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 "AllocationState.h" 16 #include "clang/StaticAnalyzer/Checkers/BuiltinCheckerRegistration.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/CallDescription.h" 21 #include "clang/StaticAnalyzer/Core/PathSensitive/CallEvent.h" 22 #include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h" 23 #include "clang/StaticAnalyzer/Core/PathSensitive/MemRegion.h" 24 25 using namespace clang; 26 using namespace ento; 27 28 namespace { 29 class PutenvStackArrayChecker : public Checker<check::PostCall> { 30 private: 31 BugType BT{this, "'putenv' called with stack-allocated string", 32 categories::SecurityError}; 33 const CallDescription Putenv{CDM::CLibrary, {"putenv"}, 1}; 34 35 public: 36 void checkPostCall(const CallEvent &Call, CheckerContext &C) const; 37 }; 38 } // namespace 39 40 void PutenvStackArrayChecker::checkPostCall(const CallEvent &Call, 41 CheckerContext &C) const { 42 if (!Putenv.matches(Call)) 43 return; 44 45 SVal ArgV = Call.getArgSVal(0); 46 const Expr *ArgExpr = Call.getArgExpr(0); 47 48 const auto *SSR = 49 dyn_cast<StackSpaceRegion>(ArgV.getAsRegion()->getMemorySpace()); 50 if (!SSR) 51 return; 52 const auto *StackFrameFuncD = 53 dyn_cast_or_null<FunctionDecl>(SSR->getStackFrame()->getDecl()); 54 if (StackFrameFuncD && StackFrameFuncD->isMain()) 55 return; 56 57 StringRef ErrorMsg = "The 'putenv' function should not be called with " 58 "arrays that have automatic storage"; 59 ExplodedNode *N = C.generateErrorNode(); 60 auto Report = std::make_unique<PathSensitiveBugReport>(BT, ErrorMsg, N); 61 62 // Track the argument. 63 bugreporter::trackExpressionValue(Report->getErrorNode(), ArgExpr, *Report); 64 65 C.emitReport(std::move(Report)); 66 } 67 68 void ento::registerPutenvStackArray(CheckerManager &Mgr) { 69 Mgr.registerChecker<PutenvStackArrayChecker>(); 70 } 71 72 bool ento::shouldRegisterPutenvStackArray(const CheckerManager &) { 73 return true; 74 } 75