Password works in virtual terminal but not in Gnome screensaver

Bug #435928 reported by Victor Engmark on 2009-09-24
This bug affects 1 person
Affects Status Importance Assigned to Milestone
GNOME Screensaver
gnome-screensaver (Ubuntu)
Ubuntu Desktop Bugs

Bug Description

Binary package hint: gnome-terminal

I've got an EEE PC running Ubuntu Netbook Remix 9.04:
$ uname -a
Linux hostname 2.6.28-15-generic #49-Ubuntu SMP tue Aug 18 18:40:08 UTC 2009 i686 GNU/Linux
$ lsb_release -rd
Description: Ubuntu 9.04
Release: 9.04
$ apt-cache policy gnome-screensaver
Installed: 2.24.0-0ubuntu6

After leaving it for a long time (probably 24+ hours) locked (using Ctrl-Alt-L), I'm unable to login with my regular password in Gnome. I've verified that I'm using the right input mode (US Dvorak) by clicking "Leave Message" and typing the password there. I've also changed the input mode to my second option, Norwegian, and typed the password (it's all a-zA-Z0-9 characters). I also verified that I'm able to log in in the first virtual terminal (Ctrl-Alt-F1) with the same password.

This problem has not occurred before.

I'll postpone rebooting in case you know anything else I could try to fix this.

affects: gnome-terminal (Ubuntu) → gnome-screensaver (Ubuntu)
Victor Engmark (victor-engmark) wrote :

This still happens once in a while, and seems to only happen if the computer is left for a while in screensaver mode (at least an hour seems to be the lower limit). Using the newest standard kernel:
$ uname -r

Victor Engmark (victor-engmark) wrote :

A workaround is to kill gnome-screensaver, but it's not restarted automatically, so screen locking (Ctrl+Alt+L) doesn't work anymore.

Is there some trick to see which password is actually sent to the underlying code? I suspect the problem can be with some sort of garbling because of the keyboard layout (USA Dvorak International), or somehow an empty password being sent.

Victor Engmark (victor-engmark) wrote :

Bug still present on Ubuntu NBR 9.10, with gnome-screensaver 2.28.0-0ubuntu3. Workaround discussed at <>.

Looked for possible duplicates, but it doesn't match the description of any of them:
gnome-screensaver-command -a
works fine, and the system does not become unresponsive.

Changed in gnome-screensaver (Ubuntu):
assignee: nobody → Ubuntu Desktop Bugs (desktop-bugs)
importance: Undecided → Low
status: New → Triaged
Martin (martin22) wrote :

For me this happened after a copy of files from one partition to another (with cp).

The solution was: chmod +s /sbin/unix_chkpwd

The cause was: the default options of cp don't keep setuid bits,

Victor Engmark (victor-engmark) wrote :

I checked for this solution around the web, and it looks like the ownership and permissions are already correct:

$ ls -la /sbin/unix_chkpwd
-rwxr-sr-x 1 root shadow 30400 2009-09-04 10:26 /sbin/unix_chkpwd

$ stat -c %a /sbin/unix_chkpwd

I should note that I'm using only a single login on this machine, and still this bug is not completely reproducible.

Changed in gnome-screensaver:
status: Unknown → New
Changed in gnome-screensaver:
importance: Unknown → Medium
Marc Deslauriers (mdeslaur) wrote :

Could you take a look at the "Authentication failure" sections on the following wiki page:

Also, are you still having this issue with Ubuntu 10.10 (Maverick)?

Changed in gnome-screensaver (Ubuntu):
status: Triaged → Incomplete
Changed in gnome-screensaver:
status: New → Expired
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