1 // UndefCapturedBlockVarChecker.cpp - Uninitialized captured vars -*- C++ -*-=//
2 //
3 // The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // This checker detects blocks that capture uninitialized values.
11 //
12 //===----------------------------------------------------------------------===//
13
14 #include "ClangSACheckers.h"
15 #include "clang/AST/Attr.h"
16 #include "clang/StaticAnalyzer/Core/BugReporter/BugType.h"
17 #include "clang/StaticAnalyzer/Core/Checker.h"
18 #include "clang/StaticAnalyzer/Core/CheckerManager.h"
19 #include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
20 #include "clang/StaticAnalyzer/Core/PathSensitive/ExprEngine.h"
21 #include "llvm/ADT/SmallString.h"
22 #include "llvm/Support/raw_ostream.h"
23
24 using namespace clang;
25 using namespace ento;
26
27 namespace {
28 class UndefCapturedBlockVarChecker
29 : public Checker< check::PostStmt<BlockExpr> > {
30 mutable std::unique_ptr<BugType> BT;
31
32 public:
33 void checkPostStmt(const BlockExpr *BE, CheckerContext &C) const;
34 };
35 } // end anonymous namespace
36
FindBlockDeclRefExpr(const Stmt * S,const VarDecl * VD)37 static 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
51 void
checkPostStmt(const BlockExpr * BE,CheckerContext & C) const52 UndefCapturedBlockVarChecker::checkPostStmt(const BlockExpr *BE,
53 CheckerContext &C) const {
54 if (!BE->getBlockDecl()->hasCaptures())
55 return;
56
57 ProgramStateRef state = C.getState();
58 const BlockDataRegion *R =
59 cast<BlockDataRegion>(state->getSVal(BE,
60 C.getLocationContext()).getAsRegion());
61
62 BlockDataRegion::referenced_vars_iterator I = R->referenced_vars_begin(),
63 E = R->referenced_vars_end();
64
65 for (; I != E; ++I) {
66 // This VarRegion is the region associated with the block; we need
67 // the one associated with the encompassing context.
68 const VarRegion *VR = I.getCapturedRegion();
69 const VarDecl *VD = VR->getDecl();
70
71 if (VD->hasAttr<BlocksAttr>() || !VD->hasLocalStorage())
72 continue;
73
74 // Get the VarRegion associated with VD in the local stack frame.
75 if (Optional<UndefinedVal> V =
76 state->getSVal(I.getOriginalRegion()).getAs<UndefinedVal>()) {
77 if (ExplodedNode *N = C.generateErrorNode()) {
78 if (!BT)
79 BT.reset(
80 new BuiltinBug(this, "uninitialized variable captured by block"));
81
82 // Generate a bug report.
83 SmallString<128> buf;
84 llvm::raw_svector_ostream os(buf);
85
86 os << "Variable '" << VD->getName()
87 << "' is uninitialized when captured by block";
88
89 auto R = llvm::make_unique<BugReport>(*BT, os.str(), N);
90 if (const Expr *Ex = FindBlockDeclRefExpr(BE->getBody(), VD))
91 R->addRange(Ex->getSourceRange());
92 R->addVisitor(llvm::make_unique<FindLastStoreBRVisitor>(
93 *V, VR, /*EnableNullFPSuppression*/ false));
94 R->disablePathPruning();
95 // need location of block
96 C.emitReport(std::move(R));
97 }
98 }
99 }
100 }
101
registerUndefCapturedBlockVarChecker(CheckerManager & mgr)102 void ento::registerUndefCapturedBlockVarChecker(CheckerManager &mgr) {
103 mgr.registerChecker<UndefCapturedBlockVarChecker>();
104 }
105