team: check return value of team_get_port_by_index_rcu() for NULL

team_get_port_by_index_rcu() might return NULL due to race between port
removal and skb tx path. Panic is easily triggeable when txing packets
and adding/removing port in a loop.

introduced by commit 3d249d4ca "net: introduce ethernet teaming device"
and commit 753f993911b "team: introduce random mode" (for random mode)

Signed-off-by: Jiri Pirko <jiri@resnulli.us>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 2 insertions, 0 deletions

diff --git a/drivers/net/team/team_mode_random.c b/drivers/net/team/team_mode_random.c
index 5ca14d463ba7..7f032e211343 100644
--- a/drivers/net/team/team_mode_random.c
+++ b/drivers/net/team/team_mode_random.c
@@ -28,6 +28,8 @@ static bool rnd_transmit(struct team *team, struct sk_buff *skb)
 
         port_index = random_N(team->en_port_count);
         port = team_get_port_by_index_rcu(team, port_index);
+        if (unlikely(!port))
+                goto drop;
         port = team_get_first_port_txable_rcu(team, port);
         if (unlikely(!port))
                 goto drop;