Bug 455716

Summary:	Plasmashell segfaults when using touch on USB-C Monitor
Product:	[Plasma] plasmashell	Reporter:	LoNaAleim <unsecuredhl>
Component:	generic-crash	Assignee:	Plasma Bugs List <plasma-bugs-null>
Status:	RESOLVED UPSTREAM
Severity:	crash	CC:	nate
Priority:	NOR
Version First Reported In:	5.25.0
Target Milestone:	1.0
Platform:	Arch Linux
OS:	Linux
Latest Commit:		Version Fixed/Implemented In:
Sentry Crash Report:
Attachments:	Versions of KDE and plasma packages Outputs from plasmashell when the segfault happened

Description LoNaAleim 2022-06-21 13:14:50 UTC

Created attachment 150007 [details]
Versions of KDE and plasma packages

SUMMARY
I have a ThinkVision M14t: It is a USB-C monitor with touch and stylus input. https://www.lenovo.com/us/en/p/accessories-and-software/monitors/office/62a3uar1us

Since upgrading Plasma to 5.25.0, whenever I use touch to click anything on a plasmashell panel (application menu / task manager / quicklaunch) plasmashell just segfaults. I do not have that problem when I use the stylus to click things. 

Other applications (xournal / browser / onboard) react to stylus and touch without any issues.

I can provide core dumps from the crashes, but they are larger than the attachment file size limit.
I also ran plasmashell from a terminal with --replace and will attach the output.


STEPS TO REPRODUCE
1. Connect above mentioned monitor
2. Interact with plasmashell through touch (not stylus)
3. Plasmashell segfaults

OBSERVED RESULT
Plasmashell segfaults

EXPECTED RESULT
Plasmashell should not segfault


SOFTWARE/OS VERSIONS
OS: Arch linux 5.18.5-arch1-1
Qt Version: qt5-base 5.15.5+kde+r163-1

I couldn't really figure out which package versions exactly are needed w.r.t to KDE and Plasma, so I will attach a whole list as a file.

Comment 1 LoNaAleim 2022-06-21 13:15:34 UTC

Created attachment 150008 [details]
Outputs from plasmashell when the segfault happened

Comment 2 LoNaAleim 2022-06-21 13:19:23 UTC

I am working on getting a trace, the ticket was created immediately when I uploaded the first attachment.

Comment 3 LoNaAleim 2022-06-21 13:30:59 UTC

Here wo go, traces:

#1:

(gdb) bt
#0  0x00007fd6f2e8e36c in  () at /usr/lib/libc.so.6
#1  0x00007fd6f2e3e838 in raise () at /usr/lib/libc.so.6
#2  0x00007fd6f58eb384 in KCrash::defaultCrashHandler(int) () at /usr/lib/libKF5Crash.so.5
#3  0x00007fd6f2e3e8e0 in <signal handler called> () at /usr/lib/libc.so.6
#4  0x00007fd6eebf8ae1 in QXcbConnection::xi2ProcessTouch(void*, QXcbWindow*) () at /usr/lib/libQt5XcbQpa.so.5
#5  0x00007fd6eebc7667 in QXcbConnection::handleXcbEvent(xcb_generic_event_t*) () at /usr/lib/libQt5XcbQpa.so.5
#6  0x00007fd6eebcb8d0 in QXcbConnection::processXcbEvents(QFlags<QEventLoop::ProcessEventsFlag>) () at /usr/lib/libQt5XcbQpa.so.5
#7  0x00007fd6eebeecd8 in  () at /usr/lib/libQt5XcbQpa.so.5
#8  0x00007fd6f1f18c6b in g_main_context_dispatch () at /usr/lib/libglib-2.0.so.0
#9  0x00007fd6f1f6f001 in  () at /usr/lib/libglib-2.0.so.0
#10 0x00007fd6f1f16392 in g_main_context_iteration () at /usr/lib/libglib-2.0.so.0
#11 0x00007fd6f38d764c in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () at /usr/lib/libQt5Core.so.5
#12 0x00007fd6f38856ec in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () at /usr/lib/libQt5Core.so.5
#13 0x00007fd6f38901e9 in QCoreApplication::exec() () at /usr/lib/libQt5Core.so.5
#14 0x000055a4019d90e5 in  ()
#15 0x00007fd6f2e29290 in  () at /usr/lib/libc.so.6
#16 0x00007fd6f2e2934a in __libc_start_main () at /usr/lib/libc.so.6
#17 0x000055a4019d9495 in  ()

#2 #3 #4 #5 #6  (The same trace showed up multiple times)
#1  0x00007fd83538d667 in QXcbConnection::handleXcbEvent(xcb_generic_event_t*) () at /usr/lib/libQt5XcbQpa.so.5
#2  0x00007fd8353918d0 in QXcbConnection::processXcbEvents(QFlags<QEventLoop::ProcessEventsFlag>) () at /usr/lib/libQt5XcbQpa.so.5
#3  0x00007fd8353b4cd8 in  () at /usr/lib/libQt5XcbQpa.so.5
#4  0x00007fd838718c6b in g_main_context_dispatch () at /usr/lib/libglib-2.0.so.0
#5  0x00007fd83876f001 in  () at /usr/lib/libglib-2.0.so.0
#6  0x00007fd838716392 in g_main_context_iteration () at /usr/lib/libglib-2.0.so.0
#7  0x00007fd83a0d764c in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () at /usr/lib/libQt5Core.so.5
#8  0x00007fd83a0856ec in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () at /usr/lib/libQt5Core.so.5
#9  0x00007fd83a0901e9 in QCoreApplication::exec() () at /usr/lib/libQt5Core.so.5
#10 0x000055909d6880e5 in  ()
#11 0x00007fd839629290 in  () at /usr/lib/libc.so.6
#12 0x00007fd83962934a in __libc_start_main () at /usr/lib/libc.so.6
#13 0x000055909d688495 in  ()

Comment 4 Nate Graham 2022-06-21 18:24:42 UTC

#4  0x00007fd6eebf8ae1 in QXcbConnection::xi2ProcessTouch(void*, QXcbWindow*) () at /usr/lib/libQt5XcbQpa.so.5
#5  0x00007fd6eebc7667 in QXcbConnection::handleXcbEvent(xcb_generic_event_t*) () at /usr/lib/libQt5XcbQpa.so.5
#6  0x00007fd6eebcb8d0 in QXcbConnection::processXcbEvents(QFlags<QEventLoop::ProcessEventsFlag>) () at /usr/lib/libQt5XcbQpa.so.5

I don't see any KDE code here; I wonder if it might be an issue in Qt itself.

Comment 5 LoNaAleim 2022-06-23 19:45:03 UTC

Do you know a good way for me to test whether it is qt and not KDE?

I made some new observations today: 
I plugged in the screen and my plasma panels "froze" and became unresponsive before I even started using the display. 
Also: KRunner only started with significant delays. 

I wanted to get some logs so I tried `plasmashell --replace` but got this output:

kf.dbusaddons: Couldn't register name 'org.kde.plasmashell' with DBUS - another process owns it already!

Then I looked up the pid of plasmashell with ps, kill-9ed it and started it again. This time I got output (see below) but no panel showed up anywhere!

kf.plasma.quick: Applet preload policy set to 1
libGL error: MESA-LOADER: failed to open i965: /usr/lib/dri/i965_dri.so: cannot open shared object file: No such file or directory (search paths /usr/lib/dri, suffix _dri)
libGL error: failed to load driver: i965
libGL error: MESA-LOADER: failed to open i965: /usr/lib/dri/i965_dri.so: cannot open shared object file: No such file or directory (search paths /usr/lib/dri, suffix _dri)
libGL error: failed to load driver: i965
file:///usr/share/plasma/shells/org.kde.plasma.desktop/contents/views/Desktop.qml:70:5: QML Connections: Detected function "onConfigurationChanged" in Connections element. This is probably intended to be a signal handler but no signal of the target matches the name.
file:///usr/share/plasma/shells/org.kde.plasma.desktop/contents/views/Desktop.qml:70:5: QML Connections: Detected function "onRepaintNeeded" in Connections element. This is probably intended to be a signal handler but no signal of the target matches the name.
file:///usr/share/plasma/shells/org.kde.plasma.desktop/contents/views/Desktop.qml:67: TypeError: Cannot read property 'wallpaper' of null
file:///usr/share/plasma/shells/org.kde.plasma.desktop/contents/views/Desktop.qml:71: TypeError: Cannot read property 'wallpaper' of null
file:///usr/share/plasma/packages/org.kde.desktoptoolbox/contents/ui/ToolBoxContent.qml:217: TypeError: Cannot read property 'visible' of null
file:///usr/share/plasma/packages/org.kde.desktoptoolbox/contents/ui/ToolBoxContent.qml:216: TypeError: Cannot read property 'text' of null
file:///usr/share/plasma/shells/org.kde.plasma.desktop/contents/views/Desktop.qml:70:5: QML Connections: Detected function "onConfigurationChanged" in Connections element. This is probably intended to be a signal handler but no signal of the target matches the name.
file:///usr/share/plasma/shells/org.kde.plasma.desktop/contents/views/Desktop.qml:70:5: QML Connections: Detected function "onRepaintNeeded" in Connections element. This is probably intended to be a signal handler but no signal of the target matches the name.
file:///usr/share/plasma/shells/org.kde.plasma.desktop/contents/views/Desktop.qml:67: TypeError: Cannot read property 'wallpaper' of null
file:///usr/share/plasma/shells/org.kde.plasma.desktop/contents/views/Desktop.qml:71: TypeError: Cannot read property 'wallpaper' of null
qt.gui.icc: fromIccProfile: failed minimal tag size sanity
qt.gui.icc: fromIccProfile: failed minimal tag size sanity
qt.gui.icc: fromIccProfile: failed minimal tag size sanity
qt.gui.icc: fromIccProfile: failed minimal tag size sanity
file:///usr/share/plasma/packages/org.kde.desktoptoolbox/contents/ui/ToolBoxContent.qml:217: TypeError: Cannot read property 'visible' of null
file:///usr/share/plasma/packages/org.kde.desktoptoolbox/contents/ui/ToolBoxContent.qml:216: TypeError: Cannot read property 'text' of null
file:///usr/share/plasma/shells/org.kde.plasma.desktop/contents/views/Desktop.qml:70:5: QML Connections: Detected function "onConfigurationChanged" in Connections element. This is probably intended to be a signal handler but no signal of the target matches the name.
file:///usr/share/plasma/shells/org.kde.plasma.desktop/contents/views/Desktop.qml:70:5: QML Connections: Detected function "onRepaintNeeded" in Connections element. This is probably intended to be a signal handler but no signal of the target matches the name.
file:///usr/share/plasma/shells/org.kde.plasma.desktop/contents/views/Desktop.qml:67: TypeError: Cannot read property 'wallpaper' of null
file:///usr/share/plasma/shells/org.kde.plasma.desktop/contents/views/Desktop.qml:71: TypeError: Cannot read property 'wallpaper' of null
qt.gui.icc: fromIccProfile: failed minimal tag size sanity
file:///usr/share/plasma/packages/org.kde.desktoptoolbox/contents/ui/ToolBoxContent.qml:217: TypeError: Cannot read property 'visible' of null
file:///usr/share/plasma/packages/org.kde.desktoptoolbox/contents/ui/ToolBoxContent.qml:216: TypeError: Cannot read property 'text' of null
kio_http_cache_cleaner: Already running!
qt.gui.icc: fromIccProfile: failed minimal tag size sanity
qt.gui.icc: fromIccProfile: failed minimal tag size sanity
qt.gui.icc: fromIccProfile: failed minimal tag size sanity

Comment 6 LoNaAleim 2022-06-23 20:04:47 UTC

It indeed appears to be an issue with QT itself: https://bugreports.qt.io/browse/QTBUG-97603
As described by the Reporter, a workaround is uninstalling xf86-input-wacom.

Sorry to bother you, that didn't come up on my initial search.