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 "ClangSACheckers.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 OwningPtr<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 (Stmt::const_child_iterator I = S->child_begin(), E = S->child_end();
  44        I!=E; ++I)
  45     if (const Stmt *child = *I) {
  46       const DeclRefExpr *BR = FindBlockDeclRefExpr(child, VD);
  47       if (BR)
  48         return BR;
  49     }
  50
  51   return NULL;
  52 }
  53
  54 void
  55 UndefCapturedBlockVarChecker::checkPostStmt(const BlockExpr *BE,
  56                                             CheckerContext &C) const {
  57   if (!BE->getBlockDecl()->hasCaptures())
  58     return;
  59
  60   ProgramStateRef state = C.getState();
  61   const BlockDataRegion *R =
  62     cast<BlockDataRegion>(state->getSVal(BE,
  63                                          C.getLocationContext()).getAsRegion());
  64
  65   BlockDataRegion::referenced_vars_iterator I = R->referenced_vars_begin(),
  66                                             E = R->referenced_vars_end();
  67
  68   for (; I != E; ++I) {
  69     // This VarRegion is the region associated with the block; we need
  70     // the one associated with the encompassing context.
  71     const VarRegion *VR = I.getCapturedRegion();
  72     const VarDecl *VD = VR->getDecl();
  73
  74     if (VD->getAttr<BlocksAttr>() || !VD->hasLocalStorage())
  75       continue;
  76
  77     // Get the VarRegion associated with VD in the local stack frame.
  78     if (Optional<UndefinedVal> V =
  79           state->getSVal(I.getOriginalRegion()).getAs<UndefinedVal>()) {
  80       if (ExplodedNode *N = C.generateSink()) {
  81         if (!BT)
  82           BT.reset(new BuiltinBug("uninitialized variable captured by block"));
  83
  84         // Generate a bug report.
  85         SmallString<128> buf;
  86         llvm::raw_svector_ostream os(buf);
  87
  88         os << "Variable '" << VD->getName()
  89            << "' is uninitialized when captured by block";
  90
  91         BugReport *R = new BugReport(*BT, os.str(), N);
  92         if (const Expr *Ex = FindBlockDeclRefExpr(BE->getBody(), VD))
  93           R->addRange(Ex->getSourceRange());
  94         R->addVisitor(new FindLastStoreBRVisitor(*V, VR,
  95                                              /*EnableNullFPSuppression*/false));
  96         R->disablePathPruning();
  97         // need location of block
  98         C.emitReport(R);
  99       }
 100     }
 101   }
 102 }
 103
 104 void ento::registerUndefCapturedBlockVarChecker(CheckerManager &mgr) {
 105   mgr.registerChecker<UndefCapturedBlockVarChecker>();
 106 }