Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754080Ab3HAJE3 (ORCPT ); Thu, 1 Aug 2013 05:04:29 -0400 Received: from forward-corp1e.mail.yandex.net ([77.88.60.199]:52453 "EHLO forward-corp1e.mail.yandex.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751604Ab3HAJE0 (ORCPT ); Thu, 1 Aug 2013 05:04:26 -0400 Authentication-Results: smtpcorp4.mail.yandex.net; dkim=pass header.i=@yandex-team.ru Message-ID: <51FA2490.4020905@yandex-team.ru> Date: Thu, 01 Aug 2013 13:04:16 +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: David Miller CC: eric.dumazet@gmail.com, raise.sail@gmail.com, ebiederm@xmission.com, netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] net: check net.core.somaxconn sysctl values References: <51F917CF.7010905@yandex-team.ru> <20130731.171019.1991802407661623893.davem@davemloft.net> In-Reply-To: <20130731.171019.1991802407661623893.davem@davemloft.net> Content-Type: text/plain; charset=ISO-8859-1; 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: 2806 Lines: 92 On 01.08.2013 04:10, David Miller wrote: > From: Roman Gushchin > Date: Wed, 31 Jul 2013 17:57:35 +0400 > >> --- >> net/core/sysctl_net_core.c | 6 +++++- >> 1 file changed, 5 insertions(+), 1 deletion(-) >> >> diff --git a/net/core/sysctl_net_core.c b/net/core/sysctl_net_core.c >> index cfdb46a..2ff093b 100644 >> --- a/net/core/sysctl_net_core.c >> +++ b/net/core/sysctl_net_core.c >> @@ -20,7 +20,9 @@ > > This patch is against old sources, please respin it against the current > tree. > > Thanks. > net: check net.core.somaxconn sysctl values 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 --- net/core/sysctl_net_core.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/net/core/sysctl_net_core.c b/net/core/sysctl_net_core.c index 6609686..7c37dcd 100644 --- a/net/core/sysctl_net_core.c +++ b/net/core/sysctl_net_core.c @@ -21,7 +21,9 @@ #include #include +static int zero = 0; static int one = 1; +static int ushort_max = USHRT_MAX; #ifdef CONFIG_RPS static int rps_sock_flow_sysctl(struct ctl_table *table, int write, @@ -339,7 +341,9 @@ static struct ctl_table netns_core_table[] = { .data = &init_net.core.sysctl_somaxconn, .maxlen = sizeof(int), .mode = 0644, - .proc_handler = proc_dointvec + .extra1 = &zero, + .extra2 = &ushort_max, + .proc_handler = proc_dointvec_minmax }, { } }; -- 1.8.1.2 -- 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/