Commit 722243f1 authored Feb 23, 2015 by Jiri Pirko Committed by Sasha Levin Mar 14, 2015

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 <jiri@resnulli.us>
Fixes: 3d249d4c ("net: introduce ethernet teaming device")
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sasha.levin@oracle.com>

parent 53950010

drivers/net/team/team.c

+1 −3

Original line number	Diff line number	Diff line
		@@ -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)