634c12d23f
- (bounded copies) Be more conservative about how much is being copied. - (str(n)cat) If we can't compute the exact final length of an append operation, we can still lower-bound it. - (stpcpy) Fix the conjured return value at the end to actually be returned. This requires these supporting changes: - C string metadata symbols are still live even when buried in a SymExpr. - "Hypothetical" C string lengths, to represent a value that /will/ be passed to setCStringLength() if all goes well. (The idea is to allow for temporary constrainable symbols that may end up becoming permanent.) - The 'checkAdditionOverflow' helper makes sure that the two strings being appended in a strcat don't overflow size_t. This should never *actually* happen; the real effect is to keep the final string length from "wrapping around" in the constraint manager. This doesn't actually test the "bounded" operations (strncpy and strncat) because they can leave strings unterminated. Next on the list! llvm-svn: 133046
1667 lines
62 KiB
C++
1667 lines
62 KiB
C++
//= CStringChecker.h - Checks calls to C string functions ----------*- C++ -*-//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This defines CStringChecker, which is an assortment of checks on calls
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// to functions in <string.h>.
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//
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//===----------------------------------------------------------------------===//
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#include "ClangSACheckers.h"
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#include "clang/StaticAnalyzer/Core/Checker.h"
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#include "clang/StaticAnalyzer/Core/CheckerManager.h"
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#include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
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#include "clang/StaticAnalyzer/Core/BugReporter/BugType.h"
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#include "clang/StaticAnalyzer/Core/PathSensitive/GRStateTrait.h"
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#include "llvm/ADT/StringSwitch.h"
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using namespace clang;
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using namespace ento;
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namespace {
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class CStringChecker : public Checker< eval::Call,
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check::PreStmt<DeclStmt>,
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check::LiveSymbols,
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check::DeadSymbols,
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check::RegionChanges
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> {
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mutable llvm::OwningPtr<BugType> BT_Null, BT_Bounds, BT_BoundsWrite,
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BT_Overlap, BT_NotCString,
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BT_AdditionOverflow;
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public:
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static void *getTag() { static int tag; return &tag; }
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bool evalCall(const CallExpr *CE, CheckerContext &C) const;
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void checkPreStmt(const DeclStmt *DS, CheckerContext &C) const;
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void checkLiveSymbols(const GRState *state, SymbolReaper &SR) const;
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void checkDeadSymbols(SymbolReaper &SR, CheckerContext &C) const;
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bool wantsRegionChangeUpdate(const GRState *state) const;
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const GRState *checkRegionChanges(const GRState *state,
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const StoreManager::InvalidatedSymbols *,
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const MemRegion * const *Begin,
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const MemRegion * const *End) const;
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typedef void (CStringChecker::*FnCheck)(CheckerContext &,
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const CallExpr *) const;
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void evalMemcpy(CheckerContext &C, const CallExpr *CE) const;
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void evalMempcpy(CheckerContext &C, const CallExpr *CE) const;
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void evalMemmove(CheckerContext &C, const CallExpr *CE) const;
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void evalBcopy(CheckerContext &C, const CallExpr *CE) const;
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void evalCopyCommon(CheckerContext &C, const CallExpr *CE,
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const GRState *state,
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const Expr *Size, const Expr *Source, const Expr *Dest,
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bool Restricted = false,
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bool IsMempcpy = false) const;
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void evalMemcmp(CheckerContext &C, const CallExpr *CE) const;
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void evalstrLength(CheckerContext &C, const CallExpr *CE) const;
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void evalstrnLength(CheckerContext &C, const CallExpr *CE) const;
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void evalstrLengthCommon(CheckerContext &C, const CallExpr *CE,
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bool IsStrnlen = false) const;
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void evalStrcpy(CheckerContext &C, const CallExpr *CE) const;
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void evalStrncpy(CheckerContext &C, const CallExpr *CE) const;
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void evalStpcpy(CheckerContext &C, const CallExpr *CE) const;
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void evalStrcpyCommon(CheckerContext &C, const CallExpr *CE, bool returnEnd,
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bool isBounded, bool isAppending) const;
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void evalStrcat(CheckerContext &C, const CallExpr *CE) const;
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void evalStrncat(CheckerContext &C, const CallExpr *CE) const;
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void evalStrcmp(CheckerContext &C, const CallExpr *CE) const;
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void evalStrncmp(CheckerContext &C, const CallExpr *CE) const;
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void evalStrcasecmp(CheckerContext &C, const CallExpr *CE) const;
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void evalStrncasecmp(CheckerContext &C, const CallExpr *CE) const;
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void evalStrcmpCommon(CheckerContext &C, const CallExpr *CE,
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bool isBounded = false, bool ignoreCase = false) const;
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// Utility methods
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std::pair<const GRState*, const GRState*>
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static assumeZero(CheckerContext &C,
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const GRState *state, SVal V, QualType Ty);
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static const GRState *setCStringLength(const GRState *state,
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const MemRegion *MR, SVal strLength);
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static SVal getCStringLengthForRegion(CheckerContext &C,
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const GRState *&state,
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const Expr *Ex, const MemRegion *MR,
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bool hypothetical);
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SVal getCStringLength(CheckerContext &C, const GRState *&state,
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const Expr *Ex, SVal Buf,
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bool hypothetical = false) const;
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const StringLiteral *getCStringLiteral(CheckerContext &C,
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const GRState *&state,
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const Expr *expr,
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SVal val) const;
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static const GRState *InvalidateBuffer(CheckerContext &C,
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const GRState *state,
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const Expr *Ex, SVal V);
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static bool SummarizeRegion(llvm::raw_ostream& os, ASTContext& Ctx,
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const MemRegion *MR);
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// Re-usable checks
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const GRState *checkNonNull(CheckerContext &C, const GRState *state,
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const Expr *S, SVal l) const;
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const GRState *CheckLocation(CheckerContext &C, const GRState *state,
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const Expr *S, SVal l,
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bool IsDestination = false) const;
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const GRState *CheckBufferAccess(CheckerContext &C, const GRState *state,
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const Expr *Size,
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const Expr *FirstBuf,
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const Expr *SecondBuf = NULL,
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bool FirstIsDestination = false) const;
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const GRState *CheckOverlap(CheckerContext &C, const GRState *state,
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const Expr *Size, const Expr *First,
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const Expr *Second) const;
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void emitOverlapBug(CheckerContext &C, const GRState *state,
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const Stmt *First, const Stmt *Second) const;
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const GRState *checkAdditionOverflow(CheckerContext &C, const GRState *state,
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NonLoc left, NonLoc right) const;
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};
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class CStringLength {
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public:
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typedef llvm::ImmutableMap<const MemRegion *, SVal> EntryMap;
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};
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} //end anonymous namespace
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namespace clang {
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namespace ento {
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template <>
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struct GRStateTrait<CStringLength>
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: public GRStatePartialTrait<CStringLength::EntryMap> {
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static void *GDMIndex() { return CStringChecker::getTag(); }
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};
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}
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}
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//===----------------------------------------------------------------------===//
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// Individual checks and utility methods.
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//===----------------------------------------------------------------------===//
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std::pair<const GRState*, const GRState*>
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CStringChecker::assumeZero(CheckerContext &C, const GRState *state, SVal V,
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QualType Ty) {
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DefinedSVal *val = dyn_cast<DefinedSVal>(&V);
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if (!val)
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return std::pair<const GRState*, const GRState *>(state, state);
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SValBuilder &svalBuilder = C.getSValBuilder();
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DefinedOrUnknownSVal zero = svalBuilder.makeZeroVal(Ty);
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return state->assume(svalBuilder.evalEQ(state, *val, zero));
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}
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const GRState *CStringChecker::checkNonNull(CheckerContext &C,
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const GRState *state,
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const Expr *S, SVal l) const {
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// If a previous check has failed, propagate the failure.
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if (!state)
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return NULL;
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const GRState *stateNull, *stateNonNull;
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llvm::tie(stateNull, stateNonNull) = assumeZero(C, state, l, S->getType());
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if (stateNull && !stateNonNull) {
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ExplodedNode *N = C.generateSink(stateNull);
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if (!N)
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return NULL;
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if (!BT_Null)
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BT_Null.reset(new BuiltinBug("API",
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"Null pointer argument in call to byte string function"));
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// Generate a report for this bug.
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BuiltinBug *BT = static_cast<BuiltinBug*>(BT_Null.get());
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EnhancedBugReport *report = new EnhancedBugReport(*BT,
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BT->getDescription(), N);
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report->addRange(S->getSourceRange());
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report->addVisitorCreator(bugreporter::registerTrackNullOrUndefValue, S);
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C.EmitReport(report);
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return NULL;
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}
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// From here on, assume that the value is non-null.
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assert(stateNonNull);
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return stateNonNull;
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}
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// FIXME: This was originally copied from ArrayBoundChecker.cpp. Refactor?
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const GRState *CStringChecker::CheckLocation(CheckerContext &C,
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const GRState *state,
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const Expr *S, SVal l,
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bool IsDestination) const {
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// If a previous check has failed, propagate the failure.
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if (!state)
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return NULL;
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// Check for out of bound array element access.
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const MemRegion *R = l.getAsRegion();
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if (!R)
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return state;
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const ElementRegion *ER = dyn_cast<ElementRegion>(R);
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if (!ER)
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return state;
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assert(ER->getValueType() == C.getASTContext().CharTy &&
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"CheckLocation should only be called with char* ElementRegions");
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// Get the size of the array.
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const SubRegion *superReg = cast<SubRegion>(ER->getSuperRegion());
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SValBuilder &svalBuilder = C.getSValBuilder();
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SVal Extent = svalBuilder.convertToArrayIndex(superReg->getExtent(svalBuilder));
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DefinedOrUnknownSVal Size = cast<DefinedOrUnknownSVal>(Extent);
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// Get the index of the accessed element.
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DefinedOrUnknownSVal Idx = cast<DefinedOrUnknownSVal>(ER->getIndex());
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const GRState *StInBound = state->assumeInBound(Idx, Size, true);
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const GRState *StOutBound = state->assumeInBound(Idx, Size, false);
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if (StOutBound && !StInBound) {
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ExplodedNode *N = C.generateSink(StOutBound);
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if (!N)
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return NULL;
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BuiltinBug *BT;
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if (IsDestination) {
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if (!BT_BoundsWrite) {
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BT_BoundsWrite.reset(new BuiltinBug("Out-of-bound array access",
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"Byte string function overflows destination buffer"));
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}
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BT = static_cast<BuiltinBug*>(BT_BoundsWrite.get());
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} else {
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if (!BT_Bounds) {
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BT_Bounds.reset(new BuiltinBug("Out-of-bound array access",
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"Byte string function accesses out-of-bound array element"));
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}
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BT = static_cast<BuiltinBug*>(BT_Bounds.get());
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}
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// FIXME: It would be nice to eventually make this diagnostic more clear,
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// e.g., by referencing the original declaration or by saying *why* this
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// reference is outside the range.
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// Generate a report for this bug.
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RangedBugReport *report = new RangedBugReport(*BT, BT->getDescription(), N);
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report->addRange(S->getSourceRange());
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C.EmitReport(report);
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return NULL;
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}
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// Array bound check succeeded. From this point forward the array bound
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// should always succeed.
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return StInBound;
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}
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const GRState *CStringChecker::CheckBufferAccess(CheckerContext &C,
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const GRState *state,
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const Expr *Size,
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const Expr *FirstBuf,
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const Expr *SecondBuf,
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bool FirstIsDestination) const {
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// If a previous check has failed, propagate the failure.
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if (!state)
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return NULL;
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SValBuilder &svalBuilder = C.getSValBuilder();
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ASTContext &Ctx = C.getASTContext();
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QualType sizeTy = Size->getType();
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QualType PtrTy = Ctx.getPointerType(Ctx.CharTy);
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// Check that the first buffer is non-null.
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SVal BufVal = state->getSVal(FirstBuf);
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state = checkNonNull(C, state, FirstBuf, BufVal);
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if (!state)
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return NULL;
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// Get the access length and make sure it is known.
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SVal LengthVal = state->getSVal(Size);
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NonLoc *Length = dyn_cast<NonLoc>(&LengthVal);
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if (!Length)
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return state;
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// Compute the offset of the last element to be accessed: size-1.
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NonLoc One = cast<NonLoc>(svalBuilder.makeIntVal(1, sizeTy));
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NonLoc LastOffset = cast<NonLoc>(svalBuilder.evalBinOpNN(state, BO_Sub,
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*Length, One, sizeTy));
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// Check that the first buffer is sufficiently long.
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SVal BufStart = svalBuilder.evalCast(BufVal, PtrTy, FirstBuf->getType());
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if (Loc *BufLoc = dyn_cast<Loc>(&BufStart)) {
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SVal BufEnd = svalBuilder.evalBinOpLN(state, BO_Add, *BufLoc,
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LastOffset, PtrTy);
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state = CheckLocation(C, state, FirstBuf, BufEnd, FirstIsDestination);
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// If the buffer isn't large enough, abort.
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if (!state)
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return NULL;
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}
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// If there's a second buffer, check it as well.
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if (SecondBuf) {
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BufVal = state->getSVal(SecondBuf);
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state = checkNonNull(C, state, SecondBuf, BufVal);
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if (!state)
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return NULL;
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BufStart = svalBuilder.evalCast(BufVal, PtrTy, SecondBuf->getType());
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if (Loc *BufLoc = dyn_cast<Loc>(&BufStart)) {
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SVal BufEnd = svalBuilder.evalBinOpLN(state, BO_Add, *BufLoc,
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LastOffset, PtrTy);
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state = CheckLocation(C, state, SecondBuf, BufEnd);
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}
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}
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// Large enough or not, return this state!
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return state;
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}
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const GRState *CStringChecker::CheckOverlap(CheckerContext &C,
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const GRState *state,
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const Expr *Size,
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const Expr *First,
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const Expr *Second) const {
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// Do a simple check for overlap: if the two arguments are from the same
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// buffer, see if the end of the first is greater than the start of the second
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// or vice versa.
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// If a previous check has failed, propagate the failure.
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if (!state)
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return NULL;
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const GRState *stateTrue, *stateFalse;
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// Get the buffer values and make sure they're known locations.
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SVal firstVal = state->getSVal(First);
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SVal secondVal = state->getSVal(Second);
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Loc *firstLoc = dyn_cast<Loc>(&firstVal);
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if (!firstLoc)
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return state;
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Loc *secondLoc = dyn_cast<Loc>(&secondVal);
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if (!secondLoc)
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return state;
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// Are the two values the same?
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SValBuilder &svalBuilder = C.getSValBuilder();
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llvm::tie(stateTrue, stateFalse) =
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state->assume(svalBuilder.evalEQ(state, *firstLoc, *secondLoc));
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if (stateTrue && !stateFalse) {
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// If the values are known to be equal, that's automatically an overlap.
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emitOverlapBug(C, stateTrue, First, Second);
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return NULL;
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}
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// assume the two expressions are not equal.
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assert(stateFalse);
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state = stateFalse;
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// Which value comes first?
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ASTContext &Ctx = svalBuilder.getContext();
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QualType cmpTy = Ctx.IntTy;
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SVal reverse = svalBuilder.evalBinOpLL(state, BO_GT,
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*firstLoc, *secondLoc, cmpTy);
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DefinedOrUnknownSVal *reverseTest = dyn_cast<DefinedOrUnknownSVal>(&reverse);
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if (!reverseTest)
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return state;
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llvm::tie(stateTrue, stateFalse) = state->assume(*reverseTest);
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if (stateTrue) {
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if (stateFalse) {
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// If we don't know which one comes first, we can't perform this test.
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return state;
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} else {
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// Switch the values so that firstVal is before secondVal.
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Loc *tmpLoc = firstLoc;
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firstLoc = secondLoc;
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secondLoc = tmpLoc;
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// Switch the Exprs as well, so that they still correspond.
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const Expr *tmpExpr = First;
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First = Second;
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Second = tmpExpr;
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}
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}
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// Get the length, and make sure it too is known.
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SVal LengthVal = state->getSVal(Size);
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NonLoc *Length = dyn_cast<NonLoc>(&LengthVal);
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if (!Length)
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return state;
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// Convert the first buffer's start address to char*.
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// Bail out if the cast fails.
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QualType CharPtrTy = Ctx.getPointerType(Ctx.CharTy);
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SVal FirstStart = svalBuilder.evalCast(*firstLoc, CharPtrTy, First->getType());
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Loc *FirstStartLoc = dyn_cast<Loc>(&FirstStart);
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if (!FirstStartLoc)
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return state;
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// Compute the end of the first buffer. Bail out if THAT fails.
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SVal FirstEnd = svalBuilder.evalBinOpLN(state, BO_Add,
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*FirstStartLoc, *Length, CharPtrTy);
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Loc *FirstEndLoc = dyn_cast<Loc>(&FirstEnd);
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if (!FirstEndLoc)
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return state;
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// Is the end of the first buffer past the start of the second buffer?
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SVal Overlap = svalBuilder.evalBinOpLL(state, BO_GT,
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*FirstEndLoc, *secondLoc, cmpTy);
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DefinedOrUnknownSVal *OverlapTest = dyn_cast<DefinedOrUnknownSVal>(&Overlap);
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if (!OverlapTest)
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return state;
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llvm::tie(stateTrue, stateFalse) = state->assume(*OverlapTest);
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if (stateTrue && !stateFalse) {
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// Overlap!
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emitOverlapBug(C, stateTrue, First, Second);
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return NULL;
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}
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// assume the two expressions don't overlap.
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assert(stateFalse);
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return stateFalse;
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}
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void CStringChecker::emitOverlapBug(CheckerContext &C, const GRState *state,
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const Stmt *First, const Stmt *Second) const {
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ExplodedNode *N = C.generateSink(state);
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if (!N)
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return;
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if (!BT_Overlap)
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BT_Overlap.reset(new BugType("Unix API", "Improper arguments"));
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// Generate a report for this bug.
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RangedBugReport *report =
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new RangedBugReport(*BT_Overlap,
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"Arguments must not be overlapping buffers", N);
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report->addRange(First->getSourceRange());
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report->addRange(Second->getSourceRange());
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C.EmitReport(report);
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}
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const GRState *CStringChecker::checkAdditionOverflow(CheckerContext &C,
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const GRState *state,
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NonLoc left,
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NonLoc right) const {
|
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// If a previous check has failed, propagate the failure.
|
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if (!state)
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return NULL;
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SValBuilder &svalBuilder = C.getSValBuilder();
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BasicValueFactory &BVF = svalBuilder.getBasicValueFactory();
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QualType sizeTy = svalBuilder.getContext().getSizeType();
|
|
const llvm::APSInt &maxValInt = BVF.getMaxValue(sizeTy);
|
|
NonLoc maxVal = svalBuilder.makeIntVal(maxValInt);
|
|
|
|
SVal maxMinusRight = svalBuilder.evalBinOpNN(state, BO_Sub, maxVal, right,
|
|
sizeTy);
|
|
|
|
if (maxMinusRight.isUnknownOrUndef()) {
|
|
// Try switching the operands. (The order of these two assignments is
|
|
// important!)
|
|
maxMinusRight = svalBuilder.evalBinOpNN(state, BO_Sub, maxVal, left,
|
|
sizeTy);
|
|
left = right;
|
|
}
|
|
|
|
if (NonLoc *maxMinusRightNL = dyn_cast<NonLoc>(&maxMinusRight)) {
|
|
QualType cmpTy = svalBuilder.getConditionType();
|
|
// If left > max - right, we have an overflow.
|
|
SVal willOverflow = svalBuilder.evalBinOpNN(state, BO_GT, left,
|
|
*maxMinusRightNL, cmpTy);
|
|
|
|
const GRState *stateOverflow, *stateOkay;
|
|
llvm::tie(stateOverflow, stateOkay) =
|
|
state->assume(cast<DefinedOrUnknownSVal>(willOverflow));
|
|
|
|
if (stateOverflow && !stateOkay) {
|
|
// We have an overflow. Emit a bug report.
|
|
ExplodedNode *N = C.generateSink(stateOverflow);
|
|
if (!N)
|
|
return NULL;
|
|
|
|
if (!BT_AdditionOverflow)
|
|
BT_AdditionOverflow.reset(new BuiltinBug("API",
|
|
"Sum of expressions causes overflow"));
|
|
|
|
llvm::SmallString<120> buf;
|
|
llvm::raw_svector_ostream os(buf);
|
|
// This isn't a great error message, but this should never occur in real
|
|
// code anyway -- you'd have to create a buffer longer than a size_t can
|
|
// represent, which is sort of a contradiction.
|
|
os << "This expression will create a string whose length is too big to "
|
|
<< "be represented as a size_t";
|
|
|
|
// Generate a report for this bug.
|
|
BugReport *report = new BugReport(*BT_AdditionOverflow, os.str(), N);
|
|
C.EmitReport(report);
|
|
|
|
return NULL;
|
|
}
|
|
|
|
// From now on, assume an overflow didn't occur.
|
|
assert(stateOkay);
|
|
state = stateOkay;
|
|
}
|
|
|
|
return state;
|
|
}
|
|
|
|
const GRState *CStringChecker::setCStringLength(const GRState *state,
|
|
const MemRegion *MR,
|
|
SVal strLength) {
|
|
assert(!strLength.isUndef() && "Attempt to set an undefined string length");
|
|
|
|
MR = MR->StripCasts();
|
|
|
|
switch (MR->getKind()) {
|
|
case MemRegion::StringRegionKind:
|
|
// FIXME: This can happen if we strcpy() into a string region. This is
|
|
// undefined [C99 6.4.5p6], but we should still warn about it.
|
|
return state;
|
|
|
|
case MemRegion::SymbolicRegionKind:
|
|
case MemRegion::AllocaRegionKind:
|
|
case MemRegion::VarRegionKind:
|
|
case MemRegion::FieldRegionKind:
|
|
case MemRegion::ObjCIvarRegionKind:
|
|
// These are the types we can currently track string lengths for.
|
|
break;
|
|
|
|
case MemRegion::ElementRegionKind:
|
|
// FIXME: Handle element regions by upper-bounding the parent region's
|
|
// string length.
|
|
return state;
|
|
|
|
default:
|
|
// Other regions (mostly non-data) can't have a reliable C string length.
|
|
// For now, just ignore the change.
|
|
// FIXME: These are rare but not impossible. We should output some kind of
|
|
// warning for things like strcpy((char[]){'a', 0}, "b");
|
|
return state;
|
|
}
|
|
|
|
if (strLength.isUnknown())
|
|
return state->remove<CStringLength>(MR);
|
|
|
|
return state->set<CStringLength>(MR, strLength);
|
|
}
|
|
|
|
SVal CStringChecker::getCStringLengthForRegion(CheckerContext &C,
|
|
const GRState *&state,
|
|
const Expr *Ex,
|
|
const MemRegion *MR,
|
|
bool hypothetical) {
|
|
if (!hypothetical) {
|
|
// If there's a recorded length, go ahead and return it.
|
|
const SVal *Recorded = state->get<CStringLength>(MR);
|
|
if (Recorded)
|
|
return *Recorded;
|
|
}
|
|
|
|
// Otherwise, get a new symbol and update the state.
|
|
unsigned Count = C.getNodeBuilder().getCurrentBlockCount();
|
|
SValBuilder &svalBuilder = C.getSValBuilder();
|
|
QualType sizeTy = svalBuilder.getContext().getSizeType();
|
|
SVal strLength = svalBuilder.getMetadataSymbolVal(CStringChecker::getTag(),
|
|
MR, Ex, sizeTy, Count);
|
|
|
|
if (!hypothetical)
|
|
state = state->set<CStringLength>(MR, strLength);
|
|
|
|
return strLength;
|
|
}
|
|
|
|
SVal CStringChecker::getCStringLength(CheckerContext &C, const GRState *&state,
|
|
const Expr *Ex, SVal Buf,
|
|
bool hypothetical) const {
|
|
const MemRegion *MR = Buf.getAsRegion();
|
|
if (!MR) {
|
|
// If we can't get a region, see if it's something we /know/ isn't a
|
|
// C string. In the context of locations, the only time we can issue such
|
|
// a warning is for labels.
|
|
if (loc::GotoLabel *Label = dyn_cast<loc::GotoLabel>(&Buf)) {
|
|
if (ExplodedNode *N = C.generateNode(state)) {
|
|
if (!BT_NotCString)
|
|
BT_NotCString.reset(new BuiltinBug("API",
|
|
"Argument is not a null-terminated string."));
|
|
|
|
llvm::SmallString<120> buf;
|
|
llvm::raw_svector_ostream os(buf);
|
|
os << "Argument to byte string function is the address of the label '"
|
|
<< Label->getLabel()->getName()
|
|
<< "', which is not a null-terminated string";
|
|
|
|
// Generate a report for this bug.
|
|
EnhancedBugReport *report = new EnhancedBugReport(*BT_NotCString,
|
|
os.str(), N);
|
|
|
|
report->addRange(Ex->getSourceRange());
|
|
C.EmitReport(report);
|
|
}
|
|
|
|
return UndefinedVal();
|
|
}
|
|
|
|
// If it's not a region and not a label, give up.
|
|
return UnknownVal();
|
|
}
|
|
|
|
// If we have a region, strip casts from it and see if we can figure out
|
|
// its length. For anything we can't figure out, just return UnknownVal.
|
|
MR = MR->StripCasts();
|
|
|
|
switch (MR->getKind()) {
|
|
case MemRegion::StringRegionKind: {
|
|
// Modifying the contents of string regions is undefined [C99 6.4.5p6],
|
|
// so we can assume that the byte length is the correct C string length.
|
|
SValBuilder &svalBuilder = C.getSValBuilder();
|
|
QualType sizeTy = svalBuilder.getContext().getSizeType();
|
|
const StringLiteral *strLit = cast<StringRegion>(MR)->getStringLiteral();
|
|
return svalBuilder.makeIntVal(strLit->getByteLength(), sizeTy);
|
|
}
|
|
case MemRegion::SymbolicRegionKind:
|
|
case MemRegion::AllocaRegionKind:
|
|
case MemRegion::VarRegionKind:
|
|
case MemRegion::FieldRegionKind:
|
|
case MemRegion::ObjCIvarRegionKind:
|
|
return getCStringLengthForRegion(C, state, Ex, MR, hypothetical);
|
|
case MemRegion::CompoundLiteralRegionKind:
|
|
// FIXME: Can we track this? Is it necessary?
|
|
return UnknownVal();
|
|
case MemRegion::ElementRegionKind:
|
|
// FIXME: How can we handle this? It's not good enough to subtract the
|
|
// offset from the base string length; consider "123\x00567" and &a[5].
|
|
return UnknownVal();
|
|
default:
|
|
// Other regions (mostly non-data) can't have a reliable C string length.
|
|
// In this case, an error is emitted and UndefinedVal is returned.
|
|
// The caller should always be prepared to handle this case.
|
|
if (ExplodedNode *N = C.generateNode(state)) {
|
|
if (!BT_NotCString)
|
|
BT_NotCString.reset(new BuiltinBug("API",
|
|
"Argument is not a null-terminated string."));
|
|
|
|
llvm::SmallString<120> buf;
|
|
llvm::raw_svector_ostream os(buf);
|
|
|
|
os << "Argument to byte string function is ";
|
|
|
|
if (SummarizeRegion(os, C.getASTContext(), MR))
|
|
os << ", which is not a null-terminated string";
|
|
else
|
|
os << "not a null-terminated string";
|
|
|
|
// Generate a report for this bug.
|
|
EnhancedBugReport *report = new EnhancedBugReport(*BT_NotCString,
|
|
os.str(), N);
|
|
|
|
report->addRange(Ex->getSourceRange());
|
|
C.EmitReport(report);
|
|
}
|
|
|
|
return UndefinedVal();
|
|
}
|
|
}
|
|
|
|
const StringLiteral *CStringChecker::getCStringLiteral(CheckerContext &C,
|
|
const GRState *&state, const Expr *expr, SVal val) const {
|
|
|
|
// Get the memory region pointed to by the val.
|
|
const MemRegion *bufRegion = val.getAsRegion();
|
|
if (!bufRegion)
|
|
return NULL;
|
|
|
|
// Strip casts off the memory region.
|
|
bufRegion = bufRegion->StripCasts();
|
|
|
|
// Cast the memory region to a string region.
|
|
const StringRegion *strRegion= dyn_cast<StringRegion>(bufRegion);
|
|
if (!strRegion)
|
|
return NULL;
|
|
|
|
// Return the actual string in the string region.
|
|
return strRegion->getStringLiteral();
|
|
}
|
|
|
|
const GRState *CStringChecker::InvalidateBuffer(CheckerContext &C,
|
|
const GRState *state,
|
|
const Expr *E, SVal V) {
|
|
Loc *L = dyn_cast<Loc>(&V);
|
|
if (!L)
|
|
return state;
|
|
|
|
// FIXME: This is a simplified version of what's in CFRefCount.cpp -- it makes
|
|
// some assumptions about the value that CFRefCount can't. Even so, it should
|
|
// probably be refactored.
|
|
if (loc::MemRegionVal* MR = dyn_cast<loc::MemRegionVal>(L)) {
|
|
const MemRegion *R = MR->getRegion()->StripCasts();
|
|
|
|
// Are we dealing with an ElementRegion? If so, we should be invalidating
|
|
// the super-region.
|
|
if (const ElementRegion *ER = dyn_cast<ElementRegion>(R)) {
|
|
R = ER->getSuperRegion();
|
|
// FIXME: What about layers of ElementRegions?
|
|
}
|
|
|
|
// Invalidate this region.
|
|
unsigned Count = C.getNodeBuilder().getCurrentBlockCount();
|
|
return state->invalidateRegion(R, E, Count, NULL);
|
|
}
|
|
|
|
// If we have a non-region value by chance, just remove the binding.
|
|
// FIXME: is this necessary or correct? This handles the non-Region
|
|
// cases. Is it ever valid to store to these?
|
|
return state->unbindLoc(*L);
|
|
}
|
|
|
|
bool CStringChecker::SummarizeRegion(llvm::raw_ostream& os, ASTContext& Ctx,
|
|
const MemRegion *MR) {
|
|
const TypedRegion *TR = dyn_cast<TypedRegion>(MR);
|
|
if (!TR)
|
|
return false;
|
|
|
|
switch (TR->getKind()) {
|
|
case MemRegion::FunctionTextRegionKind: {
|
|
const FunctionDecl *FD = cast<FunctionTextRegion>(TR)->getDecl();
|
|
if (FD)
|
|
os << "the address of the function '" << FD << "'";
|
|
else
|
|
os << "the address of a function";
|
|
return true;
|
|
}
|
|
case MemRegion::BlockTextRegionKind:
|
|
os << "block text";
|
|
return true;
|
|
case MemRegion::BlockDataRegionKind:
|
|
os << "a block";
|
|
return true;
|
|
case MemRegion::CXXThisRegionKind:
|
|
case MemRegion::CXXTempObjectRegionKind:
|
|
os << "a C++ temp object of type " << TR->getValueType().getAsString();
|
|
return true;
|
|
case MemRegion::VarRegionKind:
|
|
os << "a variable of type" << TR->getValueType().getAsString();
|
|
return true;
|
|
case MemRegion::FieldRegionKind:
|
|
os << "a field of type " << TR->getValueType().getAsString();
|
|
return true;
|
|
case MemRegion::ObjCIvarRegionKind:
|
|
os << "an instance variable of type " << TR->getValueType().getAsString();
|
|
return true;
|
|
default:
|
|
return false;
|
|
}
|
|
}
|
|
|
|
//===----------------------------------------------------------------------===//
|
|
// evaluation of individual function calls.
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
void CStringChecker::evalCopyCommon(CheckerContext &C,
|
|
const CallExpr *CE,
|
|
const GRState *state,
|
|
const Expr *Size, const Expr *Dest,
|
|
const Expr *Source, bool Restricted,
|
|
bool IsMempcpy) const {
|
|
// See if the size argument is zero.
|
|
SVal sizeVal = state->getSVal(Size);
|
|
QualType sizeTy = Size->getType();
|
|
|
|
const GRState *stateZeroSize, *stateNonZeroSize;
|
|
llvm::tie(stateZeroSize, stateNonZeroSize) = assumeZero(C, state, sizeVal, sizeTy);
|
|
|
|
// Get the value of the Dest.
|
|
SVal destVal = state->getSVal(Dest);
|
|
|
|
// If the size is zero, there won't be any actual memory access, so
|
|
// just bind the return value to the destination buffer and return.
|
|
if (stateZeroSize) {
|
|
stateZeroSize = stateZeroSize->BindExpr(CE, destVal);
|
|
C.addTransition(stateZeroSize);
|
|
}
|
|
|
|
// If the size can be nonzero, we have to check the other arguments.
|
|
if (stateNonZeroSize) {
|
|
state = stateNonZeroSize;
|
|
|
|
// Ensure the destination is not null. If it is NULL there will be a
|
|
// NULL pointer dereference.
|
|
state = checkNonNull(C, state, Dest, destVal);
|
|
if (!state)
|
|
return;
|
|
|
|
// Get the value of the Src.
|
|
SVal srcVal = state->getSVal(Source);
|
|
|
|
// Ensure the source is not null. If it is NULL there will be a
|
|
// NULL pointer dereference.
|
|
state = checkNonNull(C, state, Source, srcVal);
|
|
if (!state)
|
|
return;
|
|
|
|
// Ensure the accesses are valid and that the buffers do not overlap.
|
|
state = CheckBufferAccess(C, state, Size, Dest, Source,
|
|
/* FirstIsDst = */ true);
|
|
if (Restricted)
|
|
state = CheckOverlap(C, state, Size, Dest, Source);
|
|
|
|
if (!state)
|
|
return;
|
|
|
|
// If this is mempcpy, get the byte after the last byte copied and
|
|
// bind the expr.
|
|
if (IsMempcpy) {
|
|
loc::MemRegionVal *destRegVal = dyn_cast<loc::MemRegionVal>(&destVal);
|
|
assert(destRegVal && "Destination should be a known MemRegionVal here");
|
|
|
|
// Get the length to copy.
|
|
NonLoc *lenValNonLoc = dyn_cast<NonLoc>(&sizeVal);
|
|
|
|
if (lenValNonLoc) {
|
|
// Get the byte after the last byte copied.
|
|
SVal lastElement = C.getSValBuilder().evalBinOpLN(state, BO_Add,
|
|
*destRegVal,
|
|
*lenValNonLoc,
|
|
Dest->getType());
|
|
|
|
// The byte after the last byte copied is the return value.
|
|
state = state->BindExpr(CE, lastElement);
|
|
} else {
|
|
// If we don't know how much we copied, we can at least
|
|
// conjure a return value for later.
|
|
unsigned Count = C.getNodeBuilder().getCurrentBlockCount();
|
|
SVal result =
|
|
C.getSValBuilder().getConjuredSymbolVal(NULL, CE, Count);
|
|
state = state->BindExpr(CE, result);
|
|
}
|
|
|
|
} else {
|
|
// All other copies return the destination buffer.
|
|
// (Well, bcopy() has a void return type, but this won't hurt.)
|
|
state = state->BindExpr(CE, destVal);
|
|
}
|
|
|
|
// Invalidate the destination.
|
|
// FIXME: Even if we can't perfectly model the copy, we should see if we
|
|
// can use LazyCompoundVals to copy the source values into the destination.
|
|
// This would probably remove any existing bindings past the end of the
|
|
// copied region, but that's still an improvement over blank invalidation.
|
|
state = InvalidateBuffer(C, state, Dest, state->getSVal(Dest));
|
|
C.addTransition(state);
|
|
}
|
|
}
|
|
|
|
|
|
void CStringChecker::evalMemcpy(CheckerContext &C, const CallExpr *CE) const {
|
|
// void *memcpy(void *restrict dst, const void *restrict src, size_t n);
|
|
// The return value is the address of the destination buffer.
|
|
const Expr *Dest = CE->getArg(0);
|
|
const GRState *state = C.getState();
|
|
|
|
evalCopyCommon(C, CE, state, CE->getArg(2), Dest, CE->getArg(1), true);
|
|
}
|
|
|
|
void CStringChecker::evalMempcpy(CheckerContext &C, const CallExpr *CE) const {
|
|
// void *mempcpy(void *restrict dst, const void *restrict src, size_t n);
|
|
// The return value is a pointer to the byte following the last written byte.
|
|
const Expr *Dest = CE->getArg(0);
|
|
const GRState *state = C.getState();
|
|
|
|
evalCopyCommon(C, CE, state, CE->getArg(2), Dest, CE->getArg(1), true, true);
|
|
}
|
|
|
|
void CStringChecker::evalMemmove(CheckerContext &C, const CallExpr *CE) const {
|
|
// void *memmove(void *dst, const void *src, size_t n);
|
|
// The return value is the address of the destination buffer.
|
|
const Expr *Dest = CE->getArg(0);
|
|
const GRState *state = C.getState();
|
|
|
|
evalCopyCommon(C, CE, state, CE->getArg(2), Dest, CE->getArg(1));
|
|
}
|
|
|
|
void CStringChecker::evalBcopy(CheckerContext &C, const CallExpr *CE) const {
|
|
// void bcopy(const void *src, void *dst, size_t n);
|
|
evalCopyCommon(C, CE, C.getState(),
|
|
CE->getArg(2), CE->getArg(1), CE->getArg(0));
|
|
}
|
|
|
|
void CStringChecker::evalMemcmp(CheckerContext &C, const CallExpr *CE) const {
|
|
// int memcmp(const void *s1, const void *s2, size_t n);
|
|
const Expr *Left = CE->getArg(0);
|
|
const Expr *Right = CE->getArg(1);
|
|
const Expr *Size = CE->getArg(2);
|
|
|
|
const GRState *state = C.getState();
|
|
SValBuilder &svalBuilder = C.getSValBuilder();
|
|
|
|
// See if the size argument is zero.
|
|
SVal sizeVal = state->getSVal(Size);
|
|
QualType sizeTy = Size->getType();
|
|
|
|
const GRState *stateZeroSize, *stateNonZeroSize;
|
|
llvm::tie(stateZeroSize, stateNonZeroSize) =
|
|
assumeZero(C, state, sizeVal, sizeTy);
|
|
|
|
// If the size can be zero, the result will be 0 in that case, and we don't
|
|
// have to check either of the buffers.
|
|
if (stateZeroSize) {
|
|
state = stateZeroSize;
|
|
state = state->BindExpr(CE, svalBuilder.makeZeroVal(CE->getType()));
|
|
C.addTransition(state);
|
|
}
|
|
|
|
// If the size can be nonzero, we have to check the other arguments.
|
|
if (stateNonZeroSize) {
|
|
state = stateNonZeroSize;
|
|
// If we know the two buffers are the same, we know the result is 0.
|
|
// First, get the two buffers' addresses. Another checker will have already
|
|
// made sure they're not undefined.
|
|
DefinedOrUnknownSVal LV = cast<DefinedOrUnknownSVal>(state->getSVal(Left));
|
|
DefinedOrUnknownSVal RV = cast<DefinedOrUnknownSVal>(state->getSVal(Right));
|
|
|
|
// See if they are the same.
|
|
DefinedOrUnknownSVal SameBuf = svalBuilder.evalEQ(state, LV, RV);
|
|
const GRState *StSameBuf, *StNotSameBuf;
|
|
llvm::tie(StSameBuf, StNotSameBuf) = state->assume(SameBuf);
|
|
|
|
// If the two arguments might be the same buffer, we know the result is zero,
|
|
// and we only need to check one size.
|
|
if (StSameBuf) {
|
|
state = StSameBuf;
|
|
state = CheckBufferAccess(C, state, Size, Left);
|
|
if (state) {
|
|
state = StSameBuf->BindExpr(CE, svalBuilder.makeZeroVal(CE->getType()));
|
|
C.addTransition(state);
|
|
}
|
|
}
|
|
|
|
// If the two arguments might be different buffers, we have to check the
|
|
// size of both of them.
|
|
if (StNotSameBuf) {
|
|
state = StNotSameBuf;
|
|
state = CheckBufferAccess(C, state, Size, Left, Right);
|
|
if (state) {
|
|
// The return value is the comparison result, which we don't know.
|
|
unsigned Count = C.getNodeBuilder().getCurrentBlockCount();
|
|
SVal CmpV = svalBuilder.getConjuredSymbolVal(NULL, CE, Count);
|
|
state = state->BindExpr(CE, CmpV);
|
|
C.addTransition(state);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
void CStringChecker::evalstrLength(CheckerContext &C,
|
|
const CallExpr *CE) const {
|
|
// size_t strlen(const char *s);
|
|
evalstrLengthCommon(C, CE, /* IsStrnlen = */ false);
|
|
}
|
|
|
|
void CStringChecker::evalstrnLength(CheckerContext &C,
|
|
const CallExpr *CE) const {
|
|
// size_t strnlen(const char *s, size_t maxlen);
|
|
evalstrLengthCommon(C, CE, /* IsStrnlen = */ true);
|
|
}
|
|
|
|
void CStringChecker::evalstrLengthCommon(CheckerContext &C, const CallExpr *CE,
|
|
bool IsStrnlen) const {
|
|
const GRState *state = C.getState();
|
|
|
|
if (IsStrnlen) {
|
|
const Expr *maxlenExpr = CE->getArg(1);
|
|
SVal maxlenVal = state->getSVal(maxlenExpr);
|
|
|
|
const GRState *stateZeroSize, *stateNonZeroSize;
|
|
llvm::tie(stateZeroSize, stateNonZeroSize) =
|
|
assumeZero(C, state, maxlenVal, maxlenExpr->getType());
|
|
|
|
// If the size can be zero, the result will be 0 in that case, and we don't
|
|
// have to check the string itself.
|
|
if (stateZeroSize) {
|
|
SVal zero = C.getSValBuilder().makeZeroVal(CE->getType());
|
|
stateZeroSize = stateZeroSize->BindExpr(CE, zero);
|
|
C.addTransition(stateZeroSize);
|
|
}
|
|
|
|
// If the size is GUARANTEED to be zero, we're done!
|
|
if (!stateNonZeroSize)
|
|
return;
|
|
|
|
// Otherwise, record the assumption that the size is nonzero.
|
|
state = stateNonZeroSize;
|
|
}
|
|
|
|
// Check that the string argument is non-null.
|
|
const Expr *Arg = CE->getArg(0);
|
|
SVal ArgVal = state->getSVal(Arg);
|
|
|
|
state = checkNonNull(C, state, Arg, ArgVal);
|
|
|
|
if (!state)
|
|
return;
|
|
|
|
SVal strLength = getCStringLength(C, state, Arg, ArgVal);
|
|
|
|
// If the argument isn't a valid C string, there's no valid state to
|
|
// transition to.
|
|
if (strLength.isUndef())
|
|
return;
|
|
|
|
DefinedOrUnknownSVal result = UnknownVal();
|
|
|
|
// If the check is for strnlen() then bind the return value to no more than
|
|
// the maxlen value.
|
|
if (IsStrnlen) {
|
|
QualType cmpTy = C.getSValBuilder().getContext().IntTy;
|
|
|
|
// It's a little unfortunate to be getting this again,
|
|
// but it's not that expensive...
|
|
const Expr *maxlenExpr = CE->getArg(1);
|
|
SVal maxlenVal = state->getSVal(maxlenExpr);
|
|
|
|
NonLoc *strLengthNL = dyn_cast<NonLoc>(&strLength);
|
|
NonLoc *maxlenValNL = dyn_cast<NonLoc>(&maxlenVal);
|
|
|
|
if (strLengthNL && maxlenValNL) {
|
|
const GRState *stateStringTooLong, *stateStringNotTooLong;
|
|
|
|
// Check if the strLength is greater than the maxlen.
|
|
llvm::tie(stateStringTooLong, stateStringNotTooLong) =
|
|
state->assume(cast<DefinedOrUnknownSVal>
|
|
(C.getSValBuilder().evalBinOpNN(state, BO_GT,
|
|
*strLengthNL,
|
|
*maxlenValNL,
|
|
cmpTy)));
|
|
|
|
if (stateStringTooLong && !stateStringNotTooLong) {
|
|
// If the string is longer than maxlen, return maxlen.
|
|
result = *maxlenValNL;
|
|
} else if (stateStringNotTooLong && !stateStringTooLong) {
|
|
// If the string is shorter than maxlen, return its length.
|
|
result = *strLengthNL;
|
|
}
|
|
}
|
|
|
|
if (result.isUnknown()) {
|
|
// If we don't have enough information for a comparison, there's
|
|
// no guarantee the full string length will actually be returned.
|
|
// All we know is the return value is the min of the string length
|
|
// and the limit. This is better than nothing.
|
|
unsigned Count = C.getNodeBuilder().getCurrentBlockCount();
|
|
result = C.getSValBuilder().getConjuredSymbolVal(NULL, CE, Count);
|
|
NonLoc *resultNL = cast<NonLoc>(&result);
|
|
|
|
if (strLengthNL) {
|
|
state = state->assume(cast<DefinedOrUnknownSVal>
|
|
(C.getSValBuilder().evalBinOpNN(state, BO_LE,
|
|
*resultNL,
|
|
*strLengthNL,
|
|
cmpTy)), true);
|
|
}
|
|
|
|
if (maxlenValNL) {
|
|
state = state->assume(cast<DefinedOrUnknownSVal>
|
|
(C.getSValBuilder().evalBinOpNN(state, BO_LE,
|
|
*resultNL,
|
|
*maxlenValNL,
|
|
cmpTy)), true);
|
|
}
|
|
}
|
|
|
|
} else {
|
|
// This is a plain strlen(), not strnlen().
|
|
result = cast<DefinedOrUnknownSVal>(strLength);
|
|
|
|
// If we don't know the length of the string, conjure a return
|
|
// value, so it can be used in constraints, at least.
|
|
if (result.isUnknown()) {
|
|
unsigned Count = C.getNodeBuilder().getCurrentBlockCount();
|
|
result = C.getSValBuilder().getConjuredSymbolVal(NULL, CE, Count);
|
|
}
|
|
}
|
|
|
|
// Bind the return value.
|
|
assert(!result.isUnknown() && "Should have conjured a value by now");
|
|
state = state->BindExpr(CE, result);
|
|
C.addTransition(state);
|
|
}
|
|
|
|
void CStringChecker::evalStrcpy(CheckerContext &C, const CallExpr *CE) const {
|
|
// char *strcpy(char *restrict dst, const char *restrict src);
|
|
evalStrcpyCommon(C, CE,
|
|
/* returnEnd = */ false,
|
|
/* isBounded = */ false,
|
|
/* isAppending = */ false);
|
|
}
|
|
|
|
void CStringChecker::evalStrncpy(CheckerContext &C, const CallExpr *CE) const {
|
|
// char *strncpy(char *restrict dst, const char *restrict src, size_t n);
|
|
evalStrcpyCommon(C, CE,
|
|
/* returnEnd = */ false,
|
|
/* isBounded = */ true,
|
|
/* isAppending = */ false);
|
|
}
|
|
|
|
void CStringChecker::evalStpcpy(CheckerContext &C, const CallExpr *CE) const {
|
|
// char *stpcpy(char *restrict dst, const char *restrict src);
|
|
evalStrcpyCommon(C, CE,
|
|
/* returnEnd = */ true,
|
|
/* isBounded = */ false,
|
|
/* isAppending = */ false);
|
|
}
|
|
|
|
void CStringChecker::evalStrcat(CheckerContext &C, const CallExpr *CE) const {
|
|
//char *strcat(char *restrict s1, const char *restrict s2);
|
|
evalStrcpyCommon(C, CE,
|
|
/* returnEnd = */ false,
|
|
/* isBounded = */ false,
|
|
/* isAppending = */ true);
|
|
}
|
|
|
|
void CStringChecker::evalStrncat(CheckerContext &C, const CallExpr *CE) const {
|
|
//char *strncat(char *restrict s1, const char *restrict s2, size_t n);
|
|
evalStrcpyCommon(C, CE,
|
|
/* returnEnd = */ false,
|
|
/* isBounded = */ true,
|
|
/* isAppending = */ true);
|
|
}
|
|
|
|
void CStringChecker::evalStrcpyCommon(CheckerContext &C, const CallExpr *CE,
|
|
bool returnEnd, bool isBounded,
|
|
bool isAppending) const {
|
|
const GRState *state = C.getState();
|
|
|
|
// Check that the destination is non-null.
|
|
const Expr *Dst = CE->getArg(0);
|
|
SVal DstVal = state->getSVal(Dst);
|
|
|
|
state = checkNonNull(C, state, Dst, DstVal);
|
|
if (!state)
|
|
return;
|
|
|
|
// Check that the source is non-null.
|
|
const Expr *srcExpr = CE->getArg(1);
|
|
SVal srcVal = state->getSVal(srcExpr);
|
|
state = checkNonNull(C, state, srcExpr, srcVal);
|
|
if (!state)
|
|
return;
|
|
|
|
// Get the string length of the source.
|
|
SVal strLength = getCStringLength(C, state, srcExpr, srcVal);
|
|
|
|
// If the source isn't a valid C string, give up.
|
|
if (strLength.isUndef())
|
|
return;
|
|
|
|
SValBuilder &svalBuilder = C.getSValBuilder();
|
|
QualType cmpTy = svalBuilder.getConditionType();
|
|
|
|
SVal amountCopied = UnknownVal();
|
|
|
|
// If the function is strncpy, strncat, etc... it is bounded.
|
|
if (isBounded) {
|
|
// Get the max number of characters to copy.
|
|
const Expr *lenExpr = CE->getArg(2);
|
|
SVal lenVal = state->getSVal(lenExpr);
|
|
|
|
// Protect against misdeclared strncpy().
|
|
lenVal = svalBuilder.evalCast(lenVal,
|
|
svalBuilder.getContext().getSizeType(),
|
|
lenExpr->getType());
|
|
|
|
NonLoc *strLengthNL = dyn_cast<NonLoc>(&strLength);
|
|
NonLoc *lenValNL = dyn_cast<NonLoc>(&lenVal);
|
|
|
|
// If we know both values, we might be able to figure out how much
|
|
// we're copying.
|
|
if (strLengthNL && lenValNL) {
|
|
const GRState *stateSourceTooLong, *stateSourceNotTooLong;
|
|
|
|
// Check if the max number to copy is less than the length of the src.
|
|
llvm::tie(stateSourceTooLong, stateSourceNotTooLong) =
|
|
state->assume(cast<DefinedOrUnknownSVal>
|
|
(svalBuilder.evalBinOpNN(state, BO_GT, *strLengthNL,
|
|
*lenValNL, cmpTy)));
|
|
|
|
if (stateSourceTooLong && !stateSourceNotTooLong) {
|
|
// Max number to copy is less than the length of the src, so the actual
|
|
// strLength copied is the max number arg.
|
|
state = stateSourceTooLong;
|
|
amountCopied = lenVal;
|
|
|
|
} else if (!stateSourceTooLong && stateSourceNotTooLong) {
|
|
// The source buffer entirely fits in the bound.
|
|
state = stateSourceNotTooLong;
|
|
amountCopied = strLength;
|
|
}
|
|
}
|
|
|
|
// If we couldn't pin down the copy length, at least bound it.
|
|
if (amountCopied.isUnknown()) {
|
|
// Try to get a "hypothetical" string length symbol, which we can later
|
|
// set as a real value if that turns out to be the case.
|
|
amountCopied = getCStringLength(C, state, lenExpr, srcVal, true);
|
|
assert(!amountCopied.isUndef());
|
|
|
|
if (NonLoc *amountCopiedNL = dyn_cast<NonLoc>(&amountCopied)) {
|
|
if (lenValNL) {
|
|
// amountCopied <= lenVal
|
|
SVal copiedLessThanBound = svalBuilder.evalBinOpNN(state, BO_LE,
|
|
*amountCopiedNL,
|
|
*lenValNL,
|
|
cmpTy);
|
|
state = state->assume(cast<DefinedOrUnknownSVal>(copiedLessThanBound),
|
|
true);
|
|
if (!state)
|
|
return;
|
|
}
|
|
|
|
if (strLengthNL) {
|
|
// amountCopied <= strlen(source)
|
|
SVal copiedLessThanSrc = svalBuilder.evalBinOpNN(state, BO_LE,
|
|
*amountCopiedNL,
|
|
*strLengthNL,
|
|
cmpTy);
|
|
state = state->assume(cast<DefinedOrUnknownSVal>(copiedLessThanSrc),
|
|
true);
|
|
if (!state)
|
|
return;
|
|
}
|
|
}
|
|
}
|
|
|
|
} else {
|
|
// The function isn't bounded. The amount copied should match the length
|
|
// of the source buffer.
|
|
amountCopied = strLength;
|
|
}
|
|
|
|
assert(state);
|
|
|
|
// This represents the number of characters copied into the destination
|
|
// buffer. (It may not actually be the strlen if the destination buffer
|
|
// is not terminated.)
|
|
SVal finalStrLength = UnknownVal();
|
|
|
|
// If this is an appending function (strcat, strncat...) then set the
|
|
// string length to strlen(src) + strlen(dst) since the buffer will
|
|
// ultimately contain both.
|
|
if (isAppending) {
|
|
// Get the string length of the destination, or give up.
|
|
SVal dstStrLength = getCStringLength(C, state, Dst, DstVal);
|
|
if (dstStrLength.isUndef())
|
|
return;
|
|
|
|
QualType sizeTy = svalBuilder.getContext().getSizeType();
|
|
|
|
NonLoc *srcStrLengthNL = dyn_cast<NonLoc>(&amountCopied);
|
|
NonLoc *dstStrLengthNL = dyn_cast<NonLoc>(&dstStrLength);
|
|
|
|
// If we know both string lengths, we might know the final string length.
|
|
if (srcStrLengthNL && dstStrLengthNL) {
|
|
// Make sure the two lengths together don't overflow a size_t.
|
|
state = checkAdditionOverflow(C, state, *srcStrLengthNL, *dstStrLengthNL);
|
|
if (!state)
|
|
return;
|
|
|
|
finalStrLength = svalBuilder.evalBinOpNN(state, BO_Add, *srcStrLengthNL,
|
|
*dstStrLengthNL, sizeTy);
|
|
}
|
|
|
|
// If we couldn't get a single value for the final string length,
|
|
// we can at least bound it by the individual lengths.
|
|
if (finalStrLength.isUnknown()) {
|
|
// Try to get a "hypothetical" string length symbol, which we can later
|
|
// set as a real value if that turns out to be the case.
|
|
finalStrLength = getCStringLength(C, state, CE, DstVal, true);
|
|
assert(!finalStrLength.isUndef());
|
|
|
|
if (NonLoc *finalStrLengthNL = dyn_cast<NonLoc>(&finalStrLength)) {
|
|
if (srcStrLengthNL) {
|
|
// finalStrLength >= srcStrLength
|
|
SVal sourceInResult = svalBuilder.evalBinOpNN(state, BO_GE,
|
|
*finalStrLengthNL,
|
|
*srcStrLengthNL,
|
|
cmpTy);
|
|
state = state->assume(cast<DefinedOrUnknownSVal>(sourceInResult),
|
|
true);
|
|
if (!state)
|
|
return;
|
|
}
|
|
|
|
if (dstStrLengthNL) {
|
|
// finalStrLength >= dstStrLength
|
|
SVal destInResult = svalBuilder.evalBinOpNN(state, BO_GE,
|
|
*finalStrLengthNL,
|
|
*dstStrLengthNL,
|
|
cmpTy);
|
|
state = state->assume(cast<DefinedOrUnknownSVal>(destInResult),
|
|
true);
|
|
if (!state)
|
|
return;
|
|
}
|
|
}
|
|
}
|
|
|
|
} else {
|
|
// Otherwise, this is a copy-over function (strcpy, strncpy, ...), and
|
|
// the final string length will match the input string length.
|
|
finalStrLength = amountCopied;
|
|
}
|
|
|
|
// The final result of the function will either be a pointer past the last
|
|
// copied element, or a pointer to the start of the destination buffer.
|
|
SVal Result = (returnEnd ? UnknownVal() : DstVal);
|
|
|
|
assert(state);
|
|
|
|
// If the destination is a MemRegion, try to check for a buffer overflow and
|
|
// record the new string length.
|
|
if (loc::MemRegionVal *dstRegVal = dyn_cast<loc::MemRegionVal>(&DstVal)) {
|
|
// If the final length is known, we can check for an overflow.
|
|
if (NonLoc *knownStrLength = dyn_cast<NonLoc>(&finalStrLength)) {
|
|
SVal lastElement = svalBuilder.evalBinOpLN(state, BO_Add, *dstRegVal,
|
|
*knownStrLength,
|
|
Dst->getType());
|
|
|
|
state = CheckLocation(C, state, Dst, lastElement, /* IsDst = */ true);
|
|
if (!state)
|
|
return;
|
|
|
|
// If this is a stpcpy-style copy, the last element is the return value.
|
|
if (returnEnd)
|
|
Result = lastElement;
|
|
}
|
|
|
|
// Invalidate the destination. This must happen before we set the C string
|
|
// length because invalidation will clear the length.
|
|
// FIXME: Even if we can't perfectly model the copy, we should see if we
|
|
// can use LazyCompoundVals to copy the source values into the destination.
|
|
// This would probably remove any existing bindings past the end of the
|
|
// string, but that's still an improvement over blank invalidation.
|
|
state = InvalidateBuffer(C, state, Dst, *dstRegVal);
|
|
|
|
// Set the C string length of the destination.
|
|
state = setCStringLength(state, dstRegVal->getRegion(), finalStrLength);
|
|
}
|
|
|
|
assert(state);
|
|
|
|
// If this is a stpcpy-style copy, but we were unable to check for a buffer
|
|
// overflow, we still need a result. Conjure a return value.
|
|
if (returnEnd && Result.isUnknown()) {
|
|
unsigned Count = C.getNodeBuilder().getCurrentBlockCount();
|
|
Result = svalBuilder.getConjuredSymbolVal(NULL, CE, Count);
|
|
}
|
|
|
|
// Set the return value.
|
|
state = state->BindExpr(CE, Result);
|
|
C.addTransition(state);
|
|
}
|
|
|
|
void CStringChecker::evalStrcmp(CheckerContext &C, const CallExpr *CE) const {
|
|
//int strcmp(const char *restrict s1, const char *restrict s2);
|
|
evalStrcmpCommon(C, CE, /* isBounded = */ false, /* ignoreCase = */ false);
|
|
}
|
|
|
|
void CStringChecker::evalStrncmp(CheckerContext &C, const CallExpr *CE) const {
|
|
//int strncmp(const char *restrict s1, const char *restrict s2, size_t n);
|
|
evalStrcmpCommon(C, CE, /* isBounded = */ true, /* ignoreCase = */ false);
|
|
}
|
|
|
|
void CStringChecker::evalStrcasecmp(CheckerContext &C,
|
|
const CallExpr *CE) const {
|
|
//int strcasecmp(const char *restrict s1, const char *restrict s2);
|
|
evalStrcmpCommon(C, CE, /* isBounded = */ false, /* ignoreCase = */ true);
|
|
}
|
|
|
|
void CStringChecker::evalStrncasecmp(CheckerContext &C,
|
|
const CallExpr *CE) const {
|
|
//int strncasecmp(const char *restrict s1, const char *restrict s2, size_t n);
|
|
evalStrcmpCommon(C, CE, /* isBounded = */ true, /* ignoreCase = */ true);
|
|
}
|
|
|
|
void CStringChecker::evalStrcmpCommon(CheckerContext &C, const CallExpr *CE,
|
|
bool isBounded, bool ignoreCase) const {
|
|
const GRState *state = C.getState();
|
|
|
|
// Check that the first string is non-null
|
|
const Expr *s1 = CE->getArg(0);
|
|
SVal s1Val = state->getSVal(s1);
|
|
state = checkNonNull(C, state, s1, s1Val);
|
|
if (!state)
|
|
return;
|
|
|
|
// Check that the second string is non-null.
|
|
const Expr *s2 = CE->getArg(1);
|
|
SVal s2Val = state->getSVal(s2);
|
|
state = checkNonNull(C, state, s2, s2Val);
|
|
if (!state)
|
|
return;
|
|
|
|
// Get the string length of the first string or give up.
|
|
SVal s1Length = getCStringLength(C, state, s1, s1Val);
|
|
if (s1Length.isUndef())
|
|
return;
|
|
|
|
// Get the string length of the second string or give up.
|
|
SVal s2Length = getCStringLength(C, state, s2, s2Val);
|
|
if (s2Length.isUndef())
|
|
return;
|
|
|
|
// Get the string literal of the first string.
|
|
const StringLiteral *s1StrLiteral = getCStringLiteral(C, state, s1, s1Val);
|
|
if (!s1StrLiteral)
|
|
return;
|
|
llvm::StringRef s1StrRef = s1StrLiteral->getString();
|
|
|
|
// Get the string literal of the second string.
|
|
const StringLiteral *s2StrLiteral = getCStringLiteral(C, state, s2, s2Val);
|
|
if (!s2StrLiteral)
|
|
return;
|
|
llvm::StringRef s2StrRef = s2StrLiteral->getString();
|
|
|
|
int result;
|
|
if (isBounded) {
|
|
// Get the max number of characters to compare.
|
|
const Expr *lenExpr = CE->getArg(2);
|
|
SVal lenVal = state->getSVal(lenExpr);
|
|
|
|
// Dynamically cast the length to a ConcreteInt. If it is not a ConcreteInt
|
|
// then give up, otherwise get the value and use it as the bounds.
|
|
nonloc::ConcreteInt *CI = dyn_cast<nonloc::ConcreteInt>(&lenVal);
|
|
if (!CI)
|
|
return;
|
|
llvm::APSInt lenInt(CI->getValue());
|
|
|
|
// Create substrings of each to compare the prefix.
|
|
s1StrRef = s1StrRef.substr(0, (size_t)lenInt.getLimitedValue());
|
|
s2StrRef = s2StrRef.substr(0, (size_t)lenInt.getLimitedValue());
|
|
}
|
|
|
|
if (ignoreCase) {
|
|
// Compare string 1 to string 2 the same way strcasecmp() does.
|
|
result = s1StrRef.compare_lower(s2StrRef);
|
|
} else {
|
|
// Compare string 1 to string 2 the same way strcmp() does.
|
|
result = s1StrRef.compare(s2StrRef);
|
|
}
|
|
|
|
// Build the SVal of the comparison to bind the return value.
|
|
SValBuilder &svalBuilder = C.getSValBuilder();
|
|
QualType intTy = svalBuilder.getContext().IntTy;
|
|
SVal resultVal = svalBuilder.makeIntVal(result, intTy);
|
|
|
|
// Bind the return value of the expression.
|
|
// Set the return value.
|
|
state = state->BindExpr(CE, resultVal);
|
|
C.addTransition(state);
|
|
}
|
|
|
|
//===----------------------------------------------------------------------===//
|
|
// The driver method, and other Checker callbacks.
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
bool CStringChecker::evalCall(const CallExpr *CE, CheckerContext &C) const {
|
|
// Get the callee. All the functions we care about are C functions
|
|
// with simple identifiers.
|
|
const GRState *state = C.getState();
|
|
const Expr *Callee = CE->getCallee();
|
|
const FunctionDecl *FD = state->getSVal(Callee).getAsFunctionDecl();
|
|
|
|
if (!FD)
|
|
return false;
|
|
|
|
// Get the name of the callee. If it's a builtin, strip off the prefix.
|
|
IdentifierInfo *II = FD->getIdentifier();
|
|
if (!II) // if no identifier, not a simple C function
|
|
return false;
|
|
llvm::StringRef Name = II->getName();
|
|
if (Name.startswith("__builtin_"))
|
|
Name = Name.substr(10);
|
|
|
|
FnCheck evalFunction = llvm::StringSwitch<FnCheck>(Name)
|
|
.Cases("memcpy", "__memcpy_chk", &CStringChecker::evalMemcpy)
|
|
.Cases("mempcpy", "__mempcpy_chk", &CStringChecker::evalMempcpy)
|
|
.Cases("memcmp", "bcmp", &CStringChecker::evalMemcmp)
|
|
.Cases("memmove", "__memmove_chk", &CStringChecker::evalMemmove)
|
|
.Cases("strcpy", "__strcpy_chk", &CStringChecker::evalStrcpy)
|
|
//.Cases("strncpy", "__strncpy_chk", &CStringChecker::evalStrncpy)
|
|
.Cases("stpcpy", "__stpcpy_chk", &CStringChecker::evalStpcpy)
|
|
.Cases("strcat", "__strcat_chk", &CStringChecker::evalStrcat)
|
|
.Cases("strncat", "__strncat_chk", &CStringChecker::evalStrncat)
|
|
.Case("strlen", &CStringChecker::evalstrLength)
|
|
.Case("strnlen", &CStringChecker::evalstrnLength)
|
|
.Case("strcmp", &CStringChecker::evalStrcmp)
|
|
.Case("strncmp", &CStringChecker::evalStrncmp)
|
|
.Case("strcasecmp", &CStringChecker::evalStrcasecmp)
|
|
.Case("strncasecmp", &CStringChecker::evalStrncasecmp)
|
|
.Case("bcopy", &CStringChecker::evalBcopy)
|
|
.Default(NULL);
|
|
|
|
// If the callee isn't a string function, let another checker handle it.
|
|
if (!evalFunction)
|
|
return false;
|
|
|
|
// Check and evaluate the call.
|
|
(this->*evalFunction)(C, CE);
|
|
return true;
|
|
}
|
|
|
|
void CStringChecker::checkPreStmt(const DeclStmt *DS, CheckerContext &C) const {
|
|
// Record string length for char a[] = "abc";
|
|
const GRState *state = C.getState();
|
|
|
|
for (DeclStmt::const_decl_iterator I = DS->decl_begin(), E = DS->decl_end();
|
|
I != E; ++I) {
|
|
const VarDecl *D = dyn_cast<VarDecl>(*I);
|
|
if (!D)
|
|
continue;
|
|
|
|
// FIXME: Handle array fields of structs.
|
|
if (!D->getType()->isArrayType())
|
|
continue;
|
|
|
|
const Expr *Init = D->getInit();
|
|
if (!Init)
|
|
continue;
|
|
if (!isa<StringLiteral>(Init))
|
|
continue;
|
|
|
|
Loc VarLoc = state->getLValue(D, C.getPredecessor()->getLocationContext());
|
|
const MemRegion *MR = VarLoc.getAsRegion();
|
|
if (!MR)
|
|
continue;
|
|
|
|
SVal StrVal = state->getSVal(Init);
|
|
assert(StrVal.isValid() && "Initializer string is unknown or undefined");
|
|
DefinedOrUnknownSVal strLength
|
|
= cast<DefinedOrUnknownSVal>(getCStringLength(C, state, Init, StrVal));
|
|
|
|
state = state->set<CStringLength>(MR, strLength);
|
|
}
|
|
|
|
C.addTransition(state);
|
|
}
|
|
|
|
bool CStringChecker::wantsRegionChangeUpdate(const GRState *state) const {
|
|
CStringLength::EntryMap Entries = state->get<CStringLength>();
|
|
return !Entries.isEmpty();
|
|
}
|
|
|
|
const GRState *
|
|
CStringChecker::checkRegionChanges(const GRState *state,
|
|
const StoreManager::InvalidatedSymbols *,
|
|
const MemRegion * const *Begin,
|
|
const MemRegion * const *End) const {
|
|
CStringLength::EntryMap Entries = state->get<CStringLength>();
|
|
if (Entries.isEmpty())
|
|
return state;
|
|
|
|
llvm::SmallPtrSet<const MemRegion *, 8> Invalidated;
|
|
llvm::SmallPtrSet<const MemRegion *, 32> SuperRegions;
|
|
|
|
// First build sets for the changed regions and their super-regions.
|
|
for ( ; Begin != End; ++Begin) {
|
|
const MemRegion *MR = *Begin;
|
|
Invalidated.insert(MR);
|
|
|
|
SuperRegions.insert(MR);
|
|
while (const SubRegion *SR = dyn_cast<SubRegion>(MR)) {
|
|
MR = SR->getSuperRegion();
|
|
SuperRegions.insert(MR);
|
|
}
|
|
}
|
|
|
|
CStringLength::EntryMap::Factory &F = state->get_context<CStringLength>();
|
|
|
|
// Then loop over the entries in the current state.
|
|
for (CStringLength::EntryMap::iterator I = Entries.begin(),
|
|
E = Entries.end(); I != E; ++I) {
|
|
const MemRegion *MR = I.getKey();
|
|
|
|
// Is this entry for a super-region of a changed region?
|
|
if (SuperRegions.count(MR)) {
|
|
Entries = F.remove(Entries, MR);
|
|
continue;
|
|
}
|
|
|
|
// Is this entry for a sub-region of a changed region?
|
|
const MemRegion *Super = MR;
|
|
while (const SubRegion *SR = dyn_cast<SubRegion>(Super)) {
|
|
Super = SR->getSuperRegion();
|
|
if (Invalidated.count(Super)) {
|
|
Entries = F.remove(Entries, MR);
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
|
|
return state->set<CStringLength>(Entries);
|
|
}
|
|
|
|
void CStringChecker::checkLiveSymbols(const GRState *state,
|
|
SymbolReaper &SR) const {
|
|
// Mark all symbols in our string length map as valid.
|
|
CStringLength::EntryMap Entries = state->get<CStringLength>();
|
|
|
|
for (CStringLength::EntryMap::iterator I = Entries.begin(), E = Entries.end();
|
|
I != E; ++I) {
|
|
SVal Len = I.getData();
|
|
|
|
for (SVal::symbol_iterator si = Len.symbol_begin(), se = Len.symbol_end();
|
|
si != se; ++si)
|
|
SR.markInUse(*si);
|
|
}
|
|
}
|
|
|
|
void CStringChecker::checkDeadSymbols(SymbolReaper &SR,
|
|
CheckerContext &C) const {
|
|
if (!SR.hasDeadSymbols())
|
|
return;
|
|
|
|
const GRState *state = C.getState();
|
|
CStringLength::EntryMap Entries = state->get<CStringLength>();
|
|
if (Entries.isEmpty())
|
|
return;
|
|
|
|
CStringLength::EntryMap::Factory &F = state->get_context<CStringLength>();
|
|
for (CStringLength::EntryMap::iterator I = Entries.begin(), E = Entries.end();
|
|
I != E; ++I) {
|
|
SVal Len = I.getData();
|
|
if (SymbolRef Sym = Len.getAsSymbol()) {
|
|
if (SR.isDead(Sym))
|
|
Entries = F.remove(Entries, I.getKey());
|
|
}
|
|
}
|
|
|
|
state = state->set<CStringLength>(Entries);
|
|
C.generateNode(state);
|
|
}
|
|
|
|
void ento::registerCStringChecker(CheckerManager &mgr) {
|
|
mgr.registerChecker<CStringChecker>();
|
|
}
|