1// SmartPtrChecker.cpp - Check for smart pointer dereference - 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 file defines a checker that check for null dereference of C++ smart
10// pointer.
11//
12//===----------------------------------------------------------------------===//
13#include "SmartPtr.h"
14
15#include "clang/AST/DeclCXX.h"
16#include "clang/AST/ExprCXX.h"
17#include "clang/AST/Type.h"
18#include "clang/StaticAnalyzer/Checkers/BuiltinCheckerRegistration.h"
19#include "clang/StaticAnalyzer/Core/BugReporter/BugType.h"
20#include "clang/StaticAnalyzer/Core/Checker.h"
21#include "clang/StaticAnalyzer/Core/CheckerManager.h"
22#include "clang/StaticAnalyzer/Core/PathSensitive/CallEvent.h"
23#include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
24#include "clang/StaticAnalyzer/Core/PathSensitive/SVals.h"
25#include "clang/StaticAnalyzer/Core/PathSensitive/SymExpr.h"
26#include "llvm/ADT/StringRef.h"
27
28using namespace clang;
29using namespace ento;
30
31namespace {
32
33static const BugType *NullDereferenceBugTypePtr;
34
35class SmartPtrChecker : public Checker<check::PreCall> {
36public:
37  void checkPreCall(const CallEvent &Call, CheckerContext &C) const;
38  BugType NullDereferenceBugType{this, "Null SmartPtr dereference",
39                                 "C++ Smart Pointer"};
40
41private:
42  void reportBug(CheckerContext &C, const MemRegion *DerefRegion,
43                 const CallEvent &Call) const;
44  void explainDereference(llvm::raw_ostream &OS, const MemRegion *DerefRegion,
45                          const CallEvent &Call) const;
46};
47} // end of anonymous namespace
48
49// Define the inter-checker API.
50namespace clang {
51namespace ento {
52namespace smartptr {
53
54const BugType *getNullDereferenceBugType() { return NullDereferenceBugTypePtr; }
55
56} // namespace smartptr
57} // namespace ento
58} // namespace clang
59
60void SmartPtrChecker::checkPreCall(const CallEvent &Call,
61                                   CheckerContext &C) const {
62  if (!smartptr::isStdSmartPtrCall(Call))
63    return;
64  ProgramStateRef State = C.getState();
65  const auto *OC = dyn_cast<CXXMemberOperatorCall>(&Call);
66  if (!OC)
67    return;
68  const MemRegion *ThisRegion = OC->getCXXThisVal().getAsRegion();
69  if (!ThisRegion)
70    return;
71
72  OverloadedOperatorKind OOK = OC->getOverloadedOperator();
73  if (OOK == OO_Star || OOK == OO_Arrow) {
74    if (smartptr::isNullSmartPtr(State, ThisRegion))
75      reportBug(C, ThisRegion, Call);
76  }
77}
78
79void SmartPtrChecker::reportBug(CheckerContext &C, const MemRegion *DerefRegion,
80                                const CallEvent &Call) const {
81  ExplodedNode *ErrNode = C.generateErrorNode();
82  if (!ErrNode)
83    return;
84  llvm::SmallString<128> Str;
85  llvm::raw_svector_ostream OS(Str);
86  explainDereference(OS, DerefRegion, Call);
87  auto R = std::make_unique<PathSensitiveBugReport>(NullDereferenceBugType,
88                                                    OS.str(), ErrNode);
89  R->markInteresting(DerefRegion);
90  C.emitReport(std::move(R));
91}
92
93void SmartPtrChecker::explainDereference(llvm::raw_ostream &OS,
94                                         const MemRegion *DerefRegion,
95                                         const CallEvent &Call) const {
96  OS << "Dereference of null smart pointer ";
97  DerefRegion->printPretty(OS);
98}
99
100void ento::registerSmartPtrChecker(CheckerManager &Mgr) {
101  SmartPtrChecker *Checker = Mgr.registerChecker<SmartPtrChecker>();
102  NullDereferenceBugTypePtr = &Checker->NullDereferenceBugType;
103}
104
105bool ento::shouldRegisterSmartPtrChecker(const CheckerManager &mgr) {
106  const LangOptions &LO = mgr.getLangOpts();
107  return LO.CPlusPlus;
108}
109