1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
| //== DynamicTypeChecker.cpp ------------------------------------ -*- C++ -*--=//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This checker looks for cases where the dynamic type of an object is unrelated
// to its static type. The type information utilized by this check is collected
// by the DynamicTypePropagation checker. This check does not report any type
// error for ObjC Generic types, in order to avoid duplicate erros from the
// ObjC Generics checker. This checker is not supposed to modify the program
// state, it is just the observer of the type information provided by other
// checkers.
//
//===----------------------------------------------------------------------===//
#include "clang/StaticAnalyzer/Checkers/BuiltinCheckerRegistration.h"
#include "clang/StaticAnalyzer/Core/BugReporter/BugType.h"
#include "clang/StaticAnalyzer/Core/Checker.h"
#include "clang/StaticAnalyzer/Core/CheckerManager.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/CallEvent.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/DynamicType.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/ProgramStateTrait.h"
using namespace clang;
using namespace ento;
namespace {
class DynamicTypeChecker : public Checker<check::PostStmt<ImplicitCastExpr>> {
mutable std::unique_ptr<BugType> BT;
void initBugType() const {
if (!BT)
BT.reset(
new BugType(this, "Dynamic and static type mismatch", "Type Error"));
}
class DynamicTypeBugVisitor : public BugReporterVisitor {
public:
DynamicTypeBugVisitor(const MemRegion *Reg) : Reg(Reg) {}
void Profile(llvm::FoldingSetNodeID &ID) const override {
static int X = 0;
ID.AddPointer(&X);
ID.AddPointer(Reg);
}
PathDiagnosticPieceRef VisitNode(const ExplodedNode *N,
BugReporterContext &BRC,
PathSensitiveBugReport &BR) override;
private:
// The tracked region.
const MemRegion *Reg;
};
void reportTypeError(QualType DynamicType, QualType StaticType,
const MemRegion *Reg, const Stmt *ReportedNode,
CheckerContext &C) const;
public:
void checkPostStmt(const ImplicitCastExpr *CE, CheckerContext &C) const;
};
}
void DynamicTypeChecker::reportTypeError(QualType DynamicType,
QualType StaticType,
const MemRegion *Reg,
const Stmt *ReportedNode,
CheckerContext &C) const {
initBugType();
SmallString<192> Buf;
llvm::raw_svector_ostream OS(Buf);
OS << "Object has a dynamic type '";
QualType::print(DynamicType.getTypePtr(), Qualifiers(), OS, C.getLangOpts(),
llvm::Twine());
OS << "' which is incompatible with static type '";
QualType::print(StaticType.getTypePtr(), Qualifiers(), OS, C.getLangOpts(),
llvm::Twine());
OS << "'";
auto R = std::make_unique<PathSensitiveBugReport>(
*BT, OS.str(), C.generateNonFatalErrorNode());
R->markInteresting(Reg);
R->addVisitor(std::make_unique<DynamicTypeBugVisitor>(Reg));
R->addRange(ReportedNode->getSourceRange());
C.emitReport(std::move(R));
}
PathDiagnosticPieceRef DynamicTypeChecker::DynamicTypeBugVisitor::VisitNode(
const ExplodedNode *N, BugReporterContext &BRC, PathSensitiveBugReport &) {
ProgramStateRef State = N->getState();
ProgramStateRef StatePrev = N->getFirstPred()->getState();
DynamicTypeInfo TrackedType = getDynamicTypeInfo(State, Reg);
DynamicTypeInfo TrackedTypePrev = getDynamicTypeInfo(StatePrev, Reg);
if (!TrackedType.isValid())
return nullptr;
if (TrackedTypePrev.isValid() &&
TrackedTypePrev.getType() == TrackedType.getType())
return nullptr;
// Retrieve the associated statement.
const Stmt *S = N->getStmtForDiagnostics();
if (!S)
return nullptr;
const LangOptions &LangOpts = BRC.getASTContext().getLangOpts();
SmallString<256> Buf;
llvm::raw_svector_ostream OS(Buf);
OS << "Type '";
QualType::print(TrackedType.getType().getTypePtr(), Qualifiers(), OS,
LangOpts, llvm::Twine());
OS << "' is inferred from ";
if (const auto *ExplicitCast = dyn_cast<ExplicitCastExpr>(S)) {
OS << "explicit cast (from '";
QualType::print(ExplicitCast->getSubExpr()->getType().getTypePtr(),
Qualifiers(), OS, LangOpts, llvm::Twine());
OS << "' to '";
QualType::print(ExplicitCast->getType().getTypePtr(), Qualifiers(), OS,
LangOpts, llvm::Twine());
OS << "')";
} else if (const auto *ImplicitCast = dyn_cast<ImplicitCastExpr>(S)) {
OS << "implicit cast (from '";
QualType::print(ImplicitCast->getSubExpr()->getType().getTypePtr(),
Qualifiers(), OS, LangOpts, llvm::Twine());
OS << "' to '";
QualType::print(ImplicitCast->getType().getTypePtr(), Qualifiers(), OS,
LangOpts, llvm::Twine());
OS << "')";
} else {
OS << "this context";
}
// Generate the extra diagnostic.
PathDiagnosticLocation Pos(S, BRC.getSourceManager(),
N->getLocationContext());
return std::make_shared<PathDiagnosticEventPiece>(Pos, OS.str(), true);
}
static bool hasDefinition(const ObjCObjectPointerType *ObjPtr) {
const ObjCInterfaceDecl *Decl = ObjPtr->getInterfaceDecl();
if (!Decl)
return false;
return Decl->getDefinition();
}
// TODO: consider checking explicit casts?
void DynamicTypeChecker::checkPostStmt(const ImplicitCastExpr *CE,
CheckerContext &C) const {
// TODO: C++ support.
if (CE->getCastKind() != CK_BitCast)
return;
const MemRegion *Region = C.getSVal(CE).getAsRegion();
if (!Region)
return;
ProgramStateRef State = C.getState();
DynamicTypeInfo DynTypeInfo = getDynamicTypeInfo(State, Region);
if (!DynTypeInfo.isValid())
return;
QualType DynType = DynTypeInfo.getType();
QualType StaticType = CE->getType();
const auto *DynObjCType = DynType->getAs<ObjCObjectPointerType>();
const auto *StaticObjCType = StaticType->getAs<ObjCObjectPointerType>();
if (!DynObjCType || !StaticObjCType)
return;
if (!hasDefinition(DynObjCType) || !hasDefinition(StaticObjCType))
return;
ASTContext &ASTCtxt = C.getASTContext();
// Strip kindeofness to correctly detect subtyping relationships.
DynObjCType = DynObjCType->stripObjCKindOfTypeAndQuals(ASTCtxt);
StaticObjCType = StaticObjCType->stripObjCKindOfTypeAndQuals(ASTCtxt);
// Specialized objects are handled by the generics checker.
if (StaticObjCType->isSpecialized())
return;
if (ASTCtxt.canAssignObjCInterfaces(StaticObjCType, DynObjCType))
return;
if (DynTypeInfo.canBeASubClass() &&
ASTCtxt.canAssignObjCInterfaces(DynObjCType, StaticObjCType))
return;
reportTypeError(DynType, StaticType, Region, CE, C);
}
void ento::registerDynamicTypeChecker(CheckerManager &mgr) {
mgr.registerChecker<DynamicTypeChecker>();
}
bool ento::shouldRegisterDynamicTypeChecker(const LangOptions &LO) {
return true;
}
|