From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Miller Subject: Re: [PATCH] net: check net.core.somaxconn sysctl values Date: Fri, 02 Aug 2013 15:19:15 -0700 (PDT) Message-ID: <20130802.151915.1964036907997678424.davem@davemloft.net> References: <20130801.141836.1104130035137318887.davem@davemloft.net> <1375454200-21303-1-git-send-email-klamm@yandex-team.ru> Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Cc: eric.dumazet@gmail.com, raise.sail@gmail.com, ebiederm@xmission.com, netdev@vger.kernel.org, linux-kernel@vger.kernel.org To: klamm@yandex-team.ru Return-path: In-Reply-To: <1375454200-21303-1-git-send-email-klamm@yandex-team.ru> Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org From: Roman Gushchin 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 > Reported-by: Changli Gao > Suggested-by: Eric Dumazet > Acked-by: Eric Dumazet Applied, thanks.