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/StaticAnalyzer/Core/Checker.h"
16 #include "clang/StaticAnalyzer/Core/CheckerManager.h"
17 #include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
18 #include "clang/StaticAnalyzer/Core/PathSensitive/ExprEngine.h"
19 #include "clang/StaticAnalyzer/Core/BugReporter/BugType.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 OwningPtr<BugType> BT;
30
31 public:
32 void checkPostStmt(const BlockExpr *BE, CheckerContext &C) const;
33 };
34 } // end anonymous namespace
35
FindBlockDeclRefExpr(const Stmt * S,const VarDecl * VD)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 (Stmt::const_child_iterator I = S->child_begin(), E = S->child_end();
43 I!=E; ++I)
44 if (const Stmt *child = *I) {
45 const DeclRefExpr *BR = FindBlockDeclRefExpr(child, VD);
46 if (BR)
47 return BR;
48 }
49
50 return NULL;
51 }
52
53 void
checkPostStmt(const BlockExpr * BE,CheckerContext & C) const54 UndefCapturedBlockVarChecker::checkPostStmt(const BlockExpr *BE,
55 CheckerContext &C) const {
56 if (!BE->getBlockDecl()->hasCaptures())
57 return;
58
59 ProgramStateRef state = C.getState();
60 const BlockDataRegion *R =
61 cast<BlockDataRegion>(state->getSVal(BE,
62 C.getLocationContext()).getAsRegion());
63
64 BlockDataRegion::referenced_vars_iterator I = R->referenced_vars_begin(),
65 E = R->referenced_vars_end();
66
67 for (; I != E; ++I) {
68 // This VarRegion is the region associated with the block; we need
69 // the one associated with the encompassing context.
70 const VarRegion *VR = *I;
71 const VarDecl *VD = VR->getDecl();
72
73 if (VD->getAttr<BlocksAttr>() || !VD->hasLocalStorage())
74 continue;
75
76 // Get the VarRegion associated with VD in the local stack frame.
77 const LocationContext *LC = C.getLocationContext();
78 VR = C.getSValBuilder().getRegionManager().getVarRegion(VD, LC);
79 SVal VRVal = state->getSVal(VR);
80
81 if (VRVal.isUndef())
82 if (ExplodedNode *N = C.generateSink()) {
83 if (!BT)
84 BT.reset(new BuiltinBug("uninitialized variable captured by block"));
85
86 // Generate a bug report.
87 SmallString<128> buf;
88 llvm::raw_svector_ostream os(buf);
89
90 os << "Variable '" << VD->getName()
91 << "' is uninitialized when captured by block";
92
93 BugReport *R = new BugReport(*BT, os.str(), N);
94 if (const Expr *Ex = FindBlockDeclRefExpr(BE->getBody(), VD))
95 R->addRange(Ex->getSourceRange());
96 R->addVisitor(new FindLastStoreBRVisitor(VRVal, VR));
97 R->disablePathPruning();
98 // need location of block
99 C.EmitReport(R);
100 }
101 }
102 }
103
registerUndefCapturedBlockVarChecker(CheckerManager & mgr)104 void ento::registerUndefCapturedBlockVarChecker(CheckerManager &mgr) {
105 mgr.registerChecker<UndefCapturedBlockVarChecker>();
106 }
107