Re: kauditd hold queue overflow in 4.11

[Laurent Bigonville <bigon@debian.org>]

Le 11/07/17 à 00:23, Paul Moore a écrit :
> On Mon, Jul 10, 2017 at 4:01 PM, Laurent Bigonville <bigon@debian.org> wrote:
>> Le 10/07/17 à 18:00, Paul Moore a écrit :
>>
>>> On Mon, Jul 10, 2017 at 10:59 AM, Laurent Bigonville <bigon@debian.org>
>>> wrote:
>>>> Hi,
>>>>
>>>> With 4.11.6 (that has been uploaded in debian unstable) I get a lot of
>>>> messages in dmesg like
>>>>
>>>> [100052.120468] audit: audit_lost=66041 audit_rate_limit=0
>>>> audit_backlog_limit=8192
>>>> [100052.120470] audit: kauditd hold queue overflow
>>>>
>>>> And it also seems that the messages are not stored in auditd logs
>>>> anymore.
>>>>
>>>> https://git.kernel.org/linus/264d509637d95f9404e52ced5003ad352e0f6a26
>>>> seems
>>>> to be included in this release
>>>>
>>>> An idea?
>>> 7
>>> I'm going to assume that your backlog limit is set to a sane value for
>>> your system's configuration, so that leaves me with two commits that
>>> may be of interest:
>>>
>>> * 1df30f8264b8 ("audit: fix the RCU locking for the auditd_connection
>>> structure")
>>>
>>> This was a manual backport of a v4.12 patch to v4.11, looking now, I
>>> see it should be in +v4.11.5 so that probably isn't your problem ...
>>>
>>> * c81be52a3ac0 ("audit: fix a race condition with the auditd tracking
>>> code")
>>>
>>> This patch is relatively new and was just sent up to Linus during the
>>> next merge window; it's a race condition fix so reproducing it can be
>>> tricky, although it may be easily reproducible on your system at the
>>> moment (luck you!).  If you aren't in a position to apply the patch,
>>> the workaround is rather simple: restart auditd.
>>>
>>> If none of the above works, let me know, but I strongly suspect you're
>>> tripping over the race condition fixed in that last patch.
>>>
>> I didn't test the patch yet, but I restarted the auditd daemon 2 times and
>> after that the queue has been flushed and I got all the message since this
>> noon in the audit logs.
> That sounds right; I'm guessing the patch above should be a more permanent fix.
>

The patch should be applied in 4.13-rc7 right?

It seems to fix the main issue (all the audit messages being logged in 
dmesg) but I can still see from time to time the following message:

[   14.747565] audit: audit_lost=59 audit_rate_limit=0 audit_backlog_limit=64
[   14.747566] audit: kauditd hold queue overflow


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