netdev - Re: [patch net] macvlan: fix passthru mode race between dev removal and rx path

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Message-ID: <1368131733.13473.103.camel@edumazet-glaptop>
Date:	Thu, 09 May 2013 13:35:33 -0700
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Jiri Pirko <jiri@...nulli.us>
Cc:	netdev@...r.kernel.org, davem@...emloft.net, sri@...ibm.com,
	kaber@...sh.net, linux-kernel@...r.kernel.org, mtesar@...hat.com
Subject: Re: [patch net] macvlan: fix passthru mode race between dev removal
 and rx path

On Thu, 2013-05-09 at 16:23 +0200, Jiri Pirko wrote:
> Currently, if macvlan in passthru mode is created and data are rxed and
> you remove this device, following panic happens:
> 
> NULL pointer dereference at 0000000000000198
> IP: [<ffffffffa0196058>] macvlan_handle_frame+0x153/0x1f7 [macvlan]
> 
...
> 
> Reason of the panic is that list_first_entry() is blindly called in
> macvlan_handle_frame() even if the list was empty. vlan is set to
> incorrect pointer which leads to the crash.
> 
> I'm fixing this by protecting port->vlans list by rcu and by preventing
> from getting incorrect pointer in case the list is empty.
> 
> Introduced by: commit eb06acdc85585f2 "macvlan: Introduce 'passthru' mode to takeover the underlying device"
> 
> Signed-off-by: Jiri Pirko <jiri@...nulli.us>
> ---

Acked-by: Eric Dumazet <edumazet@...gle.com>


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