From 3dbc7596a3b7aca37e80f76288d3ab761ddd247a Mon Sep 17 00:00:00 2001 From: Volker Hilsheimer Date: Tue, 8 Oct 2019 10:56:44 +0200 Subject: Drag'n'Drop: fix crash when widgets are destroyed during event handling Widgets might be destroyed when handling a dragMoveEvent, in which case the following code will operate on dangling pointers or null pointers. Use a QPointer to watch for the original event receiver to disappear, and add the necessary checks for the objects we deliver events to being null. Change-Id: I4ca2f182540ae21113f4bea4e5c569e983cc58bf Fixes: QTBUG-78907 Reviewed-by: Gatis Paeglis --- src/widgets/kernel/qwidgetwindow.cpp | 22 +++++++++++++--------- 1 file changed, 13 insertions(+), 9 deletions(-) (limited to 'src/widgets/kernel') diff --git a/src/widgets/kernel/qwidgetwindow.cpp b/src/widgets/kernel/qwidgetwindow.cpp index fbc71cd0ea..aad505ed29 100644 --- a/src/widgets/kernel/qwidgetwindow.cpp +++ b/src/widgets/kernel/qwidgetwindow.cpp @@ -885,7 +885,7 @@ void QWidgetWindow::handleDragEnterEvent(QDragEnterEvent *event, QWidget *widget void QWidgetWindow::handleDragMoveEvent(QDragMoveEvent *event) { - auto *widget = findDnDTarget(m_widget, event->pos()); + QPointer widget = findDnDTarget(m_widget, event->pos()); if (!widget) { event->ignore(); if (m_dragTarget) { // Send DragLeave to previous @@ -908,14 +908,18 @@ void QWidgetWindow::handleDragMoveEvent(QDragMoveEvent *event) QGuiApplication::forwardEvent(m_dragTarget, &leaveEvent, event); m_dragTarget = nullptr; } - // Send DragEnter to new widget. - handleDragEnterEvent(static_cast(event), widget); - // Handling 'DragEnter' should suffice for the application. - translated.setDropAction(event->dropAction()); - translated.setAccepted(event->isAccepted()); - // The drag enter event is always immediately followed by a drag move event, - // see QDragEnterEvent documentation. - QGuiApplication::forwardEvent(m_dragTarget, &translated, event); + // widget might have been deleted when handling the leaveEvent + if (widget) { + // Send DragEnter to new widget. + handleDragEnterEvent(static_cast(event), widget); + // Handling 'DragEnter' should suffice for the application. + translated.setDropAction(event->dropAction()); + translated.setAccepted(event->isAccepted()); + // The drag enter event is always immediately followed by a drag move event, + // see QDragEnterEvent documentation. + if (m_dragTarget) + QGuiApplication::forwardEvent(m_dragTarget, &translated, event); + } } event->setAccepted(translated.isAccepted()); event->setDropAction(translated.dropAction()); -- cgit v1.2.3