Bug 2253115

I booted the Fedora Rawhide/40 KDE Plasma live image Fedora-KDE-Live-x86_64-Rawhide-20231204.n.0.iso in GNOME Boxes QEMU/KVM VMs with 3D acceleration disabled using the llvmpipe mesa 23.3.0 driver in a Fedora 39 KDE Plasma host. To work around the VM getting stuck on the Plasma 5.90.0 on Wayland splash screen as I reported at https://bugs.kde.org/show_bug.cgi?id=477643 I changed to VT2 using the keyboard menu in the top bar of GNOME Boxes and selecting Ctrl+Alt+F2. When I changed back to VT1, Plasma was shown with the Plasma Welcome program open. I started Konsole. I installed obs-studio 30.0.0. I started obs in Konsole. I clicked cancel on the wizard. I added a Screen Capture (Pipewire) source with QEMU screen. I closed obs. A crash notification was shown. drkonqi appeared which was unexpected since I didn't think obs-studio was a KDE program. obs crashed in QtWaylandClient::QWaylandWindow::decoration when closing 3 different times. Since this=0x0 for QtWaylandClient::QWaylandWindow::decoration, the crash might've been a null pointer dereference.

Application: obs (obs), signal: Segmentation fault

[KCrash Handler]
#4  0x00007fe143da72f6 in QtWaylandClient::QWaylandWindow::decoration (this=0x0) at /usr/src/debug/qt6-qtwayland-6.6.1-1.fc40.x86_64/src/client/qwaylandwindow.cpp:1104
#5  0x00007fe143da22cd in QtWaylandClient::QWaylandShmBackingStore::resize (this=this@entry=0x5588370f2a80, size=...) at /usr/src/debug/qt6-qtwayland-6.6.1-1.fc40.x86_64/src/client/qwaylandshmbackingstore.cpp:297
#6  0x00007fe143da23ed in QtWaylandClient::QWaylandShmBackingStore::ensureSize (this=this@entry=0x5588370f2a80) at /usr/src/debug/qt6-qtwayland-6.6.1-1.fc40.x86_64/src/client/qwaylandshmbackingstore.cpp:194
#7  0x00007fe143da26d1 in QtWaylandClient::QWaylandShmBackingStore::beginPaint (this=0x5588370f2a80, region=...) at /usr/src/debug/qt6-qtwayland-6.6.1-1.fc40.x86_64/src/client/qwaylandshmbackingstore.cpp:172
#8  0x00007fe15c0846b1 in QBackingStore::beginPaint(QRegion const&) () from /lib64/libQt6Gui.so.6
#9  0x00007fe15cc2a596 in QWidgetRepaintManager::paintAndFlush() () from /lib64/libQt6Widgets.so.6
#10 0x00007fe15cc1e758 in QWidget::event(QEvent*) () from /lib64/libQt6Widgets.so.6
#11 0x00007fe15cbc3168 in QApplicationPrivate::notify_helper(QObject*, QEvent*) () from /lib64/libQt6Widgets.so.6
#12 0x00007fe15b7a0e08 in QCoreApplication::notifyInternal2 (receiver=0x55883492d4c0, event=0x558836fc4970) at /usr/src/debug/qt6-qtbase-6.6.1-1.fc40.x86_64/src/corelib/kernel/qcoreapplication.cpp:1121
#13 0x00007fe15b7a100d in QCoreApplication::sendEvent (receiver=<optimized out>, event=<optimized out>) at /usr/src/debug/qt6-qtbase-6.6.1-1.fc40.x86_64/src/corelib/kernel/qcoreapplication.cpp:1539
#14 0x00007fe15b7a4d05 in QCoreApplicationPrivate::sendPostedEvents (receiver=0x0, event_type=0, data=0x558832c8dca0) at /usr/src/debug/qt6-qtbase-6.6.1-1.fc40.x86_64/src/corelib/kernel/qcoreapplication.cpp:1901
#15 0x00007fe15b7a507d in QCoreApplication::sendPostedEvents (receiver=<optimized out>, event_type=<optimized out>) at /usr/src/debug/qt6-qtbase-6.6.1-1.fc40.x86_64/src/corelib/kernel/qcoreapplication.cpp:1760
#16 0x00007fe15ba6daef in postEventSourceDispatch (s=0x558832d49220) at /usr/src/debug/qt6-qtbase-6.6.1-1.fc40.x86_64/src/corelib/kernel/qeventdispatcher_glib.cpp:243
#17 0x00007fe15a320e5c in g_main_context_dispatch_unlocked.lto_priv () from /lib64/libglib-2.0.so.0
#18 0x00007fe15a37bdd8 in g_main_context_iterate_unlocked.isra () from /lib64/libglib-2.0.so.0
#19 0x00007fe15a31ead3 in g_main_context_iteration () from /lib64/libglib-2.0.so.0
#20 0x00007fe15ba6d39f in QEventDispatcherGlib::processEvents (this=0x558832c8c820, flags=...) at /usr/src/debug/qt6-qtbase-6.6.1-1.fc40.x86_64/src/corelib/kernel/qeventdispatcher_glib.cpp:393
#21 0x00007fe15b7adbcb in QEventLoop::exec (this=this@entry=0x7fff9d0d3bd0, flags=..., flags@entry=...) at /usr/src/debug/qt6-qtbase-6.6.1-1.fc40.x86_64/src/corelib/global/qflags.h:34
#22 0x00007fe15b7a99cd in QCoreApplication::exec () at /usr/src/debug/qt6-qtbase-6.6.1-1.fc40.x86_64/src/corelib/global/qflags.h:74
#23 0x00005588324f0073 in main ()
[Inferior 1 (process 3339) detached]


Reproducible: Always


Steps to Reproduce:
1. Boot a Fedora 39 KDE Plasma installation updated to 2023-12-6 with updates-testing enabled
2. Log in to Plasma 5.27.9 on Wayland
3. Start Konsole
4. Install GNOME Boxes if it isn't already with sudo dnf install gnome-boxes
5. Download Fedora-KDE-Live-x86_64-Rawhide-20231204.n.0.iso from https://koji.fedoraproject.org/koji/buildinfo?buildID=2327615
6. Start GNOME Boxes
7. Boot Fedora-KDE-Live-x86_64-Rawhide-20231204.n.0.iso in a GNOME Boxes QEMU/KVM VM with 3 GiB RAM, UEFI enabled, and 3D acceleration disabled 
8. To work around https://bugs.kde.org/show_bug.cgi?id=477643, switch to VT2 in GNOME boxes via the keyboard menu Ctrl+Alt+F2 and back to VT1 with Ctrl+Alt+F1 when the Plasma 5.90.0 splash screen is shown
9. Start Konsole in the VM 
10. In Konsole, Install obs-studio with sudo dnf install obs-studio
11. Start obs in Konsole
12. Click Cancel in the wizard in obs
13. Click + to add a source in the Sources box
14. Select Screen capture (Pipewire)
15. Click OK
16. Select QEMU screen and OK
17. Close obs

Actual Results:  
obs crashed when closing

Expected Results:  
obs shouldn't have crashed

Linux/KDE Plasma: Fedora Rawhide/40
(available in About System)
KDE Plasma Version: 5.90.0
KDE Frameworks Version: 5.246.0
Qt Version: 6.6.1

The problem didn't seem to happen when I booted the same image on bare metal. The problem might have something to do with running in a VM.