From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755505AbbCPOLo (ORCPT ); Mon, 16 Mar 2015 10:11:44 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:54598 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755398AbbCPOLj (ORCPT ); Mon, 16 Mar 2015 10:11:39 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Jiri Pirko , "David S. Miller" Subject: [PATCH 3.19 020/177] team: fix possible null pointer dereference in team_handle_frame Date: Mon, 16 Mar 2015 15:07:07 +0100 Message-Id: <20150316140814.006845357@linuxfoundation.org> X-Mailer: git-send-email 2.3.3 In-Reply-To: <20150316140813.085032723@linuxfoundation.org> References: <20150316140813.085032723@linuxfoundation.org> User-Agent: quilt/0.64 MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.19-stable review patch. If anyone has any objections, please let me know. ------------------ From: Jiri Pirko [ Upstream commit 57e595631904c827cfa1a0f7bbd7cc9a49da5745 ] Currently following race is possible in team: CPU0 CPU1 team_port_del team_upper_dev_unlink priv_flags &= ~IFF_TEAM_PORT team_handle_frame team_port_get_rcu team_port_exists priv_flags & IFF_TEAM_PORT == 0 return NULL (instead of port got from rx_handler_data) netdev_rx_handler_unregister The thing is that the flag is removed before rx_handler is unregistered. If team_handle_frame is called in between, team_port_exists returns 0 and team_port_get_rcu will return NULL. So do not check the flag here. It is guaranteed by netdev_rx_handler_unregister that team_handle_frame will always see valid rx_handler_data pointer. Signed-off-by: Jiri Pirko Fixes: 3d249d4ca7d0 ("net: introduce ethernet teaming device") Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- drivers/net/team/team.c | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-) --- a/drivers/net/team/team.c +++ b/drivers/net/team/team.c @@ -42,9 +42,7 @@ static struct team_port *team_port_get_rcu(const struct net_device *dev) { - struct team_port *port = rcu_dereference(dev->rx_handler_data); - - return team_port_exists(dev) ? port : NULL; + return rcu_dereference(dev->rx_handler_data); } static struct team_port *team_port_get_rtnl(const struct net_device *dev)