QWindowsScreenManager::removeScreen() read an element from m_screens and removed it. If the removed screen was not the primary screen, QWindowSystemInterface::flushWindowSystemEvents() is called. When removeScreen() is called from handleScreenChanges() in the same class, flushing window events can lead to a re-entry. That is e.g. the case when a RDP connection is closed and the server removes the virtual screen. QWindowScreenManager::removeScreen() removes the platform screen only at the very end, which means that m_screens contains a stale pointer. The re-entry can therefore crash with a double delete. Take the platform screen at the beginning of the method, to make it safe for re-entry. Fixes: QTBUG-135337 Pick-to: 6.10 6.9 6.8 6.5 Change-Id: Id18a6fb3e72922bcdb62c9e79857b6bb713c0c1b Reviewed-by: Tor Arne Vestbø <tor.arne.vestbo@qt.io> Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io> Reviewed-by: Wladimir Leuschner <wladimir.leuschner@qt.io>