unity-greeter crashed with SIGSEGV in gdk_window_get_type_hint()

[Ursula Junque]

[Impact]
Unity Greeter can crash when X clients create X windows. This results in Ubuntu going to failsafe mode.

When an X window appears Unity Greeter receives a Map event. Unity Greeter attempts to get a GdkWindow object for the window in the event. If the window was destroyed before it does this it gets a NULL pointer. Unity Greeter did not check for this case.

[Test Case]
This is a bug that only occurs if windows rapidly appear and disappear. Can be verified on machines that are exhibiting the problem (perhaps linked to indicators failing to start). Check errors.ubuntu.com shows problem does not occur when fix applied.
[Errors Bucket]
https://errors.ubuntu.com/bucket/?id=/usr/sbin/unity-greeter%3A11%3Agdk_window_get_type_hint%3Aunity_greeter_focus_upon_map%3A_unity_greeter_focus_upon_map_gdk_filter_func%3Agdk_event_apply_filters%3Agdk_event_source_translate_event

[Regression Potential]
Low, the change just checks for the NULL pointer and ignores the map event.

[Apport retracing service (apport)]

StacktraceTop:
 gdk_window_get_type_hint (window=0x0) at /build/buildd/gtk+3.0-3.5.16/./gdk/gdkwindow.c:10210
 unity_greeter_focus_upon_map (event=<optimized out>, gxevent=<optimized out>) at unity-greeter.c:715
 _unity_greeter_focus_upon_map_gdk_filter_func (xevent=<optimized out>, event=<optimized out>, self=<optimized out>) at unity-greeter.c:757
 gdk_event_apply_filters (xevent=xevent@entry=0x7fff5d0f6e60, event=event@entry=0xb1d9d0, window=window@entry=0x827000) at /build/buildd/gtk+3.0-3.5.16/./gdk/x11/gdkeventsource.c:81
 gdk_event_source_translate_event (xevent=0x7fff5d0f6e60, event_source=0x8301a0) at /build/buildd/gtk+3.0-3.5.16/./gdk/x11/gdkeventsource.c:202

[Launchpad Janitor (janitor)]

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

[Didier Roche-Tolomelli (didrocks)]

Robert, can you have a look at this bug please?

[Sebastien Bacher (seb128)]

is that still an issue?

[Richard Hansen (rhansen)]

this may or may not be related to bug #1086132

[Launchpad Janitor (janitor)]

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

[Ursula Junque (ursinha)]

I just hit this bug again, now on raring.

[Launchpad Janitor (janitor)]

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

[tad1073 (tad1073)]

I'm getting this on 13.10

[Vincent Thiele (vincentthiele)]

Even a fresh install has this Problem. Mostly after you start your pc and login. (Ubuntu 13.04)

[Vincent Thiele (vincentthiele)]

Crash report:

[Maura (mdhausman)]

Having this issue from a freshly installed, fully updated and upgraded 13.10.

[Launchpad Janitor (janitor)]

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

[Launchpad Janitor (janitor)]

This bug was fixed in the package unity-greeter - 14.04.2-0ubuntu1

---------------
unity-greeter (14.04.2-0ubuntu1) trusty; urgency=medium

  * New upstream release:
    - Handle a window being destroyed after we get the map event and try and
      focus it (LP: #1048131)
    - Add accessible description to back button (LP: #1266366)
    - Fix attempted removal of dead source
    - Apply the same unity color corrections to the average color in shutdown
      dialog
 -- Robert Ancell <email address hidden> Wed, 05 Feb 2014 10:01:12 +0000

[Chris Halse Rogers (raof)]

The regression risk for checking for NULL might be low, but the package uploaded to the precise-proposed queue is instead a new upstream version - 0.2.10 - which contains unrelated changes and for some reason switches the packaging from 3.0 (quilt) to 1.0.

Please upload again, without the unnecessary packaging changes (and more documentation of the new upstream release if you choose to upload it).

[Brian Murray (brian-murray)]

Hello Ursula, or anyone else affected,

Accepted unity-greeter into precise-proposed. The package will build now and be available at http://launchpad.net/ubuntu/+source/unity-greeter/0.2.9-0ubuntu1.3 in a few hours, and then in the -proposed repository.

Please help us by testing this new package. See https://wiki.ubuntu.com/Testing/EnableProposed for documentation how to enable and use -proposed. Your feedback will aid us getting this update out to other Ubuntu users.

If this package fixes the bug for you, please add a comment to this bug, mentioning the version of the package you tested, and change the tag from verification-needed to verification-done. If it does not fix the bug for you, please add a comment stating that, and change the tag to verification-failed. In either case, details of your testing will help us make a better decision.

Further information regarding the verification process can be found at https://wiki.ubuntu.com/QATeam/PerformingSRUVerification . Thank you in advance!

[Robert Ancell (robert-ancell)]

I'm going to go ahead and say this is fixed in -proposed since there's been no complaints about it being there.

[Colin Watson (cjwatson)]

The verification of the Stable Release Update for unity-greeter has completed successfully and the package has now been released to -updates. Subsequently, the Ubuntu Stable Release Updates Team is being unsubscribed and will not receive messages about this bug report. In the event that you encounter a regression using the package from -updates please report a new bug using ubuntu-bug and tag the bug report regression-update so we can easily find any regresssions.

[Launchpad Janitor (janitor)]

This bug was fixed in the package unity-greeter - 0.2.9-0ubuntu1.3

---------------
unity-greeter (0.2.9-0ubuntu1.3) precise; urgency=medium

  * debian/patches/dont-focus-destroyed-window.patch:
    - Handle a window being destroyed after we get the map event and try and
      focus it (LP: #1048131)
 -- Robert Ancell <email address hidden> Wed, 09 Apr 2014 13:58:13 +1200

[Rolf Leggewie (r0lf)]

quantal has seen the end of its life and is no longer receiving any updates. Marking the quantal task for this ticket as "Won't Fix".

[Rolf Leggewie (r0lf)]

saucy has seen the end of its life and is no longer receiving any updates. Marking the saucy task for this ticket as "Won't Fix".