Occasional login failure and artefacts

[schollsky]

Login fails in spite of correct password - I've waited to report this to rule out possible typos. The error occured over 50 times now and happens more often when no network connection is available. Despite of that it is hard to reproduce. Sometimes it occurs when network connection is up. A sure sign of a situation when the password will not be accepted is graphical artifacts at the login screen. These vanish after failed attempt and normal login is possible at second attempt - no failure occured then.

O.K., here's how to reproduce it: I changed my login manager to gdm and back to lightdm
by using "dpkg-reconfigure lightdm" as root. The first time lightdm is in use after that the artifacts show up and login is only possible at second attempt.

System in use here is XUbuntu 11.10, lightdm is 1.0.6-0ubuntu1.2.

Bug is possibly related to Bug #882955.

[Marc Deslauriers (mdeslaur)]

Thanks for taking the time to report this bug and helping to make Ubuntu better. We appreciate the difficulties you are facing, but this appears to be a "regular" (non-security) bug. I have unmarked it as a security issue since this bug does not show evidence of allowing attackers to cross privilege boundaries nor directly cause loss of data/privacy. Please feel free to report any other bugs you may find.

[schollsky (schollsky)]

The bug seems is gone now - but I don't know the reason. It's probably due to recent lightdm or Xorg update.

[Robert Ancell (robert-ancell)]

OK, closing assumed fixed. Please reopen if it occurs again. /var/log/lightdm/lightdm.log should tell you more if it reoccurs.

[Stephane Peters (stephane-peters)]

Hello,

This behavior (need to enter password 2 or 3 times) happened nearly from the beginning.

It is a fresh install of a standard xubuntu 16.04 LTS with my old homedir copied from the previous 16.04 machine (that has crashed).

Packages are just installed when needed, so that forgotten packages are not borrowed from the old machine.

Btw
lightdm: 1.18.3-0ubuntu1.1

Today I had to enter my password 3 times.
here are some extracts of 3 log files where I have found 2 errors in a short time :
/var/log/syslog
/var/log/lightdm/lightdm.log
/var/log/lightdm/seat0-greeter.log

Maybe useful information:
When unlocked, I select the session with <Ctrl><Alt>7,
but once locked, I have to select Ctrl><Alt>8;
Or <Ctrl><Alt>7 displays a black screen with something in french like this:
   This session is locked
   you will be redirected to the unlock dialog automatically in a few seconds

# Syslog: A connection to the bus can't be made
tail -30 /var/log/syslog

Jun 11 14:07:14 dlt0001ptrstp lightdm[1248]: ** (lightdm:1248): WARNING **: Error using VT_WAITACTIVE 7 on /dev/tty0: Interrupted system call
Jun 11 14:07:14 dlt0001ptrstp org.gtk.vfs.Daemon[23411]: A connection to the bus can't be made
Jun 11 14:07:15 dlt0001ptrstp systemd[1]: Started Session c32 of user lightdm.
Jun 11 14:07:16 dlt0001ptrstp org.a11y.Bus[7986]: ** (process:7997): WARNING **: Failed to register client: GDBus.Error:org.freedesktop.DBus.Error.ServiceUnknown: The name org.gnome.SessionManager was not provided by any .service files
Jun 11 14:07:16 dlt0001ptrstp org.a11y.Bus[7986]: Activating service name='org.a11y.atspi.Registry'
Jun 11 14:07:16 dlt0001ptrstp org.a11y.Bus[7986]: Successfully activated service 'org.a11y.atspi.Registry'
Jun 11 14:07:16 dlt0001ptrstp org.a11y.atspi.Registry[8002]: SpiRegistry daemon is running with well-known name - org.a11y.atspi.Registry
Jun 11 14:07:20 dlt0001ptrstp lightdm[1248]: ** (lightdm:1248): WARNING **: Error using VT_WAITACTIVE 7 on /dev/tty0: Interrupted system call
Jun 11 14:07:20 dlt0001ptrstp org.gtk.vfs.Daemon[7986]: A connection to the bus can't be made
Jun 11 14:07:21 dlt0001ptrstp systemd[1]: Started Session c33 of user lightdm.
Jun 11 14:07:21 dlt0001ptrstp org.a11y.Bus[8079]: ** (process:8090): WARNING **: Failed to register client: GDBus.Error:org.freedesktop.DBus.Error.ServiceUnknown: The name org.gnome.SessionManager was not provided by any .service files
Jun 11 14:07:21 dlt0001ptrstp org.a11y.Bus[8079]: Activating service name='org.a11y.atspi.Registry'
Jun 11 14:07:22 dlt0001ptrstp org.a11y.Bus[8079]: Successfully activated service 'org.a11y.atspi.Registry'
Jun 11 14:07:22 dlt0001ptrstp org.a11y.atspi.Registry[8095]: SpiRegistry daemon is running with well-known name - org.a11y.atspi.Registry
Jun 11 14:07:27 dlt0001ptrstp org.gtk.vfs.Daemon[8079]: A connection to the bus can't be made

# /var/log/lightdm/lightdm.log : Error using VT_WAITACTIVE
[+1635057.87s] DEBUG: Continue authentication
[+1635057.90s] DEBUG: Session pid=23480: Authentication complete with return value 0: Success
[+1635057.90s] DEBUG: Authenticate result for user <user>: Success
[+1635057.90s] DEBUG: User <user> authorized
[+1635057.90s] DEBUG: Greeter s...

[Stephane Peters (stephane-peters)]

Hello,

same problem today, and same message appears in syslog:

Jun 13 13:44:13 dlt0001ptrstp lightdm[1201]: ** (lightdm:1201): WARNING **: Error using VT_WAITACTIVE 7 on /dev/tty0: Interrupted system call
Jun 13 13:44:13 dlt0001ptrstp org.gtk.vfs.Daemon[14134]: A connection to the bus can't be made
Jun 13 13:44:13 dlt0001ptrstp org.a11y.atspi.Registry[14143]: XIO: fatal IO error 11 (Resource temporarily unavailable) on X server ":1"
Jun 13 13:44:13 dlt0001ptrstp org.a11y.atspi.Registry[14143]: after 37 requests (37 known processed) with 0 events remaining.
Jun 13 13:44:14 dlt0001ptrstp systemd[1]: Started Session c7 of user lightdm.
Jun 13 13:44:14 dlt0001ptrstp org.a11y.atspi.Registry[14660]: SpiRegistry daemon is running with well-known name - org.a11y.atspi.Registry
Jun 13 13:44:31 dlt0001ptrstp org.gtk.vfs.Daemon[14651]: A connection to the bus can't be made

I had to enter the password twice.

Regards,
--
Stephane Peters.