XDMCP Request packet with no addresses crashes LightDM

Caused bu the change in bug 1481561

lightdm looked ready to release in vivid, but I encountered this bug when looking through the comments. I marked bug 1481561 'verification-failed' in response to your comment. Please mark the bug 'verification-done-vivid' if lightdm in vivid-proposed should still be released with any appropriate commentary.
Thanks,

Was a CVE assigned to this? Do you want me to request one?

It wasn't - you're welcome to do one.

Affected stable versions: 1.14.3, 1.16.0, 1.16.1, 1.16.2, 1.16.3, 1.16.4, 1.16.5.

The way I found this was by testing the SRU in vivid - for some reason the X server was sending Request packets with a addresses field empty. Other Ubuntu releases are not doing this. I haven't yet investigated if why it was doing this.

Hello Robert, or anyone else affected,

Accepted lightdm into wily-proposed. The package will build now and be available at https://launchpad.net/ubuntu/+source/lightdm/1.16.6-0ubuntu1 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!

Hello Robert, or anyone else affected,

Accepted lightdm into vivid-proposed. The package will build now and be available at https://launchpad.net/ubuntu/+source/lightdm/1.14.4-0ubuntu1 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!

This bug was fixed in the package lightdm - 1.16.6-0ubuntu1

---------------
lightdm (1.16.6-0ubuntu1) wily; urgency=medium

  * New upstream release:
    - Handle XDMCP Request packet with no addresses. (LP: #1516831)
    - Don't start LightDM if the XDMCP server is configured with a key that
      doesn't exist. (LP: #1517685)
    - Add IP addresses to XDMCP log messages.
    - Refactor XDMCP error handling.
    - Add more tests.

 -- Robert Ancell <email address hidden> Fri, 20 Nov 2015 15:46:15 +1300

The verification of the Stable Release Update for lightdm 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 regressions.

This bug was fixed in the package lightdm - 1.14.4-0ubuntu1

---------------
lightdm (1.14.4-0ubuntu1) vivid; urgency=medium

  * New upstream release:
    - Handle XDMCP Request packet with no addresses. (LP: #1516831)
    - Don't start LightDM if the XDMCP server is configured with a key that
      doesn't exist. (LP: #1517685)
    - Add IP addresses to XDMCP log messages.
    - Refactor XDMCP error handling.
    - Add more tests.

 -- Robert Ancell <email address hidden> Fri, 20 Nov 2015 16:01:15 +1300