contrib/llvm-project/clang/lib/StaticAnalyzer/Checkers/UndefCapturedBlockVarChecker.cpp

   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 = llvm::make_unique<BugReport>(*BT, os.str(), N);
  87         if (const Expr *Ex = FindBlockDeclRefExpr(BE->getBody(), VD))
  88           R->addRange(Ex->getSourceRange());
  89         R->addVisitor(llvm::make_unique<FindLastStoreBRVisitor>(
  90             *V, VR, /*EnableNullFPSuppression*/ false));
  91         R->disablePathPruning();
  92         // need location of block
  93         C.emitReport(std::move(R));
  94       }
  95     }
  96   }
  97 }
  98
  99 void ento::registerUndefCapturedBlockVarChecker(CheckerManager &mgr) {
 100   mgr.registerChecker<UndefCapturedBlockVarChecker>();
 101 }
 102
 103 bool ento::shouldRegisterUndefCapturedBlockVarChecker(const LangOptions &LO) {
 104   return true;
 105 }