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1 //== ReturnUndefChecker.cpp -------------------------------------*- 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 file defines ReturnUndefChecker, which is a path-sensitive
11 // check which looks for undefined or garbage values being returned to the
12 // caller.
13 //
14 //===----------------------------------------------------------------------===//
15 
16 #include "ClangSACheckers.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/BugReporter/BugType.h"
21 
22 using namespace clang;
23 using namespace ento;
24 
25 namespace {
26 class ReturnUndefChecker :
27     public Checker< check::PreStmt<ReturnStmt> > {
28   mutable llvm::OwningPtr<BuiltinBug> BT;
29 public:
30   void checkPreStmt(const ReturnStmt *RS, CheckerContext &C) const;
31 };
32 }
33 
checkPreStmt(const ReturnStmt * RS,CheckerContext & C) const34 void ReturnUndefChecker::checkPreStmt(const ReturnStmt *RS,
35                                       CheckerContext &C) const {
36 
37   const Expr *RetE = RS->getRetValue();
38   if (!RetE)
39     return;
40 
41   if (!C.getState()->getSVal(RetE).isUndef())
42     return;
43 
44   ExplodedNode *N = C.generateSink();
45 
46   if (!N)
47     return;
48 
49   if (!BT)
50     BT.reset(new BuiltinBug("Garbage return value",
51                             "Undefined or garbage value returned to caller"));
52 
53   EnhancedBugReport *report =
54     new EnhancedBugReport(*BT, BT->getDescription(), N);
55 
56   report->addRange(RetE->getSourceRange());
57   report->addVisitorCreator(bugreporter::registerTrackNullOrUndefValue, RetE);
58 
59   C.EmitReport(report);
60 }
61 
registerReturnUndefChecker(CheckerManager & mgr)62 void ento::registerReturnUndefChecker(CheckerManager &mgr) {
63   mgr.registerChecker<ReturnUndefChecker>();
64 }
65