clang  9.0.0
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 
23 using namespace clang;
24 using namespace ento;
25 
26 namespace {
27 class UndefCapturedBlockVarChecker
28  : public Checker< check::PostStmt<BlockExpr> > {
29  mutable std::unique_ptr<BugType> BT;
30 
31 public:
32  void checkPostStmt(const BlockExpr *BE, CheckerContext &C) const;
33 };
34 } // end anonymous namespace
35 
36 static const DeclRefExpr *FindBlockDeclRefExpr(const Stmt *S,
37  const VarDecl *VD) {
38  if (const DeclRefExpr *BR = dyn_cast<DeclRefExpr>(S))
39  if (BR->getDecl() == VD)
40  return BR;
41 
42  for (const Stmt *Child : S->children())
43  if (Child)
44  if (const DeclRefExpr *BR = FindBlockDeclRefExpr(Child, VD))
45  return BR;
46 
47  return nullptr;
48 }
49 
50 void
51 UndefCapturedBlockVarChecker::checkPostStmt(const BlockExpr *BE,
52  CheckerContext &C) const {
53  if (!BE->getBlockDecl()->hasCaptures())
54  return;
55 
56  ProgramStateRef state = C.getState();
57  auto *R = cast<BlockDataRegion>(C.getSVal(BE).getAsRegion());
58 
59  BlockDataRegion::referenced_vars_iterator I = R->referenced_vars_begin(),
60  E = R->referenced_vars_end();
61 
62  for (; I != E; ++I) {
63  // This VarRegion is the region associated with the block; we need
64  // the one associated with the encompassing context.
65  const VarRegion *VR = I.getCapturedRegion();
66  const VarDecl *VD = VR->getDecl();
67 
68  if (VD->hasAttr<BlocksAttr>() || !VD->hasLocalStorage())
69  continue;
70 
71  // Get the VarRegion associated with VD in the local stack frame.
73  state->getSVal(I.getOriginalRegion()).getAs<UndefinedVal>()) {
74  if (ExplodedNode *N = C.generateErrorNode()) {
75  if (!BT)
76  BT.reset(
77  new BuiltinBug(this, "uninitialized variable captured by block"));
78 
79  // Generate a bug report.
80  SmallString<128> buf;
81  llvm::raw_svector_ostream os(buf);
82 
83  os << "Variable '" << VD->getName()
84  << "' is uninitialized when captured by block";
85 
86  auto R = llvm::make_unique<BugReport>(*BT, os.str(), N);
87  if (const Expr *Ex = FindBlockDeclRefExpr(BE->getBody(), VD))
88  R->addRange(Ex->getSourceRange());
89  R->addVisitor(llvm::make_unique<FindLastStoreBRVisitor>(
90  *V, VR, /*EnableNullFPSuppression*/ false));
91  R->disablePathPruning();
92  // need location of block
93  C.emitReport(std::move(R));
94  }
95  }
96  }
97 }
98 
99 void ento::registerUndefCapturedBlockVarChecker(CheckerManager &mgr) {
100  mgr.registerChecker<UndefCapturedBlockVarChecker>();
101 }
102 
103 bool ento::shouldRegisterUndefCapturedBlockVarChecker(const LangOptions &LO) {
104  return true;
105 }
const BlockDecl * getBlockDecl() const
Definition: Expr.h:5555
bool hasCaptures() const
True if this block (or its nested blocks) captures anything of local storage from its enclosing scope...
Definition: Decl.h:4034
static const DeclRefExpr * FindBlockDeclRefExpr(const Stmt *S, const VarDecl *VD)
Stmt - This represents one statement.
Definition: Stmt.h:66
IntrusiveRefCntPtr< const ProgramState > ProgramStateRef
Represents a variable declaration or definition.
Definition: Decl.h:812
Keeps track of the various options that can be enabled, which controls the dialect of C or C++ that i...
Definition: LangOptions.h:49
i32 captured_struct **param SharedsTy A type which contains references the shared variables *param Shareds Context with the list of shared variables from the p *TaskFunction *param Data Additional data for task generation like final * state
child_range children()
Definition: Stmt.cpp:212
const Stmt * getBody() const
Definition: Expr.cpp:2361
bool hasAttr() const
Definition: DeclBase.h:542
This represents one expression.
Definition: Expr.h:108
bool hasLocalStorage() const
Returns true if a variable with function scope is a non-static local variable.
Definition: Decl.h:1035
#define V(N, I)
Definition: ASTContext.h:2907
BlockExpr - Adaptor class for mixing a BlockDecl with expressions.
Definition: Expr.h:5541
Dataflow Directional Tag Classes.
StringRef getName() const
Get the name of identifier for this declaration as a StringRef.
Definition: Decl.h:275
A reference to a declared variable, function, enum, etc.
Definition: Expr.h:1141