Bug 348597

Application: kcmshell5 (5.2.2)

Qt Version: 5.4.1
Operating System: Linux 3.19.0-18-generic x86_64
Distribution: Ubuntu 15.04

-- Information about the crash:
- What I was doing when the application crashed:
If I switch from two displays (external DVI display + laptop screen) to only the laptop screen using the "Display Configuration" utility then almost all the time a sigsev occurs.

- Unusual behavior I noticed:
KDE does not start any more without the second display attached. Can currently only use laptop in the docing station. After login the KDE loader(?) (progress bar) stuck at ~80%.

The crash can be reproduced every time.

-- Backtrace:
Application: KDE Control Module (kcmshell5), signal: Segmentation fault
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
[Current thread is 1 (Thread 0x7f2b27de5800 (LWP 5313))]

Thread 3 (Thread 0x7f2b13660700 (LWP 5314)):
#0  0x00007f2b278d18dd in poll () at ../sysdeps/unix/syscall-template.S:81
#1  0x00007f2b1ffbdb72 in ?? () from /usr/lib/x86_64-linux-gnu/libxcb.so.1
#2  0x00007f2b1ffbf64f in xcb_wait_for_event () from /usr/lib/x86_64-linux-gnu/libxcb.so.1
#3  0x00007f2b15584099 in QXcbEventReader::run (this=0x1e30970) at qxcbconnection.cpp:1105
#4  0x00007f2b25954b0e in QThreadPrivate::start (arg=0x1e30970) at thread/qthread_unix.cpp:337
#5  0x00007f2b2538b6aa in start_thread (arg=0x7f2b13660700) at pthread_create.c:333
#6  0x00007f2b278dceed in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:109

Thread 2 (Thread 0x7f2b03fff700 (LWP 5318)):
#0  0x00007f2b278d18dd in poll () at ../sysdeps/unix/syscall-template.S:81
#1  0x00007f2b1f899ebc in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#2  0x00007f2b1f899fcc in g_main_context_iteration () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#3  0x00007f2b25bebc6c in QEventDispatcherGlib::processEvents (this=0x7f2afc0008c0, flags=...) at kernel/qeventdispatcher_glib.cpp:418
#4  0x00007f2b25b903e2 in QEventLoop::exec (this=this@entry=0x7f2b03ffeda0, flags=..., flags@entry=...) at kernel/qeventloop.cpp:204
#5  0x00007f2b2594fb44 in QThread::exec (this=<optimized out>) at thread/qthread.cpp:503
#6  0x00007f2b24d95f65 in ?? () from /usr/lib/x86_64-linux-gnu/libQt5Qml.so.5
#7  0x00007f2b25954b0e in QThreadPrivate::start (arg=0x23c8050) at thread/qthread_unix.cpp:337
#8  0x00007f2b2538b6aa in start_thread (arg=0x7f2b03fff700) at pthread_create.c:333
#9  0x00007f2b278dceed in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:109

Thread 1 (Thread 0x7f2b27de5800 (LWP 5313)):
[KCrash Handler]
#6  0x00007f2b115d0df4 in isEmpty (this=0x30) at /usr/include/x86_64-linux-gnu/qt5/QtCore/qstring.h:791
#7  KScreen::ConfigOperation::hasError (this=this@entry=0x289a700) at ../../src/configoperation.cpp:76
#8  0x00007f2b115d1026 in KScreen::ConfigOperation::exec (this=0x289a700) at ../../src/configoperation.cpp:109
#9  0x00007f2b1180433c in KCMKScreen::save (this=0x289a700) at ../../../kcm/src/kcm_kscreen.cpp:144
#10 0x00007f2b275b5077 in KCModuleProxy::save (this=this@entry=0x1edcc70) at ../../src/kcmoduleproxy.cpp:272
#11 0x00007f2b275b22f0 in KCMultiDialogPrivate::apply (this=<optimized out>) at ../../src/kcmultidialog.cpp:323
#12 0x00007f2b275b2695 in KCMultiDialog::qt_static_metacall (_o=0x289a700, _c=QMetaObject::ReadProperty, _id=1, _a=0x0) at ./moc_kcmultidialog.cpp:112
#13 0x00007f2b25bc39c9 in QMetaObject::activate (sender=sender@entry=0x1ea6bf0, signalOffset=<optimized out>, local_signal_index=local_signal_index@entry=2, argv=argv@entry=0x7fffdfb69820) at kernel/qobject.cpp:3716
#14 0x00007f2b25bc4057 in QMetaObject::activate (sender=sender@entry=0x1ea6bf0, m=m@entry=0x7f2b26489a60 <QAbstractButton::staticMetaObject>, local_signal_index=local_signal_index@entry=2, argv=argv@entry=0x7fffdfb69820) at kernel/qobject.cpp:3582
#15 0x00007f2b262fe012 in QAbstractButton::clicked (this=this@entry=0x1ea6bf0, _t1=false) at .moc/moc_qabstractbutton.cpp:298
#16 0x00007f2b2604b675 in QAbstractButtonPrivate::emitClicked (this=0x1eeca40) at widgets/qabstractbutton.cpp:534
#17 0x00007f2b2604c299 in QAbstractButtonPrivate::click (this=0x1eeca40) at widgets/qabstractbutton.cpp:527
#18 0x00007f2b2604c454 in QAbstractButton::mouseReleaseEvent (this=0x1ea6bf0, e=0x7fffdfb69ce0) at widgets/qabstractbutton.cpp:1132
#19 0x00007f2b25f931e8 in QWidget::event (this=0x1ea6bf0, event=0x7fffdfb69ce0) at kernel/qwidget.cpp:9022
#20 0x00007f2b25f4fb2c in QApplicationPrivate::notify_helper (this=0x1e19ec0, receiver=0x1ea6bf0, e=0x7fffdfb69ce0) at kernel/qapplication.cpp:3720
#21 0x00007f2b25f558eb in QApplication::notify (this=0x7fffdfb69a20, receiver=0x7fffdfb69a40, e=0x7fffdfb69ce0) at kernel/qapplication.cpp:3280
#22 0x00007f2b25b92c2b in QCoreApplication::notifyInternal (this=0x7fffdfb6a610, receiver=receiver@entry=0x1ea6bf0, event=event@entry=0x7fffdfb69ce0) at kernel/qcoreapplication.cpp:935
#23 0x00007f2b25f543da in sendSpontaneousEvent (event=0x7fffdfb69ce0, receiver=0x1ea6bf0) at ../../include/QtCore/../../src/corelib/kernel/qcoreapplication.h:231
#24 QApplicationPrivate::sendMouseEvent (receiver=0x1ea6bf0, event=0x7fffdfb69ce0, alienWidget=0x1ea6bf0, nativeWidget=0x1ed59e0, buttonDown=<optimized out>, lastMouseReceiver=..., spontaneous=true) at kernel/qapplication.cpp:2751
#25 0x00007f2b25fabcc0 in QWidgetWindow::handleMouseEvent (this=0x1ff0a40, event=0x7fffdfb6a0f0) at kernel/qwidgetwindow.cpp:543
#26 0x00007f2b25fade33 in QWidgetWindow::event (this=0x1ff0a40, event=0x7fffdfb6a0f0) at kernel/qwidgetwindow.cpp:210
#27 0x00007f2b25f4fb2c in QApplicationPrivate::notify_helper (this=0x1e19ec0, receiver=0x1ff0a40, e=0x7fffdfb6a0f0) at kernel/qapplication.cpp:3720
#28 0x00007f2b25f55000 in QApplication::notify (this=0x7fffdfb6a610, receiver=0x1ff0a40, e=0x7fffdfb6a0f0) at kernel/qapplication.cpp:3503
#29 0x00007f2b25b92c2b in QCoreApplication::notifyInternal (this=0x7fffdfb6a610, receiver=0x1ff0a40, event=0x7fffdfb6a0f0) at kernel/qcoreapplication.cpp:935
#30 0x00007f2b23471f82 in sendSpontaneousEvent (event=<optimized out>, receiver=<optimized out>) at ../../include/QtCore/../../src/corelib/kernel/qcoreapplication.h:231
#31 QGuiApplicationPrivate::processMouseEvent (e=0x4317870) at kernel/qguiapplication.cpp:1774
#32 0x00007f2b23473b45 in QGuiApplicationPrivate::processWindowSystemEvent (e=e@entry=0x4317870) at kernel/qguiapplication.cpp:1576
#33 0x00007f2b2345834f in QWindowSystemInterface::sendWindowSystemEvents (flags=...) at kernel/qwindowsysteminterface.cpp:572
#34 0x00007f2b155ae590 in userEventSourceDispatch (source=<optimized out>) at eventdispatchers/qeventdispatcher_glib.cpp:70
#35 0x00007f2b1f899c3d in g_main_context_dispatch () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#36 0x00007f2b1f899f20 in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#37 0x00007f2b1f899fcc in g_main_context_iteration () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#38 0x00007f2b25bebc57 in QEventDispatcherGlib::processEvents (this=0x1e4e9a0, flags=...) at kernel/qeventdispatcher_glib.cpp:418
#39 0x00007f2b25b903e2 in QEventLoop::exec (this=this@entry=0x7fffdfb6a4a0, flags=..., flags@entry=...) at kernel/qeventloop.cpp:204
#40 0x00007f2b261514b5 in QDialog::exec (this=0x1ed59e0) at dialogs/qdialog.cpp:541
#41 0x00007f2b27ba89cb in kdemain (_argc=<optimized out>, _argv=<optimized out>) at ../../kcmshell/main.cpp:307
#42 0x00007f2b277f6a40 in __libc_start_main (main=0x400730 <main(int, char**)>, argc=2, argv=0x7fffdfb6a758, init=<optimized out>, fini=<optimized out>, rtld_fini=<optimized out>, stack_end=0x7fffdfb6a748) at libc-start.c:289
#43 0x0000000000400769 in _start ()

Reported using DrKonqi