1 //== ObjCContainersChecker.cpp - Path sensitive checker for CFArray *- C++ -*=//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // Performs path sensitive checks of Core Foundation static containers like
12 // 1) Check for buffer overflows:
13 // In CFArrayGetArrayAtIndex( myArray, index), if the index is outside the
14 // index space of theArray (0 to N-1 inclusive (where N is the count of
15 // theArray), the behavior is undefined.
17 //===----------------------------------------------------------------------===//
19 #include "clang/StaticAnalyzer/Checkers/BuiltinCheckerRegistration.h"
20 #include "clang/AST/ParentMap.h"
21 #include "clang/StaticAnalyzer/Core/BugReporter/BugType.h"
22 #include "clang/StaticAnalyzer/Core/Checker.h"
23 #include "clang/StaticAnalyzer/Core/CheckerManager.h"
24 #include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
25 #include "clang/StaticAnalyzer/Core/PathSensitive/ProgramStateTrait.h"
27 using namespace clang;
31 class ObjCContainersChecker : public Checker< check::PreStmt<CallExpr>,
32 check::PostStmt<CallExpr>,
33 check::PointerEscape> {
34 mutable std::unique_ptr<BugType> BT;
35 inline void initBugType() const {
37 BT.reset(new BugType(this, "CFArray API",
38 categories::CoreFoundationObjectiveC));
41 inline SymbolRef getArraySym(const Expr *E, CheckerContext &C) const {
42 SVal ArrayRef = C.getSVal(E);
43 SymbolRef ArraySym = ArrayRef.getAsSymbol();
47 void addSizeInfo(const Expr *Array, const Expr *Size,
48 CheckerContext &C) const;
51 /// A tag to id this checker.
52 static void *getTag() { static int Tag; return &Tag; }
54 void checkPostStmt(const CallExpr *CE, CheckerContext &C) const;
55 void checkPreStmt(const CallExpr *CE, CheckerContext &C) const;
56 ProgramStateRef checkPointerEscape(ProgramStateRef State,
57 const InvalidatedSymbols &Escaped,
58 const CallEvent *Call,
59 PointerEscapeKind Kind) const;
61 void printState(raw_ostream &OS, ProgramStateRef State,
62 const char *NL, const char *Sep) const;
64 } // end anonymous namespace
66 // ProgramState trait - a map from array symbol to its state.
67 REGISTER_MAP_WITH_PROGRAMSTATE(ArraySizeMap, SymbolRef, DefinedSVal)
69 void ObjCContainersChecker::addSizeInfo(const Expr *Array, const Expr *Size,
70 CheckerContext &C) const {
71 ProgramStateRef State = C.getState();
72 SVal SizeV = C.getSVal(Size);
73 // Undefined is reported by another checker.
74 if (SizeV.isUnknownOrUndef())
77 // Get the ArrayRef symbol.
78 SVal ArrayRef = C.getSVal(Array);
79 SymbolRef ArraySym = ArrayRef.getAsSymbol();
84 State->set<ArraySizeMap>(ArraySym, SizeV.castAs<DefinedSVal>()));
87 void ObjCContainersChecker::checkPostStmt(const CallExpr *CE,
88 CheckerContext &C) const {
89 StringRef Name = C.getCalleeName(CE);
90 if (Name.empty() || CE->getNumArgs() < 1)
93 // Add array size information to the state.
94 if (Name.equals("CFArrayCreate")) {
95 if (CE->getNumArgs() < 3)
97 // Note, we can visit the Create method in the post-visit because
98 // the CFIndex parameter is passed in by value and will not be invalidated
100 addSizeInfo(CE, CE->getArg(2), C);
104 if (Name.equals("CFArrayGetCount")) {
105 addSizeInfo(CE->getArg(0), CE, C);
110 void ObjCContainersChecker::checkPreStmt(const CallExpr *CE,
111 CheckerContext &C) const {
112 StringRef Name = C.getCalleeName(CE);
113 if (Name.empty() || CE->getNumArgs() < 2)
116 // Check the array access.
117 if (Name.equals("CFArrayGetValueAtIndex")) {
118 ProgramStateRef State = C.getState();
119 // Retrieve the size.
120 // Find out if we saw this array symbol before and have information about
122 const Expr *ArrayExpr = CE->getArg(0);
123 SymbolRef ArraySym = getArraySym(ArrayExpr, C);
127 const DefinedSVal *Size = State->get<ArraySizeMap>(ArraySym);
133 const Expr *IdxExpr = CE->getArg(1);
134 SVal IdxVal = C.getSVal(IdxExpr);
135 if (IdxVal.isUnknownOrUndef())
137 DefinedSVal Idx = IdxVal.castAs<DefinedSVal>();
139 // Now, check if 'Idx in [0, Size-1]'.
140 const QualType T = IdxExpr->getType();
141 ProgramStateRef StInBound = State->assumeInBound(Idx, *Size, true, T);
142 ProgramStateRef StOutBound = State->assumeInBound(Idx, *Size, false, T);
143 if (StOutBound && !StInBound) {
144 ExplodedNode *N = C.generateErrorNode(StOutBound);
148 auto R = llvm::make_unique<BugReport>(*BT, "Index is out of bounds", N);
149 R->addRange(IdxExpr->getSourceRange());
150 bugreporter::trackExpressionValue(N, IdxExpr, *R,
151 /*EnableNullFPSuppression=*/false);
152 C.emitReport(std::move(R));
159 ObjCContainersChecker::checkPointerEscape(ProgramStateRef State,
160 const InvalidatedSymbols &Escaped,
161 const CallEvent *Call,
162 PointerEscapeKind Kind) const {
163 for (const auto &Sym : Escaped) {
164 // When a symbol for a mutable array escapes, we can't reason precisely
165 // about its size any more -- so remove it from the map.
166 // Note that we aren't notified here when a CFMutableArrayRef escapes as a
167 // CFArrayRef. This is because CFArrayRef is typedef'd as a pointer to a
168 // const-qualified type.
169 State = State->remove<ArraySizeMap>(Sym);
174 void ObjCContainersChecker::printState(raw_ostream &OS, ProgramStateRef State,
175 const char *NL, const char *Sep) const {
176 ArraySizeMapTy Map = State->get<ArraySizeMap>();
180 OS << Sep << "ObjC container sizes :" << NL;
182 OS << I.first << " : " << I.second << NL;
186 /// Register checker.
187 void ento::registerObjCContainersChecker(CheckerManager &mgr) {
188 mgr.registerChecker<ObjCContainersChecker>();