From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753651AbcFEVxm (ORCPT ); Sun, 5 Jun 2016 17:53:42 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:43373 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753895AbcFEVxR (ORCPT ); Sun, 5 Jun 2016 17:53:17 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Greg Kroah-Hartman , Sven Eckelmann , Antonio Quartulli Subject: [PATCH 4.6 076/121] batman-adv: Fix double neigh_node_put in batadv_v_ogm_route_update Date: Sun, 5 Jun 2016 14:43:48 -0700 Message-Id: <20160605214420.040928849@linuxfoundation.org> X-Mailer: git-send-email 2.8.3 In-Reply-To: <20160605214417.708509043@linuxfoundation.org> References: <20160605214417.708509043@linuxfoundation.org> User-Agent: quilt/0.64 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 4.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Sven Eckelmann The router is put down twice when it was non-NULL and either orig_ifinfo is NULL afterwards or batman-adv receives a packet with the same sequence number. This will end up in a use-after-free when the batadv_neigh_node is removed because the reference counter ended up too early at 0. This patch is skipping netdev and is being sent directly to stable in accordance with David S. Miller[1]. The reason is that this patch applies only on linux-4.6 and not on linux-4.7/net because it was "accidentally" fixed by a refactoring commit (more details in [2]). It addresses a reference imbalance which systematically leads to a use-after-free and then a kernel crash. [1] https://www.mail-archive.com/b.a.t.m.a.n@lists.open-mesh.org/msg15258.html [2] https://www.mail-archive.com/b.a.t.m.a.n@lists.open-mesh.org/msg15252.html Fixes: 9323158ef9f4 ("batman-adv: OGMv2 - implement originators logic") Signed-off-by: Sven Eckelmann Signed-off-by: Antonio Quartulli Signed-off-by: Greg Kroah-Hartman --- Cheers, net/batman-adv/bat_v_ogm.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) --- a/net/batman-adv/bat_v_ogm.c +++ b/net/batman-adv/bat_v_ogm.c @@ -529,8 +529,10 @@ static void batadv_v_ogm_route_update(st goto out; } - if (router) + if (router) { batadv_neigh_node_put(router); + router = NULL; + } /* Update routes, and check if the OGM is from the best next hop */ batadv_v_ogm_orig_update(bat_priv, orig_node, neigh_node, ogm2,