netdev - Re: [PATCH net-next] fix NULL pointer dereference in br_handle

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Date:	Thu, 12 Sep 2013 09:08:58 -0700
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	vyasevic@...hat.com
Cc:	Hong zhi guo <honkiko@...il.com>, netdev@...r.kernel.org,
	David Miller <davem@...emloft.net>, zhiguohong@...cent.com
Subject: Re: [PATCH net-next] fix NULL pointer dereference in br_handle_frame

On Thu, 2013-09-12 at 11:50 -0400, Vlad Yasevich wrote:
> On 09/12/2013 11:24 AM, Eric Dumazet wrote:
> > On Thu, 2013-09-12 at 10:42 -0400, Vlad Yasevich wrote:
> >
> >> Don't all tests for IFF_BRIDGE_PORT on the bridge receive path become
> >> redundant as well?
> >
> > Sure but anyway this part is net-next material
> >
> > Lets fix the bug first.
> 
> Seems like the race is possible in net as well.  If we just include the
> original patch, then br_add_if() also has to be modified to make sure
> the flag is set properly before netdev_rx_handler_register() is called.
> 
> If we remove the need to check the flag during bridge input handling,
> then br_add_if() change is not necessary.

Yep, really testing IFF_BRIDGE_PORT in fast path is currently racy.

rcu protection should be enough.



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