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 OwningPtr<BugType> BT; 31 32 public: 33 void checkPostStmt(const BlockExpr *BE, CheckerContext &C) const; 34 }; 35 } // end anonymous namespace 36 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 (Stmt::const_child_iterator I = S->child_begin(), E = S->child_end(); 44 I!=E; ++I) 45 if (const Stmt *child = *I) { 46 const DeclRefExpr *BR = FindBlockDeclRefExpr(child, VD); 47 if (BR) 48 return BR; 49 } 50 51 return NULL; 52 } 53 54 void 55 UndefCapturedBlockVarChecker::checkPostStmt(const BlockExpr *BE, 56 CheckerContext &C) const { 57 if (!BE->getBlockDecl()->hasCaptures()) 58 return; 59 60 ProgramStateRef state = C.getState(); 61 const BlockDataRegion *R = 62 cast<BlockDataRegion>(state->getSVal(BE, 63 C.getLocationContext()).getAsRegion()); 64 65 BlockDataRegion::referenced_vars_iterator I = R->referenced_vars_begin(), 66 E = R->referenced_vars_end(); 67 68 for (; I != E; ++I) { 69 // This VarRegion is the region associated with the block; we need 70 // the one associated with the encompassing context. 71 const VarRegion *VR = I.getCapturedRegion(); 72 const VarDecl *VD = VR->getDecl(); 73 74 if (VD->getAttr<BlocksAttr>() || !VD->hasLocalStorage()) 75 continue; 76 77 // Get the VarRegion associated with VD in the local stack frame. 78 SVal VRVal = state->getSVal(I.getOriginalRegion()); 79 80 if (VRVal.isUndef()) 81 if (ExplodedNode *N = C.generateSink()) { 82 if (!BT) 83 BT.reset(new BuiltinBug("uninitialized variable captured by block")); 84 85 // Generate a bug report. 86 SmallString<128> buf; 87 llvm::raw_svector_ostream os(buf); 88 89 os << "Variable '" << VD->getName() 90 << "' is uninitialized when captured by block"; 91 92 BugReport *R = new BugReport(*BT, os.str(), N); 93 if (const Expr *Ex = FindBlockDeclRefExpr(BE->getBody(), VD)) 94 R->addRange(Ex->getSourceRange()); 95 R->addVisitor(new FindLastStoreBRVisitor(VRVal, VR)); 96 R->disablePathPruning(); 97 // need location of block 98 C.emitReport(R); 99 } 100 } 101 } 102 103 void ento::registerUndefCapturedBlockVarChecker(CheckerManager &mgr) { 104 mgr.registerChecker<UndefCapturedBlockVarChecker>(); 105 } 106