Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759545Ab3GaOys (ORCPT ); Wed, 31 Jul 2013 10:54:48 -0400 Received: from forward-corp1e.mail.yandex.net ([77.88.60.199]:36385 "EHLO forward-corp1e.mail.yandex.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756422Ab3GaOyq (ORCPT ); Wed, 31 Jul 2013 10:54:46 -0400 Authentication-Results: smtpcorp4.mail.yandex.net; dkim=pass header.i=@yandex-team.ru Message-ID: <51F9252F.5030501@yandex-team.ru> Date: Wed, 31 Jul 2013 18:54:39 +0400 From: Roman Gushchin User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130623 Thunderbird/17.0.7 MIME-Version: 1.0 To: linux-kernel@vger.kernel.org Subject: FYI: Re: [PATCH] net: check net.core.somaxconn sysctl values References: <1375281457.10515.98.camel@edumazet-glaptop> In-Reply-To: <1375281457.10515.98.camel@edumazet-glaptop> X-Forwarded-Message-Id: <1375281457.10515.98.camel@edumazet-glaptop> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2146 Lines: 65 -------- Original Message -------- Subject: Re: [PATCH] net: check net.core.somaxconn sysctl values Date: Wed, 31 Jul 2013 07:37:37 -0700 From: Eric Dumazet To: Roman Gushchin CC: David S. Miller , raise.sail@gmail.com, ebiederm@xmission.com, netdev@vger.kernel.org, linux-kernel@vger.kernel.org On Wed, 2013-07-31 at 17:57 +0400, Roman Gushchin wrote: > 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" > > Signed-off-by: Roman Gushchin > --- > net/core/sysctl_net_core.c | 6 +++++- > 1 file changed, 5 insertions(+), 1 deletion(-) We had a discussion about this one month ago, as Changli Gao posted a patch. http://patchwork.ozlabs.org/patch/255460/ So proper credits would be nice ;) Based on a prior patch from Changli Gao Reported-by: Changli Gao Suggested-by: Eric Dumazet Acked-by: Eric Dumazet -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/