clang 19.0.0git
UndefCapturedBlockVarChecker.cpp
Go to the documentation of this file.
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 const BugType BT{this, "uninitialized variable captured by block"};
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 for (auto Var : R->referenced_vars()) {
61 // This VarRegion is the region associated with the block; we need
62 // the one associated with the encompassing context.
63 const VarRegion *VR = Var.getCapturedRegion();
64 const VarDecl *VD = VR->getDecl();
65
66 if (VD->hasAttr<BlocksAttr>() || !VD->hasLocalStorage())
67 continue;
68
69 // Get the VarRegion associated with VD in the local stack frame.
70 if (std::optional<UndefinedVal> V =
71 state->getSVal(Var.getOriginalRegion()).getAs<UndefinedVal>()) {
72 if (ExplodedNode *N = C.generateErrorNode()) {
73 // Generate a bug report.
75 llvm::raw_svector_ostream os(buf);
76
77 os << "Variable '" << VD->getName()
78 << "' is uninitialized when captured by block";
79
80 auto R = std::make_unique<PathSensitiveBugReport>(BT, os.str(), N);
81 if (const Expr *Ex = FindBlockDeclRefExpr(BE->getBody(), VD))
82 R->addRange(Ex->getSourceRange());
84 {bugreporter::TrackingKind::Thorough,
85 /*EnableNullFPSuppression*/ false});
86 R->disablePathPruning();
87 // need location of block
88 C.emitReport(std::move(R));
89 }
90 }
91 }
92}
93
94void ento::registerUndefCapturedBlockVarChecker(CheckerManager &mgr) {
95 mgr.registerChecker<UndefCapturedBlockVarChecker>();
96}
97
98bool ento::shouldRegisterUndefCapturedBlockVarChecker(const CheckerManager &mgr) {
99 return true;
100}
#define V(N, I)
Definition: ASTContext.h:3300
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:4615
BlockExpr - Adaptor class for mixing a BlockDecl with expressions.
Definition: Expr.h:6331
const Stmt * getBody() const
Definition: Expr.cpp:2522
const BlockDecl * getBlockDecl() const
Definition: Expr.h:6343
A reference to a declared variable, function, enum, etc.
Definition: Expr.h:1260
bool hasAttr() const
Definition: DeclBase.h:583
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:276
Stmt - This represents one statement.
Definition: Stmt.h:84
Represents a variable declaration or definition.
Definition: Decl.h:918
bool hasLocalStorage() const
Returns true if a variable with function scope is a non-static local variable.
Definition: Decl.h:1171
CHECKER * registerChecker(AT &&... Args)
Used to register checkers.
const VarDecl * getDecl() const override=0
void trackStoredValue(SVal 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.
The JSON file list parser is used to communicate input to InstallAPI.