netdev - Re: [PATCH v2] socket: don't return uninitialized addresses on concurrent socket shutdown

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Date:	Fri, 15 Nov 2013 22:32:49 -0800
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Hannes Frederic Sowa <hannes@...essinduktion.org>
Cc:	mpb <mpb.mail@...il.com>, netdev@...r.kernel.org
Subject: Re: [PATCH v2] socket: don't return uninitialized addresses on
 concurrent socket shutdown

On Sat, 2013-11-16 at 06:48 +0100, Hannes Frederic Sowa wrote:
> If a blocking read waits on a socket which gets concurrently shut down we
> return 0 as error and so indicate success to the socket functions which
> thus copy an uninitialized stack allocated address back to the user.
> Fix this by clearing the 128 byte size (on x86-64) address first.
> 
> This patch fixes the problem for recvfrom, recvmsg and recvmmsg.
> 
> Reported-by: mpb <mpb.mail@...il.com>
> Signed-off-by: Hannes Frederic Sowa <hannes@...essinduktion.org>
> ---

Are you clearing 128 bytes on every recvfrom() system call, just in case
of this shutdown() issue ?

Can't we avoid this overhead ?

msg.msg_namelen should be set to 0 in this case.



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