Bug 366575

Summary:	kscreen_backend_launcher segfault when debugging is enabled
Product:	[Plasma] KScreen	Reporter:	Georg <georgmueller>
Component:	libkscreen	Assignee:	Sebastian Kügler <sebas>
Status:	RESOLVED FIXED
Severity:	normal
Priority:	NOR
Version First Reported In:	5.7.3
Target Milestone:	---
Platform:	Fedora RPMs
OS:	Linux
Latest Commit:		Version Fixed/Implemented In:
Sentry Crash Report:

Description Georg 2016-08-10 07:50:08 UTC

I tried to debug a kscreen issue and when enabling debugging via ~/.config/QtProject/qtlogging.ini, kscreen_backend_launcher crashed due to a null pointer dereference.

Reproducible: Always

Steps to Reproduce:
1. set the following content in ~/.config/QtProject/qtlogging.ini
[rules]
*.debug=false
kscreen.xrandr.debug=true
2. run a kscreen command to enable a secondary screen
In my case, this was: kscreen-doctor output.320.enable
3. segmentation fault

Actual Results:  
The problem lies in the following line:
https://github.com/KDE/libkscreen/blob/v5.7.3/backends/xrandr/xrandrconfig.cpp#L521

kscreenOutput->currentMode() is null, thus kscreenOutput->currentMode()->size() causes the segmentation fault.

Comment 1 Sebastian Kügler 2016-08-10 11:04:21 UTC

Proposed fix: https://phabricator.kde.org/D2330

Comment 2 Sebastian Kügler 2016-08-10 11:56:17 UTC

Patch is in master now. I'll see if I can backport it to 5.7.4, but it should get a few days of testing, first.

Thanks for the report!