174 lines · cpp
1// MacOSXAPIChecker.h - Checks proper use of various MacOS X APIs --*- 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-exception6//7//===----------------------------------------------------------------------===//8//9// This defines MacOSXAPIChecker, which is an assortment of checks on calls10// to various, widely used Apple APIs.11//12// FIXME: What's currently in BasicObjCFoundationChecks.cpp should be migrated13// to here, using the new Checker interface.14//15//===----------------------------------------------------------------------===//16 17#include "clang/AST/Attr.h"18#include "clang/StaticAnalyzer/Checkers/BuiltinCheckerRegistration.h"19#include "clang/StaticAnalyzer/Core/BugReporter/BugType.h"20#include "clang/StaticAnalyzer/Core/BugReporter/CommonBugCategories.h"21#include "clang/StaticAnalyzer/Core/Checker.h"22#include "clang/StaticAnalyzer/Core/CheckerManager.h"23#include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"24#include "llvm/ADT/StringSwitch.h"25#include "llvm/Support/raw_ostream.h"26 27using namespace clang;28using namespace ento;29 30namespace {31class MacOSXAPIChecker : public Checker< check::PreStmt<CallExpr> > {32 const BugType BT_dispatchOnce{this, "Improper use of 'dispatch_once'",33 categories::AppleAPIMisuse};34 35 static const ObjCIvarRegion *getParentIvarRegion(const MemRegion *R);36 37public:38 void checkPreStmt(const CallExpr *CE, CheckerContext &C) const;39 40 void CheckDispatchOnce(CheckerContext &C, const CallExpr *CE,41 StringRef FName) const;42 43 typedef void (MacOSXAPIChecker::*SubChecker)(CheckerContext &,44 const CallExpr *,45 StringRef FName) const;46};47} //end anonymous namespace48 49//===----------------------------------------------------------------------===//50// dispatch_once and dispatch_once_f51//===----------------------------------------------------------------------===//52 53const ObjCIvarRegion *54MacOSXAPIChecker::getParentIvarRegion(const MemRegion *R) {55 const SubRegion *SR = dyn_cast<SubRegion>(R);56 while (SR) {57 if (const ObjCIvarRegion *IR = dyn_cast<ObjCIvarRegion>(SR))58 return IR;59 SR = dyn_cast<SubRegion>(SR->getSuperRegion());60 }61 return nullptr;62}63 64void MacOSXAPIChecker::CheckDispatchOnce(CheckerContext &C, const CallExpr *CE,65 StringRef FName) const {66 if (CE->getNumArgs() < 1)67 return;68 69 // Check if the first argument is improperly allocated. If so, issue a70 // warning because that's likely to be bad news.71 const MemRegion *R = C.getSVal(CE->getArg(0)).getAsRegion();72 if (!R)73 return;74 75 // Global variables are fine.76 const MemSpaceRegion *Space = R->getMemorySpace(C.getState());77 if (isa<GlobalsSpaceRegion>(Space))78 return;79 80 // Handle _dispatch_once. In some versions of the OS X SDK we have the case81 // that dispatch_once is a macro that wraps a call to _dispatch_once.82 // _dispatch_once is then a function which then calls the real dispatch_once.83 // Users do not care; they just want the warning at the top-level call.84 if (CE->getBeginLoc().isMacroID()) {85 StringRef TrimmedFName = FName.ltrim('_');86 if (TrimmedFName != FName)87 FName = TrimmedFName;88 }89 90 SmallString<256> S;91 llvm::raw_svector_ostream os(S);92 bool SuggestStatic = false;93 os << "Call to '" << FName << "' uses";94 if (const VarRegion *VR = dyn_cast<VarRegion>(R->getBaseRegion())) {95 const VarDecl *VD = VR->getDecl();96 // FIXME: These should have correct memory space and thus should be filtered97 // out earlier. This branch only fires when we're looking from a block,98 // which we analyze as a top-level declaration, onto a static local99 // in a function that contains the block.100 if (VD->isStaticLocal())101 return;102 // We filtered out globals earlier, so it must be a local variable103 // or a block variable which is under UnknownSpaceRegion.104 if (VR != R)105 os << " memory within";106 if (VD->hasAttr<BlocksAttr>())107 os << " the block variable '";108 else109 os << " the local variable '";110 os << VR->getDecl()->getName() << '\'';111 SuggestStatic = true;112 } else if (const ObjCIvarRegion *IVR = getParentIvarRegion(R)) {113 if (IVR != R)114 os << " memory within";115 os << " the instance variable '" << IVR->getDecl()->getName() << '\'';116 } else if (isa<HeapSpaceRegion>(Space)) {117 os << " heap-allocated memory";118 } else if (isa<UnknownSpaceRegion>(Space)) {119 // Presence of an IVar superregion has priority over this branch, because120 // ObjC objects are on the heap even if the core doesn't realize this.121 // Presence of a block variable base region has priority over this branch,122 // because block variables are known to be either on stack or on heap123 // (might actually move between the two, hence UnknownSpace).124 return;125 } else {126 os << " stack allocated memory";127 }128 os << " for the predicate value. Using such transient memory for "129 "the predicate is potentially dangerous.";130 if (SuggestStatic)131 os << " Perhaps you intended to declare the variable as 'static'?";132 133 ExplodedNode *N = C.generateErrorNode();134 if (!N)135 return;136 137 auto report =138 std::make_unique<PathSensitiveBugReport>(BT_dispatchOnce, os.str(), N);139 report->addRange(CE->getArg(0)->getSourceRange());140 C.emitReport(std::move(report));141}142 143//===----------------------------------------------------------------------===//144// Central dispatch function.145//===----------------------------------------------------------------------===//146 147void MacOSXAPIChecker::checkPreStmt(const CallExpr *CE,148 CheckerContext &C) const {149 StringRef Name = C.getCalleeName(CE);150 if (Name.empty())151 return;152 153 SubChecker SC =154 llvm::StringSwitch<SubChecker>(Name)155 .Cases({"dispatch_once", "_dispatch_once", "dispatch_once_f"},156 &MacOSXAPIChecker::CheckDispatchOnce)157 .Default(nullptr);158 159 if (SC)160 (this->*SC)(C, CE, Name);161}162 163//===----------------------------------------------------------------------===//164// Registration.165//===----------------------------------------------------------------------===//166 167void ento::registerMacOSXAPIChecker(CheckerManager &mgr) {168 mgr.registerChecker<MacOSXAPIChecker>();169}170 171bool ento::shouldRegisterMacOSXAPIChecker(const CheckerManager &mgr) {172 return true;173}174