xfsettingsd crashed with SIGSEGV

[Thomas A. F. Thorne]

Crashed whil trying to setup VNC from Windows into Ubuntu.

ProblemType: Crash
DistroRelease: Ubuntu 18.04
Package: xfce4-settings 4.12.4-0ubuntu0.18.04.1
ProcVersionSignature: Ubuntu 4.15.0-45.48-generic 4.15.18
Uname: Linux 4.15.0-45-generic x86_64
NonfreeKernelModules: lkp_Ubuntu_4_15_0_45_48_generic_51
ApportVersion: 2.20.9-0ubuntu7.5
Architecture: amd64
CrashCounter: 1
CurrentDesktop: ubuntu:GNOME
Date: Thu Jul 18 16:27:11 2019
ExecutablePath: /usr/bin/xfsettingsd
InstallationDate: Installed on 2017-11-16 (609 days ago)
InstallationMedia: Ubuntu 16.04.3 LTS "Xenial Xerus" - Release amd64 (20170801)
ProcCmdline: xfsettingsd
SegvAnalysis:
 Segfault happened at: 0x7f0f6a3a9337: mov 0x18(%rdx),%rax
 PC (0x7f0f6a3a9337) ok
 source "0x18(%rdx)" (0x00000018) not located in a known VMA region (needed readable region)!
 destination "%rax" ok
SegvReason: reading NULL VMA
Signal: 11
SourcePackage: xfce4-settings
StacktraceTop:
 () at /usr/lib/x86_64-linux-gnu/libxklavier.so.16
 ()
 g_type_create_instance () at /usr/lib/x86_64-linux-gnu/libgobject-2.0.so.0
 () at /usr/lib/x86_64-linux-gnu/libgobject-2.0.so.0
 g_object_new_with_properties () at /usr/lib/x86_64-linux-gnu/libgobject-2.0.so.0
Title: xfsettingsd crashed with SIGSEGV
UpgradeStatus: Upgraded to bionic on 2018-07-27 (356 days ago)
UserGroups: adm cdrom dialout dip docker lpadmin plugdev sambashare sudo wireshark

[Apport retracing service (apport)]

StacktraceTop:
 xkl_config_rec_get_full_from_server (rules_file_out=rules_file_out@entry=0x0, data=0x7f0f540056c0, engine=0x0) at xklavier_props.c:182
 xkl_config_rec_get_from_server (data=<optimized out>, engine=<optimized out>) at xklavier_props.c:273
 xfce_keyboard_layout_helper_init (helper=0x558400e2d850) at keyboard-layout.c:121
 g_type_create_instance () from /tmp/apport_sandbox_0a5dkvl4/usr/lib/x86_64-linux-gnu/libgobject-2.0.so.0
 ?? () from /tmp/apport_sandbox_0a5dkvl4/usr/lib/x86_64-linux-gnu/libgobject-2.0.so.0

[Dmitry Katsubo (dma-k)]

In my case xfsettingsd results segfault during the session startup:

[Tue Oct 8 11:14:22 2019] xfsettingsd[2538]: segfault at 18 ip 00007fc318301f2d sp 00007ffdcfc9f2d0 error 4 in libxklavier.so.16.4.0[7fc3182f7000+d000]
[Tue Oct 8 11:14:22 2019] Code: 48 89 45 28 48 c1 e2 03 4a 8d 7c e0 08 e8 eb 51 ff ff e9 1e fe ff ff e8 11 5a ff ff 90 41 54 48 89 d1 49 89 fc 55 48 89 f5 53 <48> 8b 42 18 48 89 d3 48 89 fa 48 89 ef 48 8b b0 28 01 00 00 e8 0a
[Tue Oct 8 11:14:22 2019] traps: light-locker[2510] trap int3 ip:7f017b666c75 sp:7fff462b5400 error:0 in libglib-2.0.so.0.5800.3[7f017b62e000+7e000]

When I start xfsettingsd afterwards from xterm, it starts and functions correctly. I have difficulty capturing the backtrace with gdb unless somebody can give a hint how to do it. I have added

export XFSETTINGSD_DEBUG=1
ulimit -c unlimited
/etc/X11/Xsession

to ./.vnc/xstartup but it does not generate a core dump :(

Additional info:

* Debian Buster, uname: 4.19.0-6-amd64 #1 SMP Debian 4.19.67-2+deb10u1 (2019-09-20) x86_64 GNU/Linux
* xfce4-settings:amd64 v4.12.4-1
* libxklavier16:amd64 v5.4-4
* Xfce is running under tightvncserver.

[Theo Linkspfeifer (lastonestanding)]

Ubuntu bug report:
https://bugs.launchpad.net/ubuntu/+source/xfce4-settings/+bug/1837071

You could try using systemd-coredump to obtain a backtrace.

https://www.freedesktop.org/software/systemd/man/systemd-coredump.html

[Dmitry Katsubo (dma-k)]

Backtrace:

Stack trace of thread 2513:
#0 0x00007ff6195b4f2d n/a (libxklavier.so.16)
#1 0x000055f59a9c9b15 n/a (xfsettingsd)
#2 0x00007ff618dec107 g_type_create_instance (libgobject-2.0.so.0)
#3 0x00007ff618dce548 n/a (libgobject-2.0.so.0)
#4 0x00007ff618dcfcc5 g_object_new_with_properties (libgobject-2.0.so.0)
#5 0x00007ff618dd0731 g_object_new (libgobject-2.0.so.0)
#6 0x000055f59a9c584c n/a (xfsettingsd)
#7 0x00007ff618ad909b __libc_start_main (libc.so.6)
#8 0x000055f59a9c5ada n/a (xfsettingsd)

It matches one provided in above mentioned bug (I've compared with https://launchpadlibrarian.net/433653979/Stacktrace.txt).

[Gitbot (gitbot)]

Sean Davis referenced this bugreport in commit b73852916f1b9f47466dd2d1c22c433ae3ee4528

Handle failure to get Xkl engine for display (bug #16017)

https://git.xfce.org/xfce/xfce4-settings/commit?id=b73852916f1b9f47466dd2d1c22c433ae3ee4528

[Gitbot (gitbot)]

Sean Davis referenced this bugreport in commit 9fc73425ab3bea380872bac813ce45890b4070d6

Handle failure to get Xkl engine for display (bug #16017)

https://git.xfce.org/xfce/xfce4-settings/commit?id=9fc73425ab3bea380872bac813ce45890b4070d6

[Bluesabre-1 (bluesabre-1)]

The above commits (xfce-4.14 and master) should resolve this error. This issue came down to xkl_engine_get_instance occasionally returning NULL, but the rest of the code assumed it was always successful. If possible, please test this and let us know if you see any other issues.

[Launchpad Janitor (janitor)]

This bug was fixed in the package xfce4-settings - 4.14.3-0ubuntu1

---------------
xfce4-settings (4.14.3-0ubuntu1) focal; urgency=medium

  * New upstream bugfix release.
    - Fixes xfsettingsd crash with VNC (LP: #1837071)

 -- Sean Davis <email address hidden> Sun, 12 Apr 2020 12:15:12 -0400

[AlexXXX (avd-84)]

i have same bug in 4.14.3-0ubuntu1
i make screenshot but can't paste it here