[PATCH 3.16.y-ckt 020/165] team: fix possible null pointer dereference in team_handle_frame

Luis Henriques luis.henriques at canonical.com
Wed Mar 25 13:59:53 UTC 2015

3.16.7-ckt9 -stable review patch.  If anyone has any objections, please let me know.


From: Jiri Pirko <jiri at resnulli.us>

commit 57e595631904c827cfa1a0f7bbd7cc9a49da5745 upstream.

Currently following race is possible in team:

CPU0                                        CPU1
                                                priv_flags &= ~IFF_TEAM_PORT
      priv_flags & IFF_TEAM_PORT == 0
    return NULL (instead of port got
                 from rx_handler_data)

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 at resnulli.us>
Fixes: 3d249d4ca7d0 ("net: introduce ethernet teaming device")
Signed-off-by: David S. Miller <davem at davemloft.net>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
 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 3dd334a29fcf..fa977f9c2e5f 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)

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