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 #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   BlockDataRegion::referenced_vars_iterator I = R->referenced_vars_begin(),
  61                                             E = R->referenced_vars_end();
  62
  63   for (; I != E; ++I) {
  64     // This VarRegion is the region associated with the block; we need
  65     // the one associated with the encompassing context.
  66     const VarRegion *VR = I.getCapturedRegion();
  67     const VarDecl *VD = VR->getDecl();
  68
  69     if (VD->hasAttr<BlocksAttr>() || !VD->hasLocalStorage())
  70       continue;
  71
  72     // Get the VarRegion associated with VD in the local stack frame.
  73     if (std::optional<UndefinedVal> V =
  74             state->getSVal(I.getOriginalRegion()).getAs<UndefinedVal>()) {
  75       if (ExplodedNode *N = C.generateErrorNode()) {
  76         if (!BT)
  77           BT.reset(
  78               new BuiltinBug(this, "uninitialized variable captured by block"));
  79
  80         // Generate a bug report.
  81         SmallString<128> buf;
  82         llvm::raw_svector_ostream os(buf);
  83
  84         os << "Variable '" << VD->getName()
  85            << "' is uninitialized when captured by block";
  86
  87         auto R = std::make_unique<PathSensitiveBugReport>(*BT, os.str(), N);
  88         if (const Expr *Ex = FindBlockDeclRefExpr(BE->getBody(), VD))
  89           R->addRange(Ex->getSourceRange());
  90         bugreporter::trackStoredValue(*V, VR, *R,
  91                                       {bugreporter::TrackingKind::Thorough,
  92                                        /*EnableNullFPSuppression*/ false});
  93         R->disablePathPruning();
  94         // need location of block
  95         C.emitReport(std::move(R));
  96       }
  97     }
  98   }
  99 }
 100
 101 void ento::registerUndefCapturedBlockVarChecker(CheckerManager &mgr) {
 102   mgr.registerChecker<UndefCapturedBlockVarChecker>();
 103 }
 104
 105 bool ento::shouldRegisterUndefCapturedBlockVarChecker(const CheckerManager &mgr) {
 106   return true;
 107 }