1 //== PutenvStackArrayChecker.cpp ------------------------------- -*- 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 file defines PutenvStackArrayChecker which finds calls of ``putenv``
10 // function with automatic array variable as the argument.
11 // https://wiki.sei.cmu.edu/confluence/x/6NYxBQ
12 //
13 //===----------------------------------------------------------------------===//
14
15 #include "clang/StaticAnalyzer/Checkers/BuiltinCheckerRegistration.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/CallDescription.h"
20 #include "clang/StaticAnalyzer/Core/PathSensitive/CallEvent.h"
21 #include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
22 #include "clang/StaticAnalyzer/Core/PathSensitive/MemRegion.h"
23
24 using namespace clang;
25 using namespace ento;
26
27 namespace {
28 class PutenvStackArrayChecker : public Checker<check::PostCall> {
29 private:
30 BugType BT{this, "'putenv' called with stack-allocated string",
31 categories::SecurityError};
32 const CallDescription Putenv{CDM::CLibrary, {"putenv"}, 1};
33
34 public:
35 void checkPostCall(const CallEvent &Call, CheckerContext &C) const;
36 };
37 } // namespace
38
checkPostCall(const CallEvent & Call,CheckerContext & C) const39 void PutenvStackArrayChecker::checkPostCall(const CallEvent &Call,
40 CheckerContext &C) const {
41 if (!Putenv.matches(Call))
42 return;
43
44 SVal ArgV = Call.getArgSVal(0);
45 const Expr *ArgExpr = Call.getArgExpr(0);
46
47 if (!ArgV.getAsRegion())
48 return;
49
50 const auto *SSR =
51 ArgV.getAsRegion()->getMemorySpaceAs<StackSpaceRegion>(C.getState());
52 if (!SSR)
53 return;
54 const auto *StackFrameFuncD =
55 dyn_cast_or_null<FunctionDecl>(SSR->getStackFrame()->getDecl());
56 if (StackFrameFuncD && StackFrameFuncD->isMain())
57 return;
58
59 StringRef ErrorMsg = "The 'putenv' function should not be called with "
60 "arrays that have automatic storage";
61 ExplodedNode *N = C.generateErrorNode();
62 auto Report = std::make_unique<PathSensitiveBugReport>(BT, ErrorMsg, N);
63
64 // Track the argument.
65 bugreporter::trackExpressionValue(Report->getErrorNode(), ArgExpr, *Report);
66
67 C.emitReport(std::move(Report));
68 }
69
registerPutenvStackArray(CheckerManager & Mgr)70 void ento::registerPutenvStackArray(CheckerManager &Mgr) {
71 Mgr.registerChecker<PutenvStackArrayChecker>();
72 }
73
shouldRegisterPutenvStackArray(const CheckerManager &)74 bool ento::shouldRegisterPutenvStackArray(const CheckerManager &) {
75 return true;
76 }
77