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 39 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 70 void ento::registerPutenvStackArray(CheckerManager &Mgr) { 71 Mgr.registerChecker<PutenvStackArrayChecker>(); 72 } 73 74 bool ento::shouldRegisterPutenvStackArray(const CheckerManager &) { 75 return true; 76 } 77