[Bug 1086775] Re: bind9 uses high CPU after lucid->precise upgrade

[Alex Bligh]

OK so my working hypothesis is this. On Lucid /var/cache/bind is created
simply by virtue of it being a directory within the package (see the
bind9.list file). The group write permission is added by the postinst.
If the Lucid package was installed, then removed, then installed again,
the following happens:

1. the first install would create /var/cache/bind with whatever
ownership is in the package, and also /etc/bind/rndc.key with root
ownership. The postinst thens runs and fixes the group write permission
on /var/cache/bind.

2. the removal would delete /var/cache/bind as it is not a conffile, but
not /etc/bind/rndc.key

3. the second install would create /var/cache/bind again with (possibly)
the wrong permissions, and the postinst script would not fix it.

This probably doesn't go wrong in Lucid because nothing writes to the
cache directory and/or bind survives without the cache. It's certainly
empty  here on our Lucid boxes pre upgrade to Precise. But the Precise
upgrade requires to write there, and then dies.

The above would happen (AFAICT) if *ANY* version ever released of the
Lucid bind9.deb had broken permissions, as subsequent upgrades would not
fix it.

The problem with only fixing permissions if some rather random file in
/etc/ is owned by root is it is inherently fragile. Is there any reason
why the bind cache directory should ever not be writeable by the group
that owns it?

-- 
You received this bug notification because you are a member of Ubuntu
Server Team, which is subscribed to bind9 in Ubuntu.
https://bugs.launchpad.net/bugs/1086775

Title:
  bind9 uses high CPU after lucid->precise upgrade

To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/bind9/+bug/1086775/+subscriptions