linux-kernel - Re: [PATCH v4] net: sock: move ->sk

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Message-ID: <1463591842.18194.135.camel@edumazet-glaptop3.roam.corp.google.com>
Date:	Wed, 18 May 2016 10:17:22 -0700
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Andrey Ryabinin <aryabinin@...tuozzo.com>
Cc:	"David S. Miller" <davem@...emloft.net>,
	Hannes Frederic Sowa <hannes@...essinduktion.org>,
	Rainer Weikusat <rweikusat@...ileactivedefense.com>,
	Eric Dumazet <edumazet@...gle.com>, netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4] net: sock: move ->sk_shutdown out of bitfields.

On Wed, 2016-05-18 at 19:19 +0300, Andrey Ryabinin wrote:
> ->sk_shutdown bits share one bitfield with some other bits in sock struct,
> such as ->sk_no_check_[r,t]x, ->sk_userlocks ...
> sock_setsockopt() may write to these bits, while holding the socket lock.
> 
> In case of AF_UNIX sockets, we change ->sk_shutdown bits while holding only
> unix_state_lock(). So concurrent setsockopt() and shutdown() may lead
> to corrupting these bits.
> 
> Fix this by moving ->sk_shutdown bits out of bitfield into a separate byte.
> This will not change the 'struct sock' size since ->sk_shutdown moved into
> previously unused 16-bit hole.
> 
> Signed-off-by: Andrey Ryabinin <aryabinin@...tuozzo.com>
> Suggested-by: Hannes Frederic Sowa <hannes@...essinduktion.org>
> ---

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