[Bug 1609003] Re: tty users logouts not correctly recorded

Mon Sep 19 11:35:06 UTC 2016

** Description changed:

  1) Release: Ubuntu Gnome 14.04.4 and Xubuntu 14.04.4
  2) Version of package: util-linux 2.20.1-5.1ubuntu20.7
  3) I would expect that: when a user makes a new login, the number of "users" shown in uptime and w is incremented, and when the user makes a logout that number is decremented.
  4) Instead, this does not happen when the login is made through a local tty.

  If a user logs in through a ttyx (by pressing from the GUI Ctrl+Alt+Fx), and then logs out, the number of users shown in the outputs of w and uptime still considers him.
  This number of users (shown in w and uptime) is in fact always incremented when a new ttyx with a successful login is used; but it is never decremented when that user logs out (unless there is a reboot, obviously).

  After a login from just the GUI, the system is:

  $ uptime
  17:16:09 up  7:05,  1 users,  load average: 0,43, 0,50, 0,38

  $ who
  user   :0           2016-08-02 10:21 (:0)

  Then I press Ctrl+Alt+F1 and I log in into /dev/tty1. While I'm logged
  in, it is correctly shown that

  $ uptime
  17:21:09 up  7:05,  2 users,  load average: 0,40, 0,20, 0,31

  $ who
- lgking   :0           2016-08-02 10:21 (:0)
- lgking   tty1         2016-08-02 10:25
+ user   :0           2016-08-02 10:21 (:0)
+ user   tty1         2016-08-02 10:25

  Then I log out from tty1. The situation is the following:

  $ uptime
  17:26:09 up  7:05,  2 users,  load average: 0,35, 0,21, 0,32

  $ who
  user   :0           2016-08-02 10:21 (:0)

  So the output of who is correct, but uptime still indicates 2 users logged in the system. The same happens with w, which indicates 2 users connected, but then lists just one of them (the only one actually connected!).
  The numbers and the times are just an example.
  Maybe the getty is not working properly with utmp?
  This systematically happened in two different machines, with Ubuntu Gnome 14.04.4 and Xubuntu 14.04.4.
  I didn't check the box, but this may be a security vulnerability, because it shows in a wrong way the number of connected users.

  ProblemType: Bug
  DistroRelease: Ubuntu 14.04
  Package: util-linux 2.20.1-5.1ubuntu20.7
  ProcVersionSignature: Ubuntu 3.13.0-92.139-generic 3.13.11-ckt39
  Uname: Linux 3.13.0-92-generic x86_64
  ApportVersion: 2.14.1-0ubuntu3.21
  Architecture: amd64
  CurrentDesktop: GNOME
  Date: Tue Aug  2 17:24:49 2016
  InstallationDate: Installed on 2014-05-31 (794 days ago)
  InstallationMedia: Ubuntu-GNOME 14.04 LTS "Trusty Tahr" - Release amd64 (20140416.2)
  ProcEnviron:
   TERM=xterm
   PATH=(custom, no user)
   XDG_RUNTIME_DIR=<set>
   LANG=it_IT.UTF-8
   SHELL=/bin/bash
  SourcePackage: util-linux
  UpgradeStatus: No upgrade log present (probably fresh install)

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https://bugs.launchpad.net/bugs/1609003

Title:
  tty users logouts not correctly recorded

Status in util-linux package in Ubuntu:
  Confirmed

Bug description:
  1) Release: Ubuntu Gnome 14.04.4 and Xubuntu 14.04.4
  2) Version of package: util-linux 2.20.1-5.1ubuntu20.7
  3) I would expect that: when a user makes a new login, the number of "users" shown in uptime and w is incremented, and when the user makes a logout that number is decremented.
  4) Instead, this does not happen when the login is made through a local tty.

  If a user logs in through a ttyx (by pressing from the GUI Ctrl+Alt+Fx), and then logs out, the number of users shown in the outputs of w and uptime still considers him.
  This number of users (shown in w and uptime) is in fact always incremented when a new ttyx with a successful login is used; but it is never decremented when that user logs out (unless there is a reboot, obviously).

  After a login from just the GUI, the system is:

  $ uptime
  17:16:09 up  7:05,  1 users,  load average: 0,43, 0,50, 0,38

  $ who
  user   :0           2016-08-02 10:21 (:0)

  Then I press Ctrl+Alt+F1 and I log in into /dev/tty1. While I'm logged
  in, it is correctly shown that

  $ uptime
  17:21:09 up  7:05,  2 users,  load average: 0,40, 0,20, 0,31

  $ who
  user   :0           2016-08-02 10:21 (:0)
  user   tty1         2016-08-02 10:25

  Then I log out from tty1. The situation is the following:

  $ uptime
  17:26:09 up  7:05,  2 users,  load average: 0,35, 0,21, 0,32

  $ who
  user   :0           2016-08-02 10:21 (:0)

  So the output of who is correct, but uptime still indicates 2 users logged in the system. The same happens with w, which indicates 2 users connected, but then lists just one of them (the only one actually connected!).
  The numbers and the times are just an example.
  Maybe the getty is not working properly with utmp?
  This systematically happened in two different machines, with Ubuntu Gnome 14.04.4 and Xubuntu 14.04.4.
  I didn't check the box, but this may be a security vulnerability, because it shows in a wrong way the number of connected users.

  ProblemType: Bug
  DistroRelease: Ubuntu 14.04
  Package: util-linux 2.20.1-5.1ubuntu20.7
  ProcVersionSignature: Ubuntu 3.13.0-92.139-generic 3.13.11-ckt39
  Uname: Linux 3.13.0-92-generic x86_64
  ApportVersion: 2.14.1-0ubuntu3.21
  Architecture: amd64
  CurrentDesktop: GNOME
  Date: Tue Aug  2 17:24:49 2016
  InstallationDate: Installed on 2014-05-31 (794 days ago)
  InstallationMedia: Ubuntu-GNOME 14.04 LTS "Trusty Tahr" - Release amd64 (20140416.2)
  ProcEnviron:
   TERM=xterm
   PATH=(custom, no user)
   XDG_RUNTIME_DIR=<set>
   LANG=it_IT.UTF-8
   SHELL=/bin/bash
  SourcePackage: util-linux
  UpgradeStatus: No upgrade log present (probably fresh install)

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