contrib/llvm/tools/clang/lib/StaticAnalyzer/Checkers/UndefCapturedBlockVarChecker.cpp

   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 "clang/StaticAnalyzer/Checkers/BuiltinCheckerRegistration.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 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 (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 = llvm::make_unique<BugReport>(*BT, os.str(), N);
  88         if (const Expr *Ex = FindBlockDeclRefExpr(BE->getBody(), VD))
  89           R->addRange(Ex->getSourceRange());
  90         R->addVisitor(llvm::make_unique<FindLastStoreBRVisitor>(
  91             *V, VR, /*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 }