From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752009AbaELBln (ORCPT ); Sun, 11 May 2014 21:41:43 -0400 Received: from 1wt.eu ([62.212.114.60]:34383 "EHLO 1wt.eu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751679AbaELBlj (ORCPT ); Sun, 11 May 2014 21:41:39 -0400 Message-Id: <20140512003203.347626109@1wt.eu> User-Agent: quilt/0.48-1 Date: Mon, 12 May 2014 02:33:05 +0200 From: Willy Tarreau To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Roman Gushchin , Eric Dumazet , "David S. Miller" , Willy Tarreau Subject: [ 065/143] net: check net.core.somaxconn sysctl values In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 2.6.32-longterm review patch. If anyone has any objections, please let me know. ------------------ From: Roman Gushchin [ Upstream commit 5f671d6b4ec3e6d66c2a868738af2cdea09e7509 ] 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 Signed-off-by: David S. Miller Signed-off-by: Willy Tarreau --- net/core/sysctl_net_core.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/net/core/sysctl_net_core.c b/net/core/sysctl_net_core.c index 7db1de0..e2eaf29 100644 --- a/net/core/sysctl_net_core.c +++ b/net/core/sysctl_net_core.c @@ -14,6 +14,9 @@ #include #include +static int zero = 0; +static int ushort_max = 65535; + static struct ctl_table net_core_table[] = { #ifdef CONFIG_NET { @@ -116,7 +119,9 @@ 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 }, { .ctl_name = 0 } }; -- 1.7.12.2.21.g234cd45.dirty