1 //===--- UndefinedArraySubscriptChecker.h ----------------------*- 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 defines UndefinedArraySubscriptChecker, a builtin check in ExprEngine
11 // that performs checks for undefined array subscripts.
12 //
13 //===----------------------------------------------------------------------===//
14 
15 #include "ClangSACheckers.h"
16 #include "clang/AST/DeclCXX.h"
17 #include "clang/StaticAnalyzer/Core/BugReporter/BugType.h"
18 #include "clang/StaticAnalyzer/Core/Checker.h"
19 #include "clang/StaticAnalyzer/Core/CheckerManager.h"
20 #include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
21 
22 using namespace clang;
23 using namespace ento;
24 
25 namespace {
26 class UndefinedArraySubscriptChecker
27   : public Checker< check::PreStmt<ArraySubscriptExpr> > {
28   mutable std::unique_ptr<BugType> BT;
29 
30 public:
31   void checkPreStmt(const ArraySubscriptExpr *A, CheckerContext &C) const;
32 };
33 } // end anonymous namespace
34 
35 void
checkPreStmt(const ArraySubscriptExpr * A,CheckerContext & C) const36 UndefinedArraySubscriptChecker::checkPreStmt(const ArraySubscriptExpr *A,
37                                              CheckerContext &C) const {
38   const Expr *Index = A->getIdx();
39   if (!C.getSVal(Index).isUndef())
40     return;
41 
42   // Sema generates anonymous array variables for copying array struct fields.
43   // Don't warn if we're in an implicitly-generated constructor.
44   const Decl *D = C.getLocationContext()->getDecl();
45   if (const CXXConstructorDecl *Ctor = dyn_cast<CXXConstructorDecl>(D))
46     if (Ctor->isDefaulted())
47       return;
48 
49   ExplodedNode *N = C.generateSink();
50   if (!N)
51     return;
52   if (!BT)
53     BT.reset(new BuiltinBug(this, "Array subscript is undefined"));
54 
55   // Generate a report for this bug.
56   BugReport *R = new BugReport(*BT, BT->getName(), N);
57   R->addRange(A->getIdx()->getSourceRange());
58   bugreporter::trackNullOrUndefValue(N, A->getIdx(), *R);
59   C.emitReport(R);
60 }
61 
registerUndefinedArraySubscriptChecker(CheckerManager & mgr)62 void ento::registerUndefinedArraySubscriptChecker(CheckerManager &mgr) {
63   mgr.registerChecker<UndefinedArraySubscriptChecker>();
64 }
65