Does CentOS 5.4 properly handle leap seconds?

Apparently the IERS have announced a leap second due at midnight, June 30th this year.

Is CentOS/RHEL 5.4 properly updated to support/transition along with updated NTP systems? I was under the impression that it would need an updated tzdata package but wasn't sure.

UPDATE:

I checked the change-log for the tzdata package and noticed the following:

* Tue Feb 27 2007 Petr Machata <[email protected]> - 2007c-1
- Upstream 2007c
  - Pulaski County, Indiana, switched back to eastern time.
  - Turkey switches at 01:00 standard time, not at 01:00 UTC.
- Upstream 2007b
  - Changes to the commentary in "leapseconds".
- Resolves: #230089


* Tue Aug 22 2006 Petr Machata <[email protected]> - 2006j-1
- Upstream 2006j
  - Honduras stopped observing DST on Monday at 00:00
  - America/Bermuda will follow the US's lead next year
  - America/Moncton will use US-style rules next year
  - New Zone America/Blanc-Sablon, for Canadians who observe AST all
    year
  - New zone: America/Atikokan instead of America/Coral_Harbour
  - New zones: Europe/Jersey, Europe/Guernsey, Europe/Isle_of_Man
  - Historical changes
  - Commentary updates
- Upstream 2006i
  - localtime.c fixes
- Upstream 2006h
  - zic leapsecond fix

Is the "zic leapsecond fix" related?

Solution 1:

Your question is answered in the Red Hat knowledge base:

https://access.redhat.com/knowledge/articles/15145

Synopsis:
There is a known potential problem for some versions of RHEL 4 and 5 which may cause the kernel to crash at midnight for systems which are also running NTP. If you are patched higher than 5.4 and 4.8 you should be ok (assuming all appropriate related files are patched correctly). Alternatively you can choose to not run NTP however you will need to be sure you have the tzdata data file updated to the appropriate level.

Bottom line if you are on a fully updated system you should not have any issues.

Further information is available in Red Hat Bugzilla:
https://bugzilla.redhat.com/show_bug.cgi?id=479765

Solution 2:

You can verify that a given leap second update has been applied using the zdump command. On CentOS this is

/usr/sbin/zdump -v right/UTC

You're looking for a line similar to:

right/UTC  Sat Jun 30 23:59:60 2012 UTC = Sat Jun 30 23:59:60 2012 UTC isdst=0 gmtoff=0

This should be mentioned in the changelog for the tzdata package:

rpm -q --changelog tzdata | less

On a poorly-patched CentOS 5.7 box, I'm not finding this update. On current Ubuntu 11.10 and Debian squeeze boxes, I'm finding it. YMMV.

For more on this (from a Debian PoV but it should largely apply to CentOS): http://lists.debian.org/debian-user/2005/12/msg03343.html