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 13 #include "clang/StaticAnalyzer/Checkers/BuiltinCheckerRegistration.h" 14 #include "clang/AST/Attr.h" 15 #include "clang/StaticAnalyzer/Core/BugReporter/BugType.h" 16 #include "clang/StaticAnalyzer/Core/Checker.h" 17 #include "clang/StaticAnalyzer/Core/CheckerManager.h" 18 #include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h" 19 #include "clang/StaticAnalyzer/Core/PathSensitive/ExprEngine.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. 72 if (Optional<UndefinedVal> V = 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 = std::make_unique<PathSensitiveBugReport>(*BT, os.str(), N); 87 if (const Expr *Ex = FindBlockDeclRefExpr(BE->getBody(), VD)) 88 R->addRange(Ex->getSourceRange()); 89 bugreporter::trackStoredValue(*V, VR, *R, 90 {bugreporter::TrackingKind::Thorough, 91 /*EnableNullFPSuppression*/ false}); 92 R->disablePathPruning(); 93 // need location of block 94 C.emitReport(std::move(R)); 95 } 96 } 97 } 98 } 99 100 void ento::registerUndefCapturedBlockVarChecker(CheckerManager &mgr) { 101 mgr.registerChecker<UndefCapturedBlockVarChecker>(); 102 } 103 104 bool ento::shouldRegisterUndefCapturedBlockVarChecker(const CheckerManager &mgr) { 105 return true; 106 } 107