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
| //===- ReturnValueChecker - Applies guaranteed return values ----*- 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 defines ReturnValueChecker, which checks for calls with guaranteed
// boolean return value. It ensures the return value of each function call.
//
//===----------------------------------------------------------------------===//
#include "clang/StaticAnalyzer/Checkers/BuiltinCheckerRegistration.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/CheckerContext.h"
#include "llvm/ADT/Optional.h"
#include "llvm/ADT/SmallVector.h"
using namespace clang;
using namespace ento;
namespace {
class ReturnValueChecker : public Checker<check::PostCall, check::EndFunction> {
public:
// It sets the predefined invariant ('CDM') if the current call not break it.
void checkPostCall(const CallEvent &Call, CheckerContext &C) const;
// It reports whether a predefined invariant ('CDM') is broken.
void checkEndFunction(const ReturnStmt *RS, CheckerContext &C) const;
private:
// The pairs are in the following form: {{{class, call}}, return value}
const CallDescriptionMap<bool> CDM = {
// These are known in the LLVM project: 'Error()'
{{{"ARMAsmParser", "Error"}}, true},
{{{"HexagonAsmParser", "Error"}}, true},
{{{"LLLexer", "Error"}}, true},
{{{"LLParser", "Error"}}, true},
{{{"MCAsmParser", "Error"}}, true},
{{{"MCAsmParserExtension", "Error"}}, true},
{{{"TGParser", "Error"}}, true},
{{{"X86AsmParser", "Error"}}, true},
// 'TokError()'
{{{"LLParser", "TokError"}}, true},
{{{"MCAsmParser", "TokError"}}, true},
{{{"MCAsmParserExtension", "TokError"}}, true},
{{{"TGParser", "TokError"}}, true},
// 'error()'
{{{"MIParser", "error"}}, true},
{{{"WasmAsmParser", "error"}}, true},
{{{"WebAssemblyAsmParser", "error"}}, true},
// Other
{{{"AsmParser", "printError"}}, true}};
};
} // namespace
static std::string getName(const CallEvent &Call) {
std::string Name = "";
if (const auto *MD = dyn_cast<CXXMethodDecl>(Call.getDecl()))
if (const CXXRecordDecl *RD = MD->getParent())
Name += RD->getNameAsString() + "::";
Name += Call.getCalleeIdentifier()->getName();
return Name;
}
// The predefinitions ('CDM') could break due to the ever growing code base.
// Check for the expected invariants and see whether they apply.
static Optional<bool> isInvariantBreak(bool ExpectedValue, SVal ReturnV,
CheckerContext &C) {
auto ReturnDV = ReturnV.getAs<DefinedOrUnknownSVal>();
if (!ReturnDV)
return None;
if (ExpectedValue)
return C.getState()->isNull(*ReturnDV).isConstrainedTrue();
return C.getState()->isNull(*ReturnDV).isConstrainedFalse();
}
void ReturnValueChecker::checkPostCall(const CallEvent &Call,
CheckerContext &C) const {
const bool *RawExpectedValue = CDM.lookup(Call);
if (!RawExpectedValue)
return;
SVal ReturnV = Call.getReturnValue();
bool ExpectedValue = *RawExpectedValue;
Optional<bool> IsInvariantBreak = isInvariantBreak(ExpectedValue, ReturnV, C);
if (!IsInvariantBreak)
return;
// If the invariant is broken it is reported by 'checkEndFunction()'.
if (*IsInvariantBreak)
return;
std::string Name = getName(Call);
const NoteTag *CallTag = C.getNoteTag(
[Name, ExpectedValue](BugReport &) -> std::string {
SmallString<128> Msg;
llvm::raw_svector_ostream Out(Msg);
Out << '\'' << Name << "' returns "
<< (ExpectedValue ? "true" : "false");
return Out.str();
},
/*IsPrunable=*/true);
ProgramStateRef State = C.getState();
State = State->assume(ReturnV.castAs<DefinedOrUnknownSVal>(), ExpectedValue);
C.addTransition(State, CallTag);
}
void ReturnValueChecker::checkEndFunction(const ReturnStmt *RS,
CheckerContext &C) const {
if (!RS || !RS->getRetValue())
return;
// We cannot get the caller in the top-frame.
const StackFrameContext *SFC = C.getStackFrame();
if (C.getStackFrame()->inTopFrame())
return;
ProgramStateRef State = C.getState();
CallEventManager &CMgr = C.getStateManager().getCallEventManager();
CallEventRef<> Call = CMgr.getCaller(SFC, State);
if (!Call)
return;
const bool *RawExpectedValue = CDM.lookup(*Call);
if (!RawExpectedValue)
return;
SVal ReturnV = State->getSVal(RS->getRetValue(), C.getLocationContext());
bool ExpectedValue = *RawExpectedValue;
Optional<bool> IsInvariantBreak = isInvariantBreak(ExpectedValue, ReturnV, C);
if (!IsInvariantBreak)
return;
// If the invariant is appropriate it is reported by 'checkPostCall()'.
if (!*IsInvariantBreak)
return;
std::string Name = getName(*Call);
const NoteTag *CallTag = C.getNoteTag(
[Name, ExpectedValue](BugReport &BR) -> std::string {
SmallString<128> Msg;
llvm::raw_svector_ostream Out(Msg);
// The following is swapped because the invariant is broken.
Out << '\'' << Name << "' returns "
<< (ExpectedValue ? "false" : "true");
return Out.str();
},
/*IsPrunable=*/false);
C.addTransition(State, CallTag);
}
void ento::registerReturnValueChecker(CheckerManager &Mgr) {
Mgr.registerChecker<ReturnValueChecker>();
}
bool ento::shouldRegisterReturnValueChecker(const LangOptions &LO) {
return true;
}
|