netdev - Re: [PATCH net] packet: fix race condition in packet_set

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Date:   Fri, 02 Dec 2016 12:17:16 -0500 (EST)
From:   David Miller <davem@...emloft.net>
To:     eric.dumazet@...il.com
Cc:     netdev@...r.kernel.org, philip.pettersson@...il.com
Subject: Re: [PATCH net] packet: fix race condition in packet_set_ring

From: Eric Dumazet <eric.dumazet@...il.com>
Date: Wed, 30 Nov 2016 14:55:36 -0800

> From: Philip Pettersson <philip.pettersson@...il.com>
> 
> When packet_set_ring creates a ring buffer it will initialize a
> struct timer_list if the packet version is TPACKET_V3. This value
> can then be raced by a different thread calling setsockopt to
> set the version to TPACKET_V1 before packet_set_ring has finished.
> 
> This leads to a use-after-free on a function pointer in the
> struct timer_list when the socket is closed as the previously
> initialized timer will not be deleted.
> 
> The bug is fixed by taking lock_sock(sk) in packet_setsockopt when
> changing the packet version while also taking the lock at the start
> of packet_set_ring.
> 
> Fixes: f6fb8f100b80 ("af-packet: TPACKET_V3 flexible buffer implementation.")
> Signed-off-by: Philip Pettersson <philip.pettersson@...il.com>
> Signed-off-by: Eric Dumazet <edumazet@...gle.com>

Applied and queued up for -stable, thanks.