1 //===-- DeleteWithNonVirtualDtorChecker.cpp -----------------------*- 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 // Defines a checker for the OOP52-CPP CERT rule: Do not delete a polymorphic
11 // object without a virtual destructor.
12 //
13 // Diagnostic flags -Wnon-virtual-dtor and -Wdelete-non-virtual-dtor report if
14 // an object with a virtual function but a non-virtual destructor exists or is
15 // deleted, respectively.
16 //
17 // This check exceeds them by comparing the dynamic and static types of the
18 // object at the point of destruction and only warns if it happens through a
19 // pointer to a base type without a virtual destructor. The check places a note
20 // at the last point where the conversion from derived to base happened.
21 //
22 //===----------------------------------------------------------------------===//
23
24 #include "clang/StaticAnalyzer/Checkers/BuiltinCheckerRegistration.h"
25 #include "clang/StaticAnalyzer/Core/BugReporter/BugReporter.h"
26 #include "clang/StaticAnalyzer/Core/BugReporter/BugType.h"
27 #include "clang/StaticAnalyzer/Core/Checker.h"
28 #include "clang/StaticAnalyzer/Core/CheckerManager.h"
29 #include "clang/StaticAnalyzer/Core/PathSensitive/CallEvent.h"
30 #include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
31 #include "clang/StaticAnalyzer/Core/PathSensitive/DynamicTypeMap.h"
32 #include "clang/StaticAnalyzer/Core/PathSensitive/ProgramStateTrait.h"
33
34 using namespace clang;
35 using namespace ento;
36
37 namespace {
38 class DeleteWithNonVirtualDtorChecker
39 : public Checker<check::PreStmt<CXXDeleteExpr>> {
40 mutable std::unique_ptr<BugType> BT;
41
42 class DeleteBugVisitor : public BugReporterVisitor {
43 public:
DeleteBugVisitor()44 DeleteBugVisitor() : Satisfied(false) {}
Profile(llvm::FoldingSetNodeID & ID) const45 void Profile(llvm::FoldingSetNodeID &ID) const override {
46 static int X = 0;
47 ID.AddPointer(&X);
48 }
49 std::shared_ptr<PathDiagnosticPiece> VisitNode(const ExplodedNode *N,
50 BugReporterContext &BRC,
51 BugReport &BR) override;
52
53 private:
54 bool Satisfied;
55 };
56
57 public:
58 void checkPreStmt(const CXXDeleteExpr *DE, CheckerContext &C) const;
59 };
60 } // end anonymous namespace
61
checkPreStmt(const CXXDeleteExpr * DE,CheckerContext & C) const62 void DeleteWithNonVirtualDtorChecker::checkPreStmt(const CXXDeleteExpr *DE,
63 CheckerContext &C) const {
64 const Expr *DeletedObj = DE->getArgument();
65 const MemRegion *MR = C.getSVal(DeletedObj).getAsRegion();
66 if (!MR)
67 return;
68
69 const auto *BaseClassRegion = MR->getAs<TypedValueRegion>();
70 const auto *DerivedClassRegion = MR->getBaseRegion()->getAs<SymbolicRegion>();
71 if (!BaseClassRegion || !DerivedClassRegion)
72 return;
73
74 const auto *BaseClass = BaseClassRegion->getValueType()->getAsCXXRecordDecl();
75 const auto *DerivedClass =
76 DerivedClassRegion->getSymbol()->getType()->getPointeeCXXRecordDecl();
77 if (!BaseClass || !DerivedClass)
78 return;
79
80 if (!BaseClass->hasDefinition() || !DerivedClass->hasDefinition())
81 return;
82
83 if (BaseClass->getDestructor()->isVirtual())
84 return;
85
86 if (!DerivedClass->isDerivedFrom(BaseClass))
87 return;
88
89 if (!BT)
90 BT.reset(new BugType(this,
91 "Destruction of a polymorphic object with no "
92 "virtual destructor",
93 "Logic error"));
94
95 ExplodedNode *N = C.generateNonFatalErrorNode();
96 auto R = llvm::make_unique<BugReport>(*BT, BT->getName(), N);
97
98 // Mark region of problematic base class for later use in the BugVisitor.
99 R->markInteresting(BaseClassRegion);
100 R->addVisitor(llvm::make_unique<DeleteBugVisitor>());
101 C.emitReport(std::move(R));
102 }
103
104 std::shared_ptr<PathDiagnosticPiece>
VisitNode(const ExplodedNode * N,BugReporterContext & BRC,BugReport & BR)105 DeleteWithNonVirtualDtorChecker::DeleteBugVisitor::VisitNode(
106 const ExplodedNode *N, BugReporterContext &BRC,
107 BugReport &BR) {
108 // Stop traversal after the first conversion was found on a path.
109 if (Satisfied)
110 return nullptr;
111
112 const Stmt *S = PathDiagnosticLocation::getStmt(N);
113 if (!S)
114 return nullptr;
115
116 const auto *CastE = dyn_cast<CastExpr>(S);
117 if (!CastE)
118 return nullptr;
119
120 // Only interested in DerivedToBase implicit casts.
121 // Explicit casts can have different CastKinds.
122 if (const auto *ImplCastE = dyn_cast<ImplicitCastExpr>(CastE)) {
123 if (ImplCastE->getCastKind() != CK_DerivedToBase)
124 return nullptr;
125 }
126
127 // Region associated with the current cast expression.
128 const MemRegion *M = N->getSVal(CastE).getAsRegion();
129 if (!M)
130 return nullptr;
131
132 // Check if target region was marked as problematic previously.
133 if (!BR.isInteresting(M))
134 return nullptr;
135
136 // Stop traversal on this path.
137 Satisfied = true;
138
139 SmallString<256> Buf;
140 llvm::raw_svector_ostream OS(Buf);
141 OS << "Conversion from derived to base happened here";
142 PathDiagnosticLocation Pos(S, BRC.getSourceManager(),
143 N->getLocationContext());
144 return std::make_shared<PathDiagnosticEventPiece>(Pos, OS.str(), true,
145 nullptr);
146 }
147
registerDeleteWithNonVirtualDtorChecker(CheckerManager & mgr)148 void ento::registerDeleteWithNonVirtualDtorChecker(CheckerManager &mgr) {
149 mgr.registerChecker<DeleteWithNonVirtualDtorChecker>();
150 }
151