netdev - Re: nf_conntrack_h323: Fix locking in process

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Date:	Fri, 15 Jan 2016 23:57:12 +0100
From:	Sebastian Pöhn <sebastian.poehn@...il.com>
To:	Florian Westphal <fw@...len.de>
Cc:	netfilter-devel@...r.kernel.org, netdev@...r.kernel.org
Subject: Re: nf_conntrack_h323: Fix locking in process_urq

You are right. The problem is fixed since 3.15 with the expect_lock refactoring.
We found this in 3.12. Probably this is something for stable releases 3.14 and earlier.

Am 15.01.2016 11:42 nachm. schrieb "Florian Westphal" <fw@...len.de>:
>
> Sebastian Pöhn <sebastian.poehn@...il.com> wrote:
>
> [ CC netfilter-devel ]
>
> > nf_ct_remove_expectations has to be called under nf_conntrack_expect_lock
>
> But nf_ct_remove_expectations grabs that lock?
>
> Added in:
>
> commit ca7433df3a672efc88e08222cfa4b3aa965ca324
> Author: Jesper Dangaard Brouer <brouer@...hat.com>
> netfilter: conntrack: seperate expect locking from nf_conntrack_lock
>
> > diff --git a/net/netfilter/nf_conntrack_h323_main.c b/net/netfilter/nf_conntrack_h323_main.c
> > index 9511af0..d477375 100644
> > --- a/net/netfilter/nf_conntrack_h323_main.c
> > +++ b/net/netfilter/nf_conntrack_h323_main.c
> > @@ -1518,7 +1518,9 @@ static int process_urq(struct sk_buff *skb, struct nf_conn *ct,
> >         }
> >  
> >         /* Clear old expect */
> > +       spin_lock_bh(&nf_conntrack_expect_lock);
> >         nf_ct_remove_expectations(ct);
>
> ... so I'd expect deadlock.
>