linux-kernel - Re: [PATCH] net: check net.core.somaxconn sysctl values

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Message-ID: <51FCD818.8040304@yandex-team.ru>
Date:	Sat, 03 Aug 2013 14:14:48 +0400
From:	Roman Gushchin <klamm@...dex-team.ru>
To:	David Miller <davem@...emloft.net>
CC:	eric.dumazet@...il.com, raise.sail@...il.com,
	ebiederm@...ssion.com, netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] net: check net.core.somaxconn sysctl values

On 03.08.2013 02:19, David Miller wrote:
> From: Roman Gushchin <klamm@...dex-team.ru>
> Date: Fri,  2 Aug 2013 18:36:40 +0400
>
>> It's possible to assign an invalid value to the net.core.somaxconn
>> sysctl variable, because there is no checks at all.
>>
>> The sk_max_ack_backlog field of the sock structure is defined as
>> unsigned short. Therefore, the backlog argument in inet_listen()
>> shouldn't exceed USHRT_MAX. The backlog argument in the listen() syscall
>> is truncated to the somaxconn value. So, the somaxconn value shouldn't
>> exceed 65535 (USHRT_MAX).
>> Also, negative values of somaxconn are meaningless.
>>
>> before:
>> $ sysctl -w net.core.somaxconn=256
>> net.core.somaxconn = 256
>> $ sysctl -w net.core.somaxconn=65536
>> net.core.somaxconn = 65536
>> $ sysctl -w net.core.somaxconn=-100
>> net.core.somaxconn = -100
>>
>> after:
>> $ sysctl -w net.core.somaxconn=256
>> net.core.somaxconn = 256
>> $ sysctl -w net.core.somaxconn=65536
>> error: "Invalid argument" setting key "net.core.somaxconn"
>> $ sysctl -w net.core.somaxconn=-100
>> error: "Invalid argument" setting key "net.core.somaxconn"
>>
>> Based on a prior patch from Changli Gao.
>>
>> Signed-off-by: Roman Gushchin <klamm@...dex-team.ru>
>> Reported-by: Changli Gao <xiaosuo@...il.com>
>> Suggested-by: Eric Dumazet <edumazet@...gle.com>
>> Acked-by: Eric Dumazet <edumazet@...gle.com>
>
> Applied, thanks.

Thank you!

Regards,
Roman

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