From 55fde24a60ef618558fef13c2413afa5daf126df Mon Sep 17 00:00:00 2001 From: Jiri Pirko Date: Mon, 23 Feb 2015 14:02:54 +0100 Subject: [PATCH] team: fix possible null pointer dereference in team_handle_frame [ 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(-) diff --git a/drivers/net/team/team.c b/drivers/net/team/team.c index 12222290c802..44d4d2a5f6c8 100644 --- 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) -- 2.20.1