UndefinedAssignmentChecker.cpp source code [clang_source_code/lib/StaticAnalyzer/Checkers/UndefinedAssignmentChecker.cpp]

1	//===--- UndefinedAssignmentChecker.h ---------------------------- 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 UndefinedAssignmentChecker, a builtin check in ExprEngine that
10	// checks for assigning undefined values.
11	//
12	//===----------------------------------------------------------------------===//
13
14	#include "clang/StaticAnalyzer/Checkers/BuiltinCheckerRegistration.h"
15	#include "clang/StaticAnalyzer/Core/BugReporter/BugType.h"
16	#include "clang/StaticAnalyzer/Core/Checker.h"
17	#include "clang/StaticAnalyzer/Core/CheckerManager.h"
18	#include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
19
20	using namespace clang;
21	using namespace ento;
22
23	namespace {
24	class UndefinedAssignmentChecker
25	: public Checker<check::Bind> {
26	mutable std::unique_ptr<BugType> BT;
27
28	public:
29	void checkBind(SVal location, SVal val, const Stmt *S,
30	CheckerContext &C) const;
31	};
32	}
33
34	void UndefinedAssignmentChecker::checkBind(SVal location, SVal val,
35	const Stmt *StoreE,
36	CheckerContext &C) const {
37	if (!val.isUndef())
38	return;
39
40	// Do not report assignments of uninitialized values inside swap functions.
41	// This should allow to swap partially uninitialized structs
42	// (radar://14129997)
43	if (const FunctionDecl *EnclosingFunctionDecl =
44	dyn_cast<FunctionDecl>(C.getStackFrame()->getDecl()))
45	if (C.getCalleeName(EnclosingFunctionDecl) == "swap")
46	return;
47
48	ExplodedNode *N = C.generateErrorNode();
49
50	if (!N)
51	return;
52
53	static const char *const DefaultMsg =
54	"Assigned value is garbage or undefined";
55	if (!BT)
56	BT.reset(new BuiltinBug(this, DefaultMsg));
57
58	// Generate a report for this bug.
59	llvm::SmallString<128> Str;
60	llvm::raw_svector_ostream OS(Str);
61
62	const Expr *ex = nullptr;
63
64	while (StoreE) {
65	if (const UnaryOperator *U = dyn_cast<UnaryOperator>(StoreE)) {
66	OS << "The expression is an uninitialized value. "
67	"The computed value will also be garbage";
68
69	ex = U->getSubExpr();
70	break;
71	}
72
73	if (const BinaryOperator *B = dyn_cast<BinaryOperator>(StoreE)) {
74	if (B->isCompoundAssignmentOp()) {
75	if (C.getSVal(B->getLHS()).isUndef()) {
76	OS << "The left expression of the compound assignment is an "
77	"uninitialized value. The computed value will also be garbage";
78	ex = B->getLHS();
79	break;
80	}
81	}
82
83	ex = B->getRHS();
84	break;
85	}
86
87	if (const DeclStmt *DS = dyn_cast<DeclStmt>(StoreE)) {
88	const VarDecl *VD = dyn_cast<VarDecl>(DS->getSingleDecl());
89	ex = VD->getInit();
90	}
91
92	if (const auto *CD =
93	dyn_cast<CXXConstructorDecl>(C.getStackFrame()->getDecl())) {
94	if (CD->isImplicit()) {
95	for (auto I : CD->inits()) {
96	if (I->getInit()->IgnoreImpCasts() == StoreE) {
97	OS << "Value assigned to field '" << I->getMember()->getName()
98	<< "' in implicit constructor is garbage or undefined";
99	break;
100	}
101	}
102	}
103	}
104
105	break;
106	}
107
108	if (OS.str().empty())
109	OS << DefaultMsg;
110
111	auto R = llvm::make_unique<BugReport>(*BT, OS.str(), N);
112	if (ex) {
113	R->addRange(ex->getSourceRange());
114	bugreporter::trackExpressionValue(N, ex, *R);
115	}
116	C.emitReport(std::move(R));
117	}
118
119	void ento::registerUndefinedAssignmentChecker(CheckerManager &mgr) {
120	mgr.registerChecker<UndefinedAssignmentChecker>();
121	}
122
123	bool ento::shouldRegisterUndefinedAssignmentChecker(const LangOptions &LO) {
124	return true;
125	}
126

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