From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754820AbaD1Bbr (ORCPT ); Sun, 27 Apr 2014 21:31:47 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:42840 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752168AbaD1B3V (ORCPT ); Sun, 27 Apr 2014 21:29:21 -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, "Hannes Frederic Sowa" , "Jan Stancek" , "David S. Miller" , "=?UTF-8?q?Linus=20L=C3=BCssing?=" Date: Mon, 28 Apr 2014 02:11:21 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.2 02/94] bridge: multicast: add sanity check for query source addresses In-Reply-To: X-SA-Exim-Connect-IP: 192.168.4.249 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 3.2.58-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Linus Lüssing [ Upstream commit 6565b9eeef194afbb3beec80d6dd2447f4091f8c ] MLD queries are supposed to have an IPv6 link-local source address according to RFC2710, section 4 and RFC3810, section 5.1.14. This patch adds a sanity check to ignore such broken MLD queries. Without this check, such malformed MLD queries can result in a denial of service: The queries are ignored by any MLD listener therefore they will not respond with an MLD report. However, without this patch these malformed MLD queries would enable the snooping part in the bridge code, potentially shutting down the according ports towards these hosts for multicast traffic as the bridge did not learn about these listeners. Reported-by: Jan Stancek Signed-off-by: Linus Lüssing Reviewed-by: Hannes Frederic Sowa Signed-off-by: David S. Miller Signed-off-by: Ben Hutchings --- net/bridge/br_multicast.c | 6 ++++++ 1 file changed, 6 insertions(+) --- a/net/bridge/br_multicast.c +++ b/net/bridge/br_multicast.c @@ -1138,6 +1138,12 @@ static int br_ip6_multicast_query(struct br_multicast_query_received(br, port, !ipv6_addr_any(&ip6h->saddr)); + /* RFC2710+RFC3810 (MLDv1+MLDv2) require link-local source addresses */ + if (!(ipv6_addr_type(&ip6h->saddr) & IPV6_ADDR_LINKLOCAL)) { + err = -EINVAL; + goto out; + } + if (skb->len == sizeof(*mld)) { if (!pskb_may_pull(skb, sizeof(*mld))) { err = -EINVAL;