Bug 2375596

Summary: Fedora 42 Kinoite SDDM segfaults after connecting an external monitor
Product: [Fedora] Fedora Reporter: thrashwerk
Component: sddmAssignee: Neal Gompa <ngompa13>
Status: CLOSED DUPLICATE QA Contact: Fedora Extras Quality Assurance <extras-qa>
Severity: medium Docs Contact:
Priority: unspecified    
Version: 42CC: jgrulich, kde-sig, m, ngompa13, pg_forums, pierluigi.fiorini, rdieter, suraj.ghimire7
Target Milestone: ---Keywords: Desktop
Target Release: ---   
Hardware: x86_64   
OS: Linux   
Whiteboard:
Fixed In Version: Doc Type: ---
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Clone Of: Environment:
Last Closed: 2025-06-30 16:54:23 UTC Type: ---
Regression: --- Mount Type: ---
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
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Description Flags
full syslog
none
photo of screen after the crash none

Description thrashwerk 2025-06-30 15:24:29 UTC 
I turn on my ThinkPad T14 laptop, enter the LUKS passphrase, see the SDDM login screen, connect an external monitor via USB-C cable to the laptop and the login screen disappears showing the previous LUKS passphrase screen which is non-functional, basically a wallpaper.

This happens on Fedora Kinoite 42.20250629.0 and 42.20250630.0.
The problem didn't exist on 42.20250624.0.

Don't know if it's related but kscreenlocker also started segfaulting at the same time (Bug 2375593) except it doesn't matter if a monitor is connected.

Reproducible: Always

Steps to Reproduce:
1. Boot computer
2. At SDDM login screen connect an external monitor
Actual Results:
The login screen disappears and basically what is a picture of the previous LUKS passphrase screen is displayed.

Expected Results:
The login screen continues to work and is mirrored to the new monitor.

Additional Information:
Segfault from the logs (I'll also attach a full log):
Jun 30 14:21:35 db-tp kernel: sddm-greeter-qt[1557]: segfault at 1b ip 00007fab6d6dd19d sp 00007ffdd23de730 error 4 in d8a22d47e187298e95f6673634de3a4d863dce8205e994c89020d8e82c05bb.file[319d,7fab6d6da000+7000] likely on CPU 5 (core 1, socket 0)
Jun 30 14:21:35 db-tp kernel: Code: be 02 00 00 00 4c 89 e7 31 c0 e8 2e da ff ff 49 83 7e 10 00 0f 85 8b 00 00 00 49 8b 87 b0 01 00 00 48 85 c0 74 32 4c 8b 63 18 <4c> 8b 70 18 44 8b 6d a8 4c 89 e7 e8 53 d9 ff ff 48 83 ec 08 31 d2
Comment 1 thrashwerk 2025-06-30 15:24:59 UTC 
Created attachment 2095788 [details]
full syslog
Comment 2 thrashwerk 2025-06-30 15:26:10 UTC 
Created attachment 2095789 [details]
photo of screen after the crash
Comment 3 pg_tips 2025-06-30 16:17:56 UTC 
Suspect this may be due to the issue in qt6-qtwayland 6.9.1-2 described in https://bugzilla.redhat.com/show_bug.cgi?id=2375356

The stack trace involving libLayerShellQtInterface.so.6 here looks similar to what was seen in #2375356.
Comment 4 Jan Grulich 2025-06-30 16:54:23 UTC 

*** This bug has been marked as a duplicate of bug 2375356 ***