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 #include <optional> 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 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 52 UndefCapturedBlockVarChecker::checkPostStmt(const BlockExpr *BE, 53 CheckerContext &C) const { 54 if (!BE->getBlockDecl()->hasCaptures()) 55 return; 56 57 ProgramStateRef state = C.getState(); 58 auto *R = cast<BlockDataRegion>(C.getSVal(BE).getAsRegion()); 59 60 for (auto Var : R->referenced_vars()) { 61 // This VarRegion is the region associated with the block; we need 62 // the one associated with the encompassing context. 63 const VarRegion *VR = Var.getCapturedRegion(); 64 const VarDecl *VD = VR->getDecl(); 65 66 if (VD->hasAttr<BlocksAttr>() || !VD->hasLocalStorage()) 67 continue; 68 69 // Get the VarRegion associated with VD in the local stack frame. 70 if (std::optional<UndefinedVal> V = 71 state->getSVal(Var.getOriginalRegion()).getAs<UndefinedVal>()) { 72 if (ExplodedNode *N = C.generateErrorNode()) { 73 if (!BT) 74 BT.reset( 75 new BuiltinBug(this, "uninitialized variable captured by block")); 76 77 // Generate a bug report. 78 SmallString<128> buf; 79 llvm::raw_svector_ostream os(buf); 80 81 os << "Variable '" << VD->getName() 82 << "' is uninitialized when captured by block"; 83 84 auto R = std::make_unique<PathSensitiveBugReport>(*BT, os.str(), N); 85 if (const Expr *Ex = FindBlockDeclRefExpr(BE->getBody(), VD)) 86 R->addRange(Ex->getSourceRange()); 87 bugreporter::trackStoredValue(*V, VR, *R, 88 {bugreporter::TrackingKind::Thorough, 89 /*EnableNullFPSuppression*/ false}); 90 R->disablePathPruning(); 91 // need location of block 92 C.emitReport(std::move(R)); 93 } 94 } 95 } 96 } 97 98 void ento::registerUndefCapturedBlockVarChecker(CheckerManager &mgr) { 99 mgr.registerChecker<UndefCapturedBlockVarChecker>(); 100 } 101 102 bool ento::shouldRegisterUndefCapturedBlockVarChecker(const CheckerManager &mgr) { 103 return true; 104 } 105