clang 17.0.0git
UndefCapturedBlockVarChecker.cpp
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1// UndefCapturedBlockVarChecker.cpp - Uninitialized captured vars -*- 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 checker detects blocks that capture uninitialized values.
10//
11//===----------------------------------------------------------------------===//
12
14#include "clang/AST/Attr.h"
20#include "llvm/ADT/SmallString.h"
21#include "llvm/Support/raw_ostream.h"
22#include <optional>
23
24using namespace clang;
25using namespace ento;
26
27namespace {
28class UndefCapturedBlockVarChecker
29 : public Checker< check::PostStmt<BlockExpr> > {
30 mutable std::unique_ptr<BugType> BT;
31
32public:
33 void checkPostStmt(const BlockExpr *BE, CheckerContext &C) const;
34};
35} // end anonymous namespace
36
37static const DeclRefExpr *FindBlockDeclRefExpr(const Stmt *S,
38 const VarDecl *VD) {
39 if (const DeclRefExpr *BR = dyn_cast<DeclRefExpr>(S))
40 if (BR->getDecl() == VD)
41 return BR;
42
43 for (const Stmt *Child : S->children())
44 if (Child)
45 if (const DeclRefExpr *BR = FindBlockDeclRefExpr(Child, VD))
46 return BR;
47
48 return nullptr;
49}
50
51void
52UndefCapturedBlockVarChecker::checkPostStmt(const BlockExpr *BE,
53 CheckerContext &C) const {
54 if (!BE->getBlockDecl()->hasCaptures())
55 return;
56
57 ProgramStateRef state = C.getState();
58 auto *R = cast<BlockDataRegion>(C.getSVal(BE).getAsRegion());
59
60 BlockDataRegion::referenced_vars_iterator I = R->referenced_vars_begin(),
61 E = R->referenced_vars_end();
62
63 for (; I != E; ++I) {
64 // This VarRegion is the region associated with the block; we need
65 // the one associated with the encompassing context.
66 const VarRegion *VR = I.getCapturedRegion();
67 const VarDecl *VD = VR->getDecl();
68
69 if (VD->hasAttr<BlocksAttr>() || !VD->hasLocalStorage())
70 continue;
71
72 // Get the VarRegion associated with VD in the local stack frame.
73 if (std::optional<UndefinedVal> V =
74 state->getSVal(I.getOriginalRegion()).getAs<UndefinedVal>()) {
75 if (ExplodedNode *N = C.generateErrorNode()) {
76 if (!BT)
77 BT.reset(
78 new BuiltinBug(this, "uninitialized variable captured by block"));
79
80 // Generate a bug report.
82 llvm::raw_svector_ostream os(buf);
83
84 os << "Variable '" << VD->getName()
85 << "' is uninitialized when captured by block";
86
87 auto R = std::make_unique<PathSensitiveBugReport>(*BT, os.str(), N);
88 if (const Expr *Ex = FindBlockDeclRefExpr(BE->getBody(), VD))
89 R->addRange(Ex->getSourceRange());
91 {bugreporter::TrackingKind::Thorough,
92 /*EnableNullFPSuppression*/ false});
93 R->disablePathPruning();
94 // need location of block
95 C.emitReport(std::move(R));
96 }
97 }
98 }
99}
100
101void ento::registerUndefCapturedBlockVarChecker(CheckerManager &mgr) {
102 mgr.registerChecker<UndefCapturedBlockVarChecker>();
103}
104
105bool ento::shouldRegisterUndefCapturedBlockVarChecker(const CheckerManager &mgr) {
106 return true;
107}
#define V(N, I)
Definition: ASTContext.h:3217
static const DeclRefExpr * FindBlockDeclRefExpr(const Stmt *S, const VarDecl *VD)
bool hasCaptures() const
True if this block (or its nested blocks) captures anything of local storage from its enclosing scope...
Definition: Decl.h:4453
BlockExpr - Adaptor class for mixing a BlockDecl with expressions.
Definition: Expr.h:5975
const Stmt * getBody() const
Definition: Expr.cpp:2498
const BlockDecl * getBlockDecl() const
Definition: Expr.h:5987
A reference to a declared variable, function, enum, etc.
Definition: Expr.h:1238
bool hasAttr() const
Definition: DeclBase.h:560
This represents one expression.
Definition: Expr.h:110
StringRef getName() const
Get the name of identifier for this declaration as a StringRef.
Definition: Decl.h:274
Stmt - This represents one statement.
Definition: Stmt.h:72
Represents a variable declaration or definition.
Definition: Decl.h:913
bool hasLocalStorage() const
Returns true if a variable with function scope is a non-static local variable.
Definition: Decl.h:1141
LLVM_ATTRIBUTE_RETURNS_NONNULL const VarRegion * getCapturedRegion() const
Definition: MemRegion.h:718
LLVM_ATTRIBUTE_RETURNS_NONNULL const VarRegion * getOriginalRegion() const
Definition: MemRegion.h:723
CHECKER * registerChecker(AT &&... Args)
Used to register checkers.
const VarDecl * getDecl() const override=0
void trackStoredValue(KnownSVal V, const MemRegion *R, PathSensitiveBugReport &Report, TrackingOptions Opts={}, const StackFrameContext *Origin=nullptr)
Track how the value got stored into the given region and where it came from.
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