume(PtrEQ, true);
 | 
						|
  if (stateEqual && state->assume(SizeZero, false)) {
 | 
						|
    // Hack: set the NULL symbolic region to released to suppress false warning.
 | 
						|
    // In the future we should add more states for allocated regions, e.g., 
 | 
						|
    // CheckedNull, CheckedNonNull.
 | 
						|
    
 | 
						|
    SymbolRef Sym = arg0Val.getAsLocSymbol();
 | 
						|
    if (Sym)
 | 
						|
      stateEqual = stateEqual->set<RegionState>(Sym, RefState::getReleased(CE));
 | 
						|
 | 
						|
    const GRState *stateMalloc = MallocMemAux(C, CE, CE->getArg(1), 
 | 
						|
                                              UndefinedVal(), stateEqual);
 | 
						|
    C.addTransition(stateMalloc);
 | 
						|
  }
 | 
						|
 | 
						|
  if (const GRState *stateNotEqual = state->assume(PtrEQ, false)) {
 | 
						|
    // If the size is 0, free the memory.
 | 
						|
    if (const GRState *stateSizeZero = stateNotEqual->assume(SizeZero, true))
 | 
						|
      if (const GRState *stateFree = 
 | 
						|
          FreeMemAux(C, CE, stateSizeZero, 0, false)) {
 | 
						|
 | 
						|
        // Add the state transition to set input pointer argument to be free.
 | 
						|
        C.addTransition(stateFree);
 | 
						|
 | 
						|
        // Bind the return value to UndefinedVal because it is now free.
 | 
						|
        C.addTransition(stateFree->BindExpr(CE, UndefinedVal(), true));
 | 
						|
      }
 | 
						|
    if (const GRState *stateSizeNotZero = stateNotEqual->assume(SizeZero,false))
 | 
						|
      if (const GRState *stateFree = FreeMemAux(C, CE, stateSizeNotZero,
 | 
						|
                                                0, false)) {
 | 
						|
        // FIXME: We should copy the content of the original buffer.
 | 
						|
        const GRState *stateRealloc = MallocMemAux(C, CE, CE->getArg(1), 
 | 
						|
                                                   UnknownVal(), stateFree);
 | 
						|
        C.addTransition(stateRealloc);
 | 
						|
      }
 | 
						|
  }
 | 
						|
}
 | 
						|
 | 
						|
void MallocChecker::CallocMem(CheckerContext &C, const CallExpr *CE) {
 | 
						|
  const GRState *state = C.getState();
 | 
						|
  SValBuilder &svalBuilder = C.getSValBuilder();
 | 
						|
 | 
						|
  SVal count = state->getSVal(CE->getArg(0));
 | 
						|
  SVal elementSize = state->getSVal(CE->getArg(1));
 | 
						|
  SVal TotalSize = svalBuilder.evalBinOp(state, BO_Mul, count, elementSize,
 | 
						|
                                        svalBuilder.getContext().getSizeType());  
 | 
						|
  SVal zeroVal = svalBuilder.makeZeroVal(svalBuilder.getContext().CharTy);
 | 
						|
 | 
						|
  C.addTransition(MallocMemAux(C, CE, TotalSize, zeroVal, state));
 | 
						|
}
 | 
						|
 | 
						|
void MallocChecker::checkDeadSymbols(SymbolReaper &SymReaper,
 | 
						|
                                     CheckerContext &C) const
 | 
						|
{
 | 
						|
  if (!SymReaper.hasDeadSymbols())
 | 
						|
    return;
 | 
						|
 | 
						|
  const GRState *state = C.getState();
 | 
						|
  RegionStateTy RS = state->get<RegionState>();
 | 
						|
  RegionStateTy::Factory &F = state->get_context<RegionState>();
 | 
						|
 | 
						|
  for (RegionStateTy::iterator I = RS.begin(), E = RS.end(); I != E; ++I) {
 | 
						|
    if (SymReaper.isDead(I->first)) {
 | 
						|
      if (I->second.isAllocated()) {
 | 
						|
        if (ExplodedNode *N = C.generateNode()) {
 | 
						|
          if (!BT_Leak)
 | 
						|
            BT_Leak.reset(new BuiltinBug("Memory leak",
 | 
						|
                    "Allocated memory never released. Potential memory leak."));
 | 
						|
          // FIXME: where it is allocated.
 | 
						|
          BugReport *R = new BugReport(*BT_Leak, BT_Leak->getDescription(), N);
 | 
						|
          C.EmitReport(R);
 | 
						|
        }
 | 
						|
      }
 | 
						|
 | 
						|
      // Remove the dead symbol from the map.
 | 
						|
      RS = F.remove(RS, I->first);
 | 
						|
    }
 | 
						|
  }
 | 
						|
  C.generateNode(state->set<RegionState>(RS));
 | 
						|
}
 | 
						|
 | 
						|
void MallocChecker::checkEndPath(EndOfFunctionNodeBuilder &B,
 | 
						|
                                 ExprEngine &Eng) const {
 | 
						|
  const GRState *state = B.getState();
 | 
						|
  RegionStateTy M = state->get<RegionState>();
 | 
						|
 | 
						|
  for (RegionStateTy::iterator I = M.begin(), E = M.end(); I != E; ++I) {
 | 
						|
    RefState RS = I->second;
 | 
						|
    if (RS.isAllocated()) {
 | 
						|
      ExplodedNode *N = B.generateNode(state);
 | 
						|
      if (N) {
 | 
						|
        if (!BT_Leak)
 | 
						|
          BT_Leak.reset(new BuiltinBug("Memory leak",
 | 
						|
                    "Allocated memory never released. Potential memory leak."));
 | 
						|
        BugReport *R = new BugReport(*BT_Leak, BT_Leak->getDescription(), N);
 | 
						|
        Eng.getBugReporter().EmitReport(R);
 | 
						|
      }
 | 
						|
    }
 | 
						|
  }
 | 
						|
}
 | 
						|
 | 
						|
void MallocChecker::checkPreStmt(const ReturnStmt *S, CheckerContext &C) const {
 | 
						|
  const Expr *retExpr = S->getRetValue();
 | 
						|
  if (!retExpr)
 | 
						|
    return;
 | 
						|
 | 
						|
  const GRState *state = C.getState();
 | 
						|
 | 
						|
  SymbolRef Sym = state->getSVal(retExpr).getAsSymbol();
 | 
						|
  if (!Sym)
 | 
						|
    return;
 | 
						|
 | 
						|
  const RefState *RS = state->get<RegionState>(Sym);
 | 
						|
  if (!RS)
 | 
						|
    return;
 | 
						|
 | 
						|
  // FIXME: check other cases.
 | 
						|
  if (RS->isAllocated())
 | 
						|
    state = state->set<RegionState>(Sym, RefState::getEscaped(S));
 | 
						|
 | 
						|
  C.addTransition(state);
 | 
						|
}
 | 
						|
 | 
						|
const GRState *MallocChecker::evalAssume(const GRState *state, SVal Cond, 
 | 
						|
                                         bool Assumption) const {
 | 
						|
  // If a symblic region is assumed to NULL, set its state to AllocateFailed.
 | 
						|
  // FIXME: should also check symbols assumed to non-null.
 | 
						|
 | 
						|
  RegionStateTy RS = state->get<RegionState>();
 | 
						|
 | 
						|
  for (RegionStateTy::iterator I = RS.begin(), E = RS.end(); I != E; ++I) {
 | 
						|
    // If the symbol is assumed to NULL, this will return an APSInt*.
 | 
						|
    if (state->getSymVal(I.getKey()))
 | 
						|
      state = state->set<RegionState>(I.getKey(),RefState::getAllocateFailed());
 | 
						|
  }
 | 
						|
 | 
						|
  return state;
 | 
						|
}
 | 
						|
 | 
						|
// Check if the location is a freed symbolic region.
 | 
						|
void MallocChecker::checkLocation(SVal l, bool isLoad,CheckerContext &C) const {
 | 
						|
  SymbolRef Sym = l.getLocSymbolInBase();
 | 
						|
  if (Sym) {
 | 
						|
    const RefState *RS = C.getState()->get<RegionState>(Sym);
 | 
						|
    if (RS && RS->isReleased()) {
 | 
						|
      if (ExplodedNode *N = C.generateNode()) {
 | 
						|
        if (!BT_UseFree)
 | 
						|
          BT_UseFree.reset(new BuiltinBug("Use dynamically allocated memory "
 | 
						|
                                          "after it is freed."));
 | 
						|
 | 
						|
        BugReport *R = new BugReport(*BT_UseFree, BT_UseFree->getDescription(),
 | 
						|
                                     N);
 | 
						|
        C.EmitReport(R);
 | 
						|
      }
 | 
						|
    }
 | 
						|
  }
 | 
						|
}
 | 
						|
 | 
						|
void MallocChecker::checkBind(SVal location, SVal val,CheckerContext &C) const {
 | 
						|
  // The PreVisitBind implements the same algorithm as already used by the 
 | 
						|
  // Objective C ownership checker: if the pointer escaped from this scope by 
 | 
						|
  // assignment, let it go.  However, assigning to fields of a stack-storage 
 | 
						|
  // structure does not transfer ownership.
 | 
						|
 | 
						|
  const GRState *state = C.getState();
 | 
						|
  DefinedOrUnknownSVal l = cast<DefinedOrUnknownSVal>(location);
 | 
						|
 | 
						|
  // Check for null dereferences.
 | 
						|
  if (!isa<Loc>(l))
 | 
						|
    return;
 | 
						|
 | 
						|
  // Before checking if the state is null, check if 'val' has a RefState.
 | 
						|
  // Only then should we check for null and bifurcate the state.
 | 
						|
  SymbolRef Sym = val.getLocSymbolInBase();
 | 
						|
  if (Sym) {
 | 
						|
    if (const RefState *RS = state->get<RegionState>(Sym)) {
 | 
						|
      // If ptr is NULL, no operation is performed.
 | 
						|
      const GRState *notNullState, *nullState;
 | 
						|
      llvm::tie(notNullState, nullState) = state->assume(l);
 | 
						|
 | 
						|
      // Generate a transition for 'nullState' to record the assumption
 | 
						|
      // that the state was null.
 | 
						|
      if (nullState)
 | 
						|
        C.addTransition(nullState);
 | 
						|
 | 
						|
      if (!notNullState)
 | 
						|
        return;
 | 
						|
 | 
						|
      if (RS->isAllocated()) {
 | 
						|
        // Something we presently own is being assigned somewhere.
 | 
						|
        const MemRegion *AR = location.getAsRegion();
 | 
						|
        if (!AR)
 | 
						|
          return;
 | 
						|
        AR = AR->StripCasts()->getBaseRegion();
 | 
						|
        do {
 | 
						|
          // If it is on the stack, we still own it.
 | 
						|
          if (AR->hasStackNonParametersStorage())
 | 
						|
            break;
 | 
						|
 | 
						|
          // If the state can't represent this binding, we still own it.
 | 
						|
          if (notNullState == (notNullState->bindLoc(cast<Loc>(location),
 | 
						|
                                                     UnknownVal())))
 | 
						|
            break;
 | 
						|
 | 
						|
          // We no longer own this pointer.
 | 
						|
          notNullState =
 | 
						|
            notNullState->set<RegionState>(Sym,
 | 
						|
                                        RefState::getRelinquished(C.getStmt()));
 | 
						|
        }
 | 
						|
        while (false);
 | 
						|
      }
 | 
						|
      C.addTransition(notNullState);
 | 
						|
    }
 | 
						|
  }
 | 
						|
}
 | 
						|
 | 
						|
void ento::registerMallocChecker(CheckerManager &mgr) {
 | 
						|
  mgr.registerChecker<MallocChecker>();
 | 
						|
}
 |