Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760288Ab3GaOhm (ORCPT ); Wed, 31 Jul 2013 10:37:42 -0400 Received: from mail-pd0-f177.google.com ([209.85.192.177]:57738 "EHLO mail-pd0-f177.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756572Ab3GaOhk (ORCPT ); Wed, 31 Jul 2013 10:37:40 -0400 Message-ID: <1375281457.10515.98.camel@edumazet-glaptop> Subject: Re: [PATCH] net: check net.core.somaxconn sysctl values 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 Date: Wed, 31 Jul 2013 07:37:37 -0700 In-Reply-To: <51F917CF.7010905@yandex-team.ru> References: <51F917CF.7010905@yandex-team.ru> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.2.3-0ubuntu6 Content-Transfer-Encoding: 7bit Mime-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1778 Lines: 53 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/