clang  12.0.0git
ObjCAtSyncChecker.cpp
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1 //== ObjCAtSyncChecker.cpp - nil mutex checker for @synchronized -*- C++ -*--=//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // This defines ObjCAtSyncChecker, a builtin check that checks for null pointers
10 // used as mutexes for @synchronized.
11 //
12 //===----------------------------------------------------------------------===//
13 
15 #include "clang/AST/StmtObjC.h"
21 
22 using namespace clang;
23 using namespace ento;
24 
25 namespace {
26 class ObjCAtSyncChecker
27  : public Checker< check::PreStmt<ObjCAtSynchronizedStmt> > {
28  mutable std::unique_ptr<BuiltinBug> BT_null;
29  mutable std::unique_ptr<BuiltinBug> BT_undef;
30 
31 public:
32  void checkPreStmt(const ObjCAtSynchronizedStmt *S, CheckerContext &C) const;
33 };
34 } // end anonymous namespace
35 
36 void ObjCAtSyncChecker::checkPreStmt(const ObjCAtSynchronizedStmt *S,
37  CheckerContext &C) const {
38 
39  const Expr *Ex = S->getSynchExpr();
40  ProgramStateRef state = C.getState();
41  SVal V = C.getSVal(Ex);
42 
43  // Uninitialized value used for the mutex?
44  if (V.getAs<UndefinedVal>()) {
45  if (ExplodedNode *N = C.generateErrorNode()) {
46  if (!BT_undef)
47  BT_undef.reset(new BuiltinBug(this, "Uninitialized value used as mutex "
48  "for @synchronized"));
49  auto report = std::make_unique<PathSensitiveBugReport>(
50  *BT_undef, BT_undef->getDescription(), N);
51  bugreporter::trackExpressionValue(N, Ex, *report);
52  C.emitReport(std::move(report));
53  }
54  return;
55  }
56 
57  if (V.isUnknown())
58  return;
59 
60  // Check for null mutexes.
61  ProgramStateRef notNullState, nullState;
62  std::tie(notNullState, nullState) = state->assume(V.castAs<DefinedSVal>());
63 
64  if (nullState) {
65  if (!notNullState) {
66  // Generate an error node. This isn't a sink since
67  // a null mutex just means no synchronization occurs.
68  if (ExplodedNode *N = C.generateNonFatalErrorNode(nullState)) {
69  if (!BT_null)
70  BT_null.reset(new BuiltinBug(
71  this, "Nil value used as mutex for @synchronized() "
72  "(no synchronization will occur)"));
73  auto report = std::make_unique<PathSensitiveBugReport>(
74  *BT_null, BT_null->getDescription(), N);
75  bugreporter::trackExpressionValue(N, Ex, *report);
76 
77  C.emitReport(std::move(report));
78  return;
79  }
80  }
81  // Don't add a transition for 'nullState'. If the value is
82  // under-constrained to be null or non-null, assume it is non-null
83  // afterwards.
84  }
85 
86  if (notNullState)
87  C.addTransition(notNullState);
88 }
89 
90 void ento::registerObjCAtSyncChecker(CheckerManager &mgr) {
91  mgr.registerChecker<ObjCAtSyncChecker>();
92 }
93 
94 bool ento::shouldRegisterObjCAtSyncChecker(const CheckerManager &mgr) {
95  const LangOptions &LO = mgr.getLangOpts();
96  return LO.ObjC;
97 }
IntrusiveRefCntPtr< const ProgramState > ProgramStateRef
Defines the Objective-C statement AST node classes.
Keeps track of the various options that can be enabled, which controls the dialect of C or C++ that i...
Definition: LangOptions.h:54
i32 captured_struct **param SharedsTy A type which contains references the shared variables *param Shareds Context with the list of shared variables from the p *TaskFunction *param Data Additional data for task generation like final * state
This represents one expression.
Definition: Expr.h:110
#define V(N, I)
Definition: ASTContext.h:2899
Represents Objective-C&#39;s @synchronized statement.
Definition: StmtObjC.h:277
Dataflow Directional Tag Classes.
const Expr * getSynchExpr() const
Definition: StmtObjC.h:305