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@@ -18,6 +18,7 @@
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#include "clang/StaticAnalyzer/Core/BugReporter/BugType.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/CallEvent.h"
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#include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
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#include "clang/StaticAnalyzer/Core/PathSensitive/ProgramState.h"
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#include "llvm/ADT/SmallString.h"
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@@ -26,85 +27,131 @@ using namespace clang;
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using namespace ento;
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namespace {
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-class StackAddrEscapeChecker : public Checker< check::PreStmt<ReturnStmt>,
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- check::EndFunction > {
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+class StackAddrEscapeChecker
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+ : public Checker<check::PreCall, check::PreStmt<ReturnStmt>,
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+ check::EndFunction> {
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+ mutable IdentifierInfo *dispatch_semaphore_tII;
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mutable std::unique_ptr<BuiltinBug> BT_stackleak;
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mutable std::unique_ptr<BuiltinBug> BT_returnstack;
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+ mutable std::unique_ptr<BuiltinBug> BT_capturedstackasync;
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+ mutable std::unique_ptr<BuiltinBug> BT_capturedstackret;
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public:
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+ void checkPreCall(const CallEvent &Call, CheckerContext &C) const;
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void checkPreStmt(const ReturnStmt *RS, CheckerContext &C) const;
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void checkEndFunction(CheckerContext &Ctx) const;
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+
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private:
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+ void checkReturnedBlockCaptures(const BlockDataRegion &B,
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+ CheckerContext &C) const;
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+ void checkAsyncExecutedBlockCaptures(const BlockDataRegion &B,
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+ CheckerContext &C) const;
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void EmitStackError(CheckerContext &C, const MemRegion *R,
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const Expr *RetE) const;
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+ bool isSemaphoreCaptured(const BlockDecl &B) const;
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static SourceRange genName(raw_ostream &os, const MemRegion *R,
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ASTContext &Ctx);
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+ static SmallVector<const MemRegion *, 4>
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+ getCapturedStackRegions(const BlockDataRegion &B, CheckerContext &C);
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+ static bool isArcManagedBlock(const MemRegion *R, CheckerContext &C);
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+ static bool isNotInCurrentFrame(const MemRegion *R, CheckerContext &C);
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};
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-}
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+} // namespace
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SourceRange StackAddrEscapeChecker::genName(raw_ostream &os, const MemRegion *R,
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ASTContext &Ctx) {
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- // Get the base region, stripping away fields and elements.
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+ // Get the base region, stripping away fields and elements.
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R = R->getBaseRegion();
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SourceManager &SM = Ctx.getSourceManager();
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SourceRange range;
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os << "Address of ";
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// Check if the region is a compound literal.
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- if (const CompoundLiteralRegion* CR = dyn_cast<CompoundLiteralRegion>(R)) {
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+ if (const auto *CR = dyn_cast<CompoundLiteralRegion>(R)) {
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const CompoundLiteralExpr *CL = CR->getLiteralExpr();
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os << "stack memory associated with a compound literal "
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"declared on line "
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- << SM.getExpansionLineNumber(CL->getLocStart())
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- << " returned to caller";
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+ << SM.getExpansionLineNumber(CL->getLocStart()) << " returned to caller";
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range = CL->getSourceRange();
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- }
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- else if (const AllocaRegion* AR = dyn_cast<AllocaRegion>(R)) {
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+ } else if (const auto *AR = dyn_cast<AllocaRegion>(R)) {
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const Expr *ARE = AR->getExpr();
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SourceLocation L = ARE->getLocStart();
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range = ARE->getSourceRange();
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os << "stack memory allocated by call to alloca() on line "
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<< SM.getExpansionLineNumber(L);
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- }
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- else if (const BlockDataRegion *BR = dyn_cast<BlockDataRegion>(R)) {
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+ } else if (const auto *BR = dyn_cast<BlockDataRegion>(R)) {
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const BlockDecl *BD = BR->getCodeRegion()->getDecl();
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SourceLocation L = BD->getLocStart();
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range = BD->getSourceRange();
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os << "stack-allocated block declared on line "
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<< SM.getExpansionLineNumber(L);
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- }
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- else if (const VarRegion *VR = dyn_cast<VarRegion>(R)) {
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- os << "stack memory associated with local variable '"
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- << VR->getString() << '\'';
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+ } else if (const auto *VR = dyn_cast<VarRegion>(R)) {
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+ os << "stack memory associated with local variable '" << VR->getString()
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+ << '\'';
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range = VR->getDecl()->getSourceRange();
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- }
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- else if (const CXXTempObjectRegion *TOR = dyn_cast<CXXTempObjectRegion>(R)) {
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+ } else if (const auto *TOR = dyn_cast<CXXTempObjectRegion>(R)) {
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QualType Ty = TOR->getValueType().getLocalUnqualifiedType();
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os << "stack memory associated with temporary object of type '";
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Ty.print(os, Ctx.getPrintingPolicy());
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os << "'";
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range = TOR->getExpr()->getSourceRange();
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- }
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- else {
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+ } else {
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llvm_unreachable("Invalid region in ReturnStackAddressChecker.");
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}
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return range;
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}
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-void StackAddrEscapeChecker::EmitStackError(CheckerContext &C, const MemRegion *R,
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- const Expr *RetE) const {
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- ExplodedNode *N = C.generateErrorNode();
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+bool StackAddrEscapeChecker::isArcManagedBlock(const MemRegion *R,
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+ CheckerContext &C) {
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+ assert(R && "MemRegion should not be null");
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+ return C.getASTContext().getLangOpts().ObjCAutoRefCount &&
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+ isa<BlockDataRegion>(R);
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+}
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+
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+bool StackAddrEscapeChecker::isNotInCurrentFrame(const MemRegion *R,
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+ CheckerContext &C) {
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+ const StackSpaceRegion *S = cast<StackSpaceRegion>(R->getMemorySpace());
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+ return S->getStackFrame() != C.getLocationContext()->getCurrentStackFrame();
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+}
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+
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+bool StackAddrEscapeChecker::isSemaphoreCaptured(const BlockDecl &B) const {
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+ if (!dispatch_semaphore_tII)
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+ dispatch_semaphore_tII = &B.getASTContext().Idents.get("dispatch_semaphore_t");
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+ for (const auto &C : B.captures()) {
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+ const auto *T = C.getVariable()->getType()->getAs<TypedefType>();
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+ if (T && T->getDecl()->getIdentifier() == dispatch_semaphore_tII)
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+ return true;
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+ }
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+ return false;
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+}
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+
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+SmallVector<const MemRegion *, 4>
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+StackAddrEscapeChecker::getCapturedStackRegions(const BlockDataRegion &B,
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+ CheckerContext &C) {
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+ SmallVector<const MemRegion *, 4> Regions;
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+ BlockDataRegion::referenced_vars_iterator I = B.referenced_vars_begin();
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+ BlockDataRegion::referenced_vars_iterator E = B.referenced_vars_end();
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+ for (; I != E; ++I) {
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+ SVal Val = C.getState()->getSVal(I.getCapturedRegion());
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+ const MemRegion *Region = Val.getAsRegion();
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+ if (Region && isa<StackSpaceRegion>(Region->getMemorySpace()))
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+ Regions.push_back(Region);
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+ }
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+ return Regions;
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+}
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+void StackAddrEscapeChecker::EmitStackError(CheckerContext &C,
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+ const MemRegion *R,
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+ const Expr *RetE) const {
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+ ExplodedNode *N = C.generateNonFatalErrorNode();
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if (!N)
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return;
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-
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if (!BT_returnstack)
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- BT_returnstack.reset(
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- new BuiltinBug(this, "Return of address to stack-allocated memory"));
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-
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+ BT_returnstack = llvm::make_unique<BuiltinBug>(
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+ this, "Return of address to stack-allocated memory");
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// Generate a report for this bug.
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- SmallString<512> buf;
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+ SmallString<128> buf;
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llvm::raw_svector_ostream os(buf);
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SourceRange range = genName(os, R, C.getASTContext());
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os << " returned to caller";
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@@ -112,10 +159,82 @@ void StackAddrEscapeChecker::EmitStackError(CheckerContext &C, const MemRegion *
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report->addRange(RetE->getSourceRange());
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if (range.isValid())
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report->addRange(range);
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-
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C.emitReport(std::move(report));
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}
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+void StackAddrEscapeChecker::checkAsyncExecutedBlockCaptures(
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+ const BlockDataRegion &B, CheckerContext &C) const {
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+ // There is a not-too-uncommon idiom
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+ // where a block passed to dispatch_async captures a semaphore
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+ // and then the thread (which called dispatch_async) is blocked on waiting
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+ // for the completion of the execution of the block
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+ // via dispatch_semaphore_wait. To avoid false-positives (for now)
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+ // we ignore all the blocks which have captured
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+ // a variable of the type "dispatch_semaphore_t".
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+ if (isSemaphoreCaptured(*B.getDecl()))
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+ return;
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+ for (const MemRegion *Region : getCapturedStackRegions(B, C)) {
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+ // The block passed to dispatch_async may capture another block
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+ // created on the stack. However, there is no leak in this situaton,
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+ // no matter if ARC or no ARC is enabled:
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+ // dispatch_async copies the passed "outer" block (via Block_copy)
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+ // and if the block has captured another "inner" block,
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+ // the "inner" block will be copied as well.
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+ if (isa<BlockDataRegion>(Region))
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+ continue;
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+ ExplodedNode *N = C.generateNonFatalErrorNode();
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+ if (!N)
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+ continue;
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+ if (!BT_capturedstackasync)
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+ BT_capturedstackasync = llvm::make_unique<BuiltinBug>(
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+ this, "Address of stack-allocated memory is captured");
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+ SmallString<128> Buf;
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+ llvm::raw_svector_ostream Out(Buf);
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+ SourceRange Range = genName(Out, Region, C.getASTContext());
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+ Out << " is captured by an asynchronously-executed block";
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+ auto Report =
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+ llvm::make_unique<BugReport>(*BT_capturedstackasync, Out.str(), N);
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+ if (Range.isValid())
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+ Report->addRange(Range);
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+ C.emitReport(std::move(Report));
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+ }
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+}
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+
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+void StackAddrEscapeChecker::checkReturnedBlockCaptures(
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+ const BlockDataRegion &B, CheckerContext &C) const {
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+ for (const MemRegion *Region : getCapturedStackRegions(B, C)) {
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+ if (isArcManagedBlock(Region, C) || isNotInCurrentFrame(Region, C))
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+ continue;
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+ ExplodedNode *N = C.generateNonFatalErrorNode();
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+ if (!N)
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+ continue;
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+ if (!BT_capturedstackret)
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+ BT_capturedstackret = llvm::make_unique<BuiltinBug>(
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+ this, "Address of stack-allocated memory is captured");
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+ SmallString<128> Buf;
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+ llvm::raw_svector_ostream Out(Buf);
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+ SourceRange Range = genName(Out, Region, C.getASTContext());
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+ Out << " is captured by a returned block";
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+ auto Report =
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+ llvm::make_unique<BugReport>(*BT_capturedstackret, Out.str(), N);
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+ if (Range.isValid())
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+ Report->addRange(Range);
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+ C.emitReport(std::move(Report));
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+ }
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+}
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+
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+void StackAddrEscapeChecker::checkPreCall(const CallEvent &Call,
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+ CheckerContext &C) const {
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+ if (!Call.isGlobalCFunction("dispatch_after") &&
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+ !Call.isGlobalCFunction("dispatch_async"))
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+ return;
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+ for (unsigned Idx = 0, NumArgs = Call.getNumArgs(); Idx < NumArgs; ++Idx) {
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+ if (const BlockDataRegion *B = dyn_cast_or_null<BlockDataRegion>(
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+ Call.getArgSVal(Idx).getAsRegion()))
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+ checkAsyncExecutedBlockCaptures(*B, C);
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+ }
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+}
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+
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void StackAddrEscapeChecker::checkPreStmt(const ReturnStmt *RS,
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CheckerContext &C) const {
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@@ -127,25 +246,14 @@ void StackAddrEscapeChecker::checkPreStmt(const ReturnStmt *RS,
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const LocationContext *LCtx = C.getLocationContext();
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SVal V = C.getState()->getSVal(RetE, LCtx);
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const MemRegion *R = V.getAsRegion();
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-
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if (!R)
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return;
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- const StackSpaceRegion *SS =
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- dyn_cast_or_null<StackSpaceRegion>(R->getMemorySpace());
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+ if (const BlockDataRegion *B = dyn_cast<BlockDataRegion>(R))
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+ checkReturnedBlockCaptures(*B, C);
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- if (!SS)
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- return;
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-
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- // Return stack memory in an ancestor stack frame is fine.
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- const StackFrameContext *CurFrame = LCtx->getCurrentStackFrame();
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- const StackFrameContext *MemFrame = SS->getStackFrame();
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- if (MemFrame != CurFrame)
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- return;
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-
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- // Automatic reference counting automatically copies blocks.
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- if (C.getASTContext().getLangOpts().ObjCAutoRefCount &&
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- isa<BlockDataRegion>(R))
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+ if (!isa<StackSpaceRegion>(R->getMemorySpace()) ||
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+ isNotInCurrentFrame(R, C) || isArcManagedBlock(R, C))
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return;
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// Returning a record by value is fine. (In this case, the returned
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@@ -169,7 +277,7 @@ void StackAddrEscapeChecker::checkPreStmt(const ReturnStmt *RS,
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}
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void StackAddrEscapeChecker::checkEndFunction(CheckerContext &Ctx) const {
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- ProgramStateRef state = Ctx.getState();
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+ ProgramStateRef State = Ctx.getState();
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// Iterate over all bindings to global variables and see if it contains
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// a memory region in the stack space.
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@@ -177,82 +285,67 @@ void StackAddrEscapeChecker::checkEndFunction(CheckerContext &Ctx) const {
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private:
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CheckerContext &Ctx;
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const StackFrameContext *CurSFC;
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- public:
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- SmallVector<std::pair<const MemRegion*, const MemRegion*>, 10> V;
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-
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- CallBack(CheckerContext &CC) :
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- Ctx(CC),
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- CurSFC(CC.getLocationContext()->getCurrentStackFrame())
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- {}
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- bool HandleBinding(StoreManager &SMgr, Store store,
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- const MemRegion *region, SVal val) override {
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+ public:
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+ SmallVector<std::pair<const MemRegion *, const MemRegion *>, 10> V;
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- if (!isa<GlobalsSpaceRegion>(region->getMemorySpace()))
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- return true;
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+ CallBack(CheckerContext &CC)
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+ : Ctx(CC), CurSFC(CC.getLocationContext()->getCurrentStackFrame()) {}
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- const MemRegion *vR = val.getAsRegion();
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- if (!vR)
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- return true;
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+ bool HandleBinding(StoreManager &SMgr, Store S, const MemRegion *Region,
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+ SVal Val) override {
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- // Under automated retain release, it is okay to assign a block
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- // directly to a global variable.
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- if (Ctx.getASTContext().getLangOpts().ObjCAutoRefCount &&
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- isa<BlockDataRegion>(vR))
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+ if (!isa<GlobalsSpaceRegion>(Region->getMemorySpace()))
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return true;
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-
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- if (const StackSpaceRegion *SSR =
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- dyn_cast<StackSpaceRegion>(vR->getMemorySpace())) {
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- // If the global variable holds a location in the current stack frame,
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- // record the binding to emit a warning.
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- if (SSR->getStackFrame() == CurSFC)
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- V.push_back(std::make_pair(region, vR));
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- }
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-
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+ const MemRegion *VR = Val.getAsRegion();
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+ if (VR && isa<StackSpaceRegion>(VR->getMemorySpace()) &&
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+ !isArcManagedBlock(VR, Ctx) && !isNotInCurrentFrame(VR, Ctx))
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+ V.emplace_back(Region, VR);
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return true;
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}
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};
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- CallBack cb(Ctx);
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- state->getStateManager().getStoreManager().iterBindings(state->getStore(),cb);
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+ CallBack Cb(Ctx);
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+ State->getStateManager().getStoreManager().iterBindings(State->getStore(),
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+ Cb);
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- if (cb.V.empty())
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+ if (Cb.V.empty())
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return;
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// Generate an error node.
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- ExplodedNode *N = Ctx.generateNonFatalErrorNode(state);
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+ ExplodedNode *N = Ctx.generateNonFatalErrorNode(State);
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if (!N)
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return;
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if (!BT_stackleak)
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- BT_stackleak.reset(
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- new BuiltinBug(this, "Stack address stored into global variable",
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- "Stack address was saved into a global variable. "
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- "This is dangerous because the address will become "
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- "invalid after returning from the function"));
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+ BT_stackleak = llvm::make_unique<BuiltinBug>(
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+ this, "Stack address stored into global variable",
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+ "Stack address was saved into a global variable. "
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+ "This is dangerous because the address will become "
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+ "invalid after returning from the function");
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- for (unsigned i = 0, e = cb.V.size(); i != e; ++i) {
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+ for (const auto &P : Cb.V) {
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// Generate a report for this bug.
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- SmallString<512> buf;
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- llvm::raw_svector_ostream os(buf);
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- SourceRange range = genName(os, cb.V[i].second, Ctx.getASTContext());
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- os << " is still referred to by the ";
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|
- if (isa<StaticGlobalSpaceRegion>(cb.V[i].first->getMemorySpace()))
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|
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- os << "static";
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|
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+ SmallString<128> Buf;
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|
|
+ llvm::raw_svector_ostream Out(Buf);
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|
|
+ SourceRange Range = genName(Out, P.second, Ctx.getASTContext());
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|
|
+ Out << " is still referred to by the ";
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|
|
+ if (isa<StaticGlobalSpaceRegion>(P.first->getMemorySpace()))
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|
|
+ Out << "static";
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|
else
|
|
|
- os << "global";
|
|
|
- os << " variable '";
|
|
|
- const VarRegion *VR = cast<VarRegion>(cb.V[i].first->getBaseRegion());
|
|
|
- os << *VR->getDecl()
|
|
|
- << "' upon returning to the caller. This will be a dangling reference";
|
|
|
- auto report = llvm::make_unique<BugReport>(*BT_stackleak, os.str(), N);
|
|
|
- if (range.isValid())
|
|
|
- report->addRange(range);
|
|
|
-
|
|
|
- Ctx.emitReport(std::move(report));
|
|
|
+ Out << "global";
|
|
|
+ Out << " variable '";
|
|
|
+ const VarRegion *VR = cast<VarRegion>(P.first->getBaseRegion());
|
|
|
+ Out << *VR->getDecl()
|
|
|
+ << "' upon returning to the caller. This will be a dangling reference";
|
|
|
+ auto Report = llvm::make_unique<BugReport>(*BT_stackleak, Out.str(), N);
|
|
|
+ if (Range.isValid())
|
|
|
+ Report->addRange(Range);
|
|
|
+
|
|
|
+ Ctx.emitReport(std::move(Report));
|
|
|
}
|
|
|
}
|
|
|
|
|
|
-void ento::registerStackAddrEscapeChecker(CheckerManager &mgr) {
|
|
|
- mgr.registerChecker<StackAddrEscapeChecker>();
|
|
|
+void ento::registerStackAddrEscapeChecker(CheckerManager &Mgr) {
|
|
|
+ Mgr.registerChecker<StackAddrEscapeChecker>();
|
|
|
}
|