From mboxrd@z Thu Jan  1 00:00:00 1970
From: Patrick McHardy <kaber@trash.net>
Subject: Re: [PATCH 0/2] rework of userspace expectation support
Date: Wed, 13 Apr 2011 13:55:45 +0200
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References: <20110412215458.3145.40830.stgit@decadence> <4DA58AE2.7000204@trash.net> <4DA58D48.4010307@netfilter.org>
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Cc: netfilter-devel@vger.kernel.org
To: Pablo Neira Ayuso <pablo@netfilter.org>
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Am 13.04.2011 13:47, schrieb Pablo Neira Ayuso:
> On 13/04/11 13:37, Patrick McHardy wrote:
>> Am 12.04.2011 23:59, schrieb Pablo Neira Ayuso:
>>> Hi Patrick,
>>>
>>> The following patches rework the userspace expectation support
>>> to fix one problematic scenario: if the master conntrack vanishes
>>> while there are still userspace expectations, we hit an oops
>>> in the destroy event path for expectations.
>>
>> Just wondering, how can this happen? We take a reference for
>> userspace expectations just as we do for kernel expectations.
>>
>> Ok, I see, we are releasing it again at the end of
>> ctnetlink_create_expect(), that seems to be the actual problem
>> if I'm not mistaken.
> 
> Indeed, we have keep that reference, that would fix the problem.

We definitely need to hold it anyways since destroy_conntrack()
releases it again.

> Still, with the curent approach the userspace expectation will be valid
> after the master conntrack has expired.
> 
> So we can do the following: Fix this refcount issue in -stable and
> current, and schedule these patches for nf-next to change the behaviour.
> 
> What do you think?

I don't know, what's the difference to non-userspace expectations?
The same applies to them, we don't require the master to still be
active for expectations.