Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933234AbbFPJ1a (ORCPT ); Tue, 16 Jun 2015 05:27:30 -0400 Received: from mail.kernel.org ([198.145.29.136]:55108 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932492AbbFPInB (ORCPT ); Tue, 16 Jun 2015 04:43:01 -0400 From: lizf@kernel.org To: stable@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Jiri Pirko , "David S. Miller" , Zefan Li Subject: [PATCH 3.4 052/172] team: fix possible null pointer dereference in team_handle_frame Date: Tue, 16 Jun 2015 16:35:06 +0800 Message-Id: <1434443826-4929-52-git-send-email-lizf@kernel.org> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1434443587-4599-1-git-send-email-lizf@kernel.org> References: <1434443587-4599-1-git-send-email-lizf@kernel.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2118 Lines: 60 From: Jiri Pirko 3.4.108-rc1 review patch. If anyone has any objections, please let me know. ------------------ commit 57e595631904c827cfa1a0f7bbd7cc9a49da5745 upstream. 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: Zefan Li --- drivers/net/team/team.c | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-) diff --git a/drivers/net/team/team.c b/drivers/net/team/team.c index d16800f..56299e9 100644 --- a/drivers/net/team/team.c +++ b/drivers/net/team/team.c @@ -39,9 +39,7 @@ 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) -- 1.9.1 -- 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/