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From: Eric Dumazet <eric.dumazet@gmail.com>
To: David Miller <davem@davemloft.net>
Cc: synapse@hippy.csoma.elte.hu, netdev@vger.kernel.org
Subject: Re: PROBLEM: BUG (NULL ptr dereference in ipv4_dst_check)
Date: Fri, 29 Jul 2011 17:43:28 +0200	[thread overview]
Message-ID: <1311954208.2843.31.camel@edumazet-HP-Compaq-6005-Pro-SFF-PC> (raw)
In-Reply-To: <20110729.081902.300678107767426313.davem@davemloft.net>

Le vendredi 29 juillet 2011 à 08:19 -0700, David Miller a écrit :
> From: Eric Dumazet <eric.dumazet@gmail.com>
> Date: Fri, 29 Jul 2011 17:11:46 +0200
> 
> > Thats tricky, because I am not sure we dont need RCU protection since we
> > can now exchange dst neighbour on the fly.
> > 
> > Following patch would only reduce the window of bug, not a complete
> > fix...
> > 
> > David, any opinion on this ?
> 
> Indeed, old code worked because we invalidated entire route cache
> entry, and we never before ran arp_bind_neighbour() except on new
> route cache entires before they become globally visible.
> 
> I think when we change an existing neigh we will need to release old
> neigh via RCU, at a minimum.


Oh well, we already use RCU in neigh_destroy(), so adding rcu would need
to change all dst_get_neighbour() callers to be in one rcu_read_lock()
section.

I'll take a look, I suspect its mostly already done.




  reply	other threads:[~2011-07-29 15:43 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-07-29 13:18 PROBLEM: BUG (NULL ptr dereference in ipv4_dst_check) synapse
2011-07-29 13:33 ` Eric Dumazet
2011-07-29 14:26   ` synapse
2011-07-29 14:36     ` Eric Dumazet
2011-07-29 14:39       ` David Miller
2011-07-29 14:41         ` Eric Dumazet
2011-07-29 14:44           ` synapse
2011-07-29 15:11             ` Eric Dumazet
2011-07-29 15:19               ` David Miller
2011-07-29 15:43                 ` Eric Dumazet [this message]
2011-07-30  5:00                   ` Eric Dumazet
2011-08-01  8:57                     ` synapse
2011-08-01  9:15                       ` Eric Dumazet
2011-08-01 15:25                         ` synapse
2011-08-03 10:34                     ` David Miller
2011-08-08 13:08                       ` synapse
2011-08-09  6:56                       ` [PATCH] net: fix potential neighbour race in dst_ifdown() Eric Dumazet
2011-08-10  4:47                         ` David Miller

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