From 7f9253defd2e90f900d963c6d248a2a0bdaca1a8 Mon Sep 17 00:00:00 2001 From: Volker Hilsheimer Date: Tue, 16 Aug 2022 15:32:58 +0200 Subject: [PATCH] Don't access QObjectPrivate::declarativeData unguarded MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit The QObjectPrivate::declarativeData member is stored in a union with currentChildBeingDeleted. The QObject destructor always sets the currentChildBeingDeleted member of the union. It also sets the isDeletingChildren bool, which is the only way to find out which union member we can safely access. While the QObject destructor is deleting children and isDeletingChildren is set, we must not access the declarativeData member of the union. Add a test case that initializes the function pointers for the declarative handlers and constructs a situation where an object emits a signal while it is destroying children. Fixes: QTBUG-105286 Pick-to: 6.4 6.3 6.3.2 6.2 5.15 Change-Id: Iea5ba2f7843b6926a8d157be166e6044d98d6c02 Reviewed-by: Qt CI Bot Reviewed-by: Mårten Nordheim (cherry picked from commit 3be99799a675a631c67e05897383af9abbc377b3) --- src/corelib/kernel/qobject.cpp | 4 +- src/corelib/kernel/qobject_p.h | 2 +- .../corelib/kernel/qobject/tst_qobject.cpp | 77 +++++++++++++++++++ 3 files changed, 80 insertions(+), 3 deletions(-) diff --git a/src/corelib/kernel/qobject.cpp b/src/corelib/kernel/qobject.cpp index 0124f88abd..1f3843669b 100644 --- a/src/corelib/kernel/qobject.cpp +++ b/src/corelib/kernel/qobject.cpp @@ -992,7 +992,7 @@ QObject::~QObject() emit destroyed(this); } - if (d->declarativeData) { + if (!d->isDeletingChildren && d->declarativeData) { if (static_cast(d->declarativeData)->ownedByQml1) { if (QAbstractDeclarativeData::destroyed_qml1) QAbstractDeclarativeData::destroyed_qml1(d->declarativeData, this); @@ -2583,7 +2583,7 @@ int QObject::receivers(const char *signal) const if (!d->isSignalConnected(signal_index)) return receivers; - if (d->declarativeData && QAbstractDeclarativeData::receivers) { + if (!d->isDeletingChildren && d->declarativeData && QAbstractDeclarativeData::receivers) { receivers += QAbstractDeclarativeData::receivers(d->declarativeData, this, signal_index); } diff --git a/src/corelib/kernel/qobject_p.h b/src/corelib/kernel/qobject_p.h index 66c19d174e..46dcb93521 100644 --- a/src/corelib/kernel/qobject_p.h +++ b/src/corelib/kernel/qobject_p.h @@ -428,7 +428,7 @@ inline void QObjectPrivate::checkForIncompatibleLibraryVersion(int version) cons inline bool QObjectPrivate::isDeclarativeSignalConnected(uint signal_index) const { - return declarativeData && QAbstractDeclarativeData::isSignalConnected + return !isDeletingChildren && declarativeData && QAbstractDeclarativeData::isSignalConnected && QAbstractDeclarativeData::isSignalConnected(declarativeData, q_func(), signal_index); } diff --git a/tests/auto/corelib/kernel/qobject/tst_qobject.cpp b/tests/auto/corelib/kernel/qobject/tst_qobject.cpp index 9bd66c0835..ed4a0bae5d 100644 --- a/tests/auto/corelib/kernel/qobject/tst_qobject.cpp +++ b/tests/auto/corelib/kernel/qobject/tst_qobject.cpp @@ -158,6 +158,7 @@ private slots: void nullReceiver(); void functorReferencesConnection(); void disconnectDisconnects(); + void declarativeData(); }; struct QObjectCreatedOnShutdown @@ -7679,5 +7680,81 @@ void tst_QObject::disconnectDisconnects() Q_STATIC_ASSERT(QtPrivate::HasQ_OBJECT_Macro::Value); Q_STATIC_ASSERT(!QtPrivate::HasQ_OBJECT_Macro::Value); +#ifdef QT_BUILD_INTERNAL +/* + Since QObjectPrivate stores the declarativeData pointer in a union with the pointer + to the currently destroyed child, calls to the QtDeclarative handlers need to be + correctly guarded. QTBUG-105286 +*/ +namespace QtDeclarative { +static QAbstractDeclarativeData *theData; + +static void destroyed(QAbstractDeclarativeData *data, QObject *) +{ + QCOMPARE(data, theData); +} +static void signalEmitted(QAbstractDeclarativeData *data, QObject *, int, void **) +{ + QCOMPARE(data, theData); +} +// we can't use QCOMPARE in the next two functions, as they don't return void +static int receivers(QAbstractDeclarativeData *data, const QObject *, int) +{ + QTest::qCompare(data, theData, "data", "theData", __FILE__, __LINE__); + return 0; +} +static bool isSignalConnected(QAbstractDeclarativeData *data, const QObject *, int) +{ + QTest::qCompare(data, theData, "data", "theData", __FILE__, __LINE__); + return true; +} + +class Object : public QObject +{ + Q_OBJECT +public: + using QObject::QObject; + ~Object() + { + if (Object *p = static_cast(parent())) + p->emitSignal(); + } + + void emitSignal() + { + emit theSignal(); + } + +signals: + void theSignal(); +}; + +} +#endif + +void tst_QObject::declarativeData() +{ +#ifdef QT_BUILD_INTERNAL + QScopedValueRollback destroyed(QAbstractDeclarativeData::destroyed, + QtDeclarative::destroyed); + QScopedValueRollback signalEmitted(QAbstractDeclarativeData::signalEmitted, + QtDeclarative::signalEmitted); + QScopedValueRollback receivers(QAbstractDeclarativeData::receivers, + QtDeclarative::receivers); + QScopedValueRollback isSignalConnected(QAbstractDeclarativeData::isSignalConnected, + QtDeclarative::isSignalConnected); + + QtDeclarative::Object p; + QObjectPrivate *priv = QObjectPrivate::get(&p); + priv->declarativeData = QtDeclarative::theData = new QAbstractDeclarativeData; + + connect(&p, &QtDeclarative::Object::theSignal, &p, []{ + }); + + QtDeclarative::Object *child = new QtDeclarative::Object; + child->setParent(&p); +#endif +} + QTEST_MAIN(tst_QObject) #include "tst_qobject.moc" -- GitLab