Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756083Ab3JUJfB (ORCPT ); Mon, 21 Oct 2013 05:35:01 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:39261 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753062Ab3JUIuO (ORCPT ); Mon, 21 Oct 2013 04:50:14 -0400 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "Changli Gao" , "Eric Dumazet" , "Roman Gushchin" , "David S. Miller" Date: Mon, 21 Oct 2013 09:46:28 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.2 002/149] net: check net.core.somaxconn sysctl values In-Reply-To: X-SA-Exim-Connect-IP: 212.20.242.100 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2536 Lines: 77 3.2.52-rc1 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: Ben Hutchings --- 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 77a65f0..f0bdd36 100644 --- a/net/core/sysctl_net_core.c +++ b/net/core/sysctl_net_core.c @@ -19,6 +19,9 @@ #include #include +static int zero = 0; +static int ushort_max = USHRT_MAX; + #ifdef CONFIG_RPS static int rps_sock_flow_sysctl(ctl_table *table, int write, void __user *buffer, size_t *lenp, loff_t *ppos) @@ -192,7 +195,9 @@ 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 }, { } }; -- 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/