From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751853AbaHDDjW (ORCPT ); Sun, 3 Aug 2014 23:39:22 -0400 Received: from szxga02-in.huawei.com ([119.145.14.65]:31577 "EHLO szxga02-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751360AbaHDDjV (ORCPT ); Sun, 3 Aug 2014 23:39:21 -0400 From: To: , , , , , , , CC: , , Chunhe Li Subject: [PATCH net/next] bridge:Add rcu read lock when delete br port Date: Mon, 4 Aug 2014 11:37:56 +0800 Message-ID: <1407123476-9720-1-git-send-email-lichunhe@huawei.com> X-Mailer: git-send-email 1.9.2.msysgit.0 MIME-Version: 1.0 Content-Type: text/plain X-Originating-IP: [10.177.26.106] X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Chunhe Li In the br_hanle_frame function has a bug, when the bridge receive packets which go througth the br_handle_frame, get the net_bridge_port pointer "p", but don't check NULL pointer to use it. If somebody delete the bridge port at the same time, will call a NULL pointer, trigger kernel panic. I see the del_nbp comments, call del_nbp should via RCU, but the caller don't do this. following steps will make bug happened 1.start vm and add the vm interface to a bridge br0,for example, brctl addbr br0 tap0 2.configuer vm interface and br0 same ip subnet, vm ping br0. 3.add and delete the vm interface port for endless loop. Signed-off-by: Chunhe Li --- net/bridge/br_if.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/net/bridge/br_if.c b/net/bridge/br_if.c index 3eca3fd..91c611d 100644 --- a/net/bridge/br_if.c +++ b/net/bridge/br_if.c @@ -274,9 +274,11 @@ void br_dev_delete(struct net_device *dev, struct list_head *head) struct net_bridge *br = netdev_priv(dev); struct net_bridge_port *p, *n; + rcu_read_lock(); list_for_each_entry_safe(p, n, &br->port_list, list) { del_nbp(p); } + rcu_read_unlock(); br_fdb_delete_by_port(br, NULL, 1); @@ -550,7 +552,9 @@ int br_del_if(struct net_bridge *br, struct net_device *dev) * there still maybe an alternate path for netconsole to use; * therefore there is no reason for a NETDEV_RELEASE event. */ + rcu_read_lock(); del_nbp(p); + rcu_read_unlock(); spin_lock_bh(&br->lock); changed_addr = br_stp_recalculate_bridge_id(br); -- 1.9.2.0