[Bug 1966800] Re: systemd locks up due to incorrect handling of time zone changes

[Łukasz Zemczak]

Hello Matt, or anyone else affected,

Accepted systemd into focal-proposed. The package will build now and be
available at
https://launchpad.net/ubuntu/+source/systemd/245.4-4ubuntu3.18 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 on 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, what testing has been
performed on the package and change the tag from verification-needed-
focal to verification-done-focal. If it does not fix the bug for you,
please add a comment stating that, and change the tag to verification-
failed-focal. In either case, without details of your testing we will
not be able to proceed.

Further information regarding the verification process can be found at
https://wiki.ubuntu.com/QATeam/PerformingSRUVerification .  Thank you in
advance for helping!

N.B. The updated package will be released to -updates after the bug(s)
fixed by this package have been verified and the package has been in
-proposed for a minimum of 7 days.

** Changed in: systemd (Ubuntu Focal)
       Status: New => Fix Committed

** Tags added: verification-needed verification-needed-focal

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https://bugs.launchpad.net/bugs/1966800

Title:
  systemd locks up due to incorrect handling of time zone changes

Status in systemd package in Ubuntu:
  Fix Released
Status in systemd source package in Focal:
  Fix Committed
Status in systemd package in Fedora:
  Unknown

Bug description:
  [Impact]

  This bug can cause systemd timers to lock up systems using the
  Europe/Dublin timezone if certain OnCalendar values are used. If the
  timer is enabled at boot, this bug prevents the system from booting.
  If the timer is started later, systemd becomes unresponsive.

  [Test Plan]

  * Create a systemd service and corresponding timer scheduled for 01:00
  on Sundays:

  $ cat /etc/systemd/system/lp-1966800-reproducer.timer
   [Unit]
   Description=LP 1966800 reproducer

   [Timer]
   OnCalendar=Sun *-*-* 01:00:00
   Persistent=true

   [Install]
   WantedBy=timers.target

   $ cat /etc/systemd/system/lp-1966800-reproducer.service
   [Service]
   ExecStart=/usr/bin/echo "LP 1966800 reproducer"

   $ systemctl daemon-reload

  * Set the date to 21 March, 2021 in the Europe/Dublin timezone (need
  to disable NTP first):

   $ timedatectl set-ntp false
   $ timedatectl set-time "2021-03-21"
   $ timedatectl set-timezone Europe/Dublin

  * Try to start the timer, and observe that systemd becomes
  unresponsive. This command will time out, as will `systemctl status`
  etc.

   $ systemctl start lp-1966800-reproducer.timer

  [Where problems could occur]

  The patch makes changes in the calendar spec code, which is used by
  systemd timers to determine the next time to trigger a timer. If this
  patch breaks something, it would be related to the triggering of
  systemd timers.

  [Original Description]

  Recently on systems in Ireland, systemd became unresponsive due the
  change from GMT to Irish Standard Time. This is due to Ireland being
  unique in having their standard time during the summer, unlike most
  regions.

  Related to: https://bugzilla.redhat.com/show_bug.cgi?id=1941335
  Fixed by: https://github.com/systemd/systemd-stable/commit/a8b66ca9af811148b67ee952ab32748f88b8bba3

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