gdm crashes when it encounters a .desktop session file it can't read

Thank you for your bug report and sending it to GNOME

why did you change the status there?

Brian Cameron (one of the GDM guys) says this issue is not happening for him with stock upstream gdm!

Ubuntu's GDM is currently at version 2.30.0, but upstream's latest stable release is 2.30.2 [1]. It fixes a fair assortment of issues, so upgrading to it could magically cure this bug (among others).
[1] http://ftp.acc.umu.se/pub/gnome/sources/gdm/2.30/

If not, the problem has to be one of the myriads of patches we have downstream! The crash will be worked around by the latest sugar-session in Lucid, but you can replicate it by creating a new session file at /usr/share/xsessions/problem.desktop, with these contents:

[Desktop Entry]
Encoding=UTF-8
Name=Problem
GenericName=Problem
Exec=xterm
Type=Application

There is some really awesome analysis in the upstream bug report[2], so if you want to work on this bug, I recommend starting there :)
[2] https://bugzilla.gnome.org/show_bug.cgi?id=615462

sorry the comment crossed there, 2.30.2 has been in lucid-proposed for some weeks but add new crashers and doesn't solve some of the bugs it was supposed to fix, see bug #579044 for example

The issue seems to be due to the failsafe change from https://bugzilla.gnome.org/show_bug.cgi?id=607703, Didier you wrote the change could you look at the issue? It should not exit when no comment can be read but deal with it nicely rather

"+ res = get_session_comment_for_file (filename, &comment);
+ if (! res) {
+ g_critical ("Cannot read specified session file: %s", filename);
+ g_free (filename);
+ exit (1);
+ }
"

it seems that should return and not exit in such cases

Hi Sebastien!

Sorry about changing the bug status. That was just a silly accident when I was wondering why the upstream bug watcher still said New :)
(I tinker mercilessly with anything that uses Javascript)

I installed gdm from lucid-proposed, which gives me 2.30.2.is.2.30.0-0ubuntu1

Restarted my computer to be sure but the crash still occurred, as before, with the session file I described.

right, the bug is likely the one I indicated before, Didier will try to get it fixed in the next upload, the version in lucid-proposed got downgraded due to issue in 2.30.2, we want to try to get a set of easy fixes in lucid-updates before trying to get a new version now

This bug was fixed in the package gdm - 2.30.2-0ubuntu3

---------------
gdm (2.30.2-0ubuntu3) maverick; urgency=low

  * debian/patches/30_don_t_save_failsafe_session.patch: (LP: #542345)
    - return FALSE instead of exiting on .desktop file without a comment
 -- Didier Roche <email address hidden> Thu, 10 Jun 2010 10:32:58 +0200

pushed in maverick, waiting for pushing in -proposed from that commit: http://bazaar.launchpad.net/~ubuntu-desktop/gdm/ubuntu/revision/257

sru team, the debdiff for the stable update which has been uploaded is on bug #403441

Accepted gdm into lucid-proposed, the package will build now and be available in a few hours. Please test and give feedback here. See https://wiki.ubuntu.com/Testing/EnableProposed for documentation how to enable and use -proposed. Thank you in advance!

I've managed to reproduce the crash creating the .desktop file on the /usr/share/xsessions dir, I've updated the gdm package to the proposed one, tested it again and there's no crash this time, the session works fine. Marking this as verification done, thanks all.

This bug was fixed in the package gdm - 2.30.2.is.2.30.0-0ubuntu2

---------------
gdm (2.30.2.is.2.30.0-0ubuntu2) lucid-proposed; urgency=low

  * debian/patches/94_git_null_free_crash.patch:
    - git change to fix a crasher (lp: #403441)
  * debian/patches/95_git_name_escaping.patch:
    - git change to fix escaping issues leading to crashes (lp: #499690),
      or to having incorrect usernames displayed (lp: #585128)

  [ Didier Roche ]
  * debian/patches/30_don_t_save_failsafe_session.patch: (LP: #542345)
    - return FALSE instead of exiting on .desktop file without a comment
 -- Sebastien Bacher <email address hidden> Thu, 17 Jun 2010 15:41:17 +0200