lightdm-gtk-greeter crashed with SIGSEGV in cairo_surface_get_type()

Bug #1422794 reported by jasonmerc
32
This bug affects 4 people
Affects Status Importance Assigned to Milestone
lightdm-gtk-greeter (Ubuntu)
Medium
Unassigned

Bug Description

I'm on Xubuntu 15.04 Daily Build. I simply changed the desktop environment in the Login screen from Xubuntu to Xfce, logged in, and was told that a system problem was detected before the panels/icons of the desktop environment even loaded.

ProblemType: Crash
DistroRelease: Ubuntu 15.04
Package: lightdm-gtk-greeter 2.0.0-0ubuntu1
ProcVersionSignature: Ubuntu 3.18.0-13.14-generic 3.18.5
Uname: Linux 3.18.0-13-generic x86_64
ApportVersion: 2.16.1-0ubuntu2
Architecture: amd64
Date: Tue Feb 17 11:01:23 2015
ExecutablePath: /usr/sbin/lightdm-gtk-greeter
InstallationDate: Installed on 2015-02-10 (7 days ago)
InstallationMedia: Xubuntu 15.04 "Vivid Vervet" - Alpha amd64 (20150208)
ProcCmdline: /usr/sbin/lightdm-gtk-greeter
ProcEnviron:
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=en_US.UTF-8
 SHELL=/bin/false
SegvAnalysis:
 Segfault happened at: 0x7f010b7f7870 <cairo_surface_get_type>: mov 0x10(%rdi),%eax
 PC (0x7f010b7f7870) ok
 source "0x10(%rdi)" (0x00000010) not located in a known VMA region (needed readable region)!
 destination "%eax" ok
SegvReason: reading NULL VMA
Signal: 11
SourcePackage: lightdm-gtk-greeter
StacktraceTop:
 cairo_surface_get_type () from /usr/lib/x86_64-linux-gnu/libcairo.so.2
 greeter_background_save_xroot ()
 _start ()
Title: lightdm-gtk-greeter crashed with SIGSEGV in cairo_surface_get_type()
UpgradeStatus: No upgrade log present (probably fresh install)
UserGroups:

Revision history for this message
jasonmerc (jason-s-m) wrote :
Revision history for this message
Apport retracing service (apport) wrote :

StacktraceTop:
 cairo_surface_get_type (surface=surface@entry=0x0) at ../../../../src/cairo-surface.c:221
 set_surface_as_root (surface=0x0, screen=0x7f010d63a0d0) at greeterbackground.c:1610
 greeter_background_save_xroot (background=<optimized out>) at greeterbackground.c:1019
 start_session () at lightdm-gtk-greeter.c:2024
 _g_closure_invoke_va (closure=0x0, closure@entry=0x7f010d68c550, return_value=0x7f010d5e8fb0, return_value@entry=0x0, instance=0x7f010d75c920, instance@entry=0x7f010d670850, args=0x33, args@entry=0x7fff46ec77e0, n_params=0, param_types=0x0) at /build/buildd/glib2.0-2.43.3/./gobject/gclosure.c:831

Revision history for this message
Apport retracing service (apport) wrote : Stacktrace.txt
Revision history for this message
Apport retracing service (apport) wrote : StacktraceSource.txt
Revision history for this message
Apport retracing service (apport) wrote : ThreadStacktrace.txt
Changed in lightdm-gtk-greeter (Ubuntu):
importance: Undecided → Medium
tags: removed: need-amd64-retrace
tags: added: xenial
Revision history for this message
Launchpad Janitor (janitor) wrote :

Status changed to 'Confirmed' because the bug affects multiple users.

Changed in lightdm-gtk-greeter (Ubuntu):
status: New → Confirmed
information type: Private → Public
Revision history for this message
Stefan Dösinger (stefandoesinger-b) wrote :

I believe this has to do with the hostname changing during lightdm start and login. The connection to the X server fails somehow.

I posted some details on https://bugs.launchpad.net/ubuntu/+source/lightdm-gtk-greeter/+bug/1677058 before I found this bug here.

Revision history for this message
Sean Davis (bluesabre) wrote :

Is this still a problem with a supported Xubuntu release?

Changed in lightdm-gtk-greeter (Ubuntu):
status: Confirmed → Incomplete
Revision history for this message
T Mee (tm221) wrote :

For me, this problem occurs in Ubuntu-18.04 and 20.04. It occurs when dynamic hostnames are used. However, different errors seem to cause the LightDM sessions to fail. But you can look at the logs to see how many "new session c" sessions are logged. After a reboot and one login, there should only be two (using a single display). The problem occurs because lightdm starts before the hostname is changed from localhost to the one from DNS. So all we have to do is start lightdm after that by simply changing /lib/systemd/system/lightdm.service to add "network-online.target" to the end of this line:

After=systemd-user-sessions.service <email address hidden> plymouth-quit.service

It works if the network is not plugged in too--the hostname remains localhost.

This is my solution. Maybe an expert can review it to see if it is the right change and hopefully backport it to Ubuntu-18.04 too.

Revision history for this message
Launchpad Janitor (janitor) wrote :

[Expired for lightdm-gtk-greeter (Ubuntu) because there has been no activity for 60 days.]

Changed in lightdm-gtk-greeter (Ubuntu):
status: Incomplete → Expired
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