team: check return value of team_get_port_by_index_rcu() for NULL

[ Upstream commit 76c455decbbad31de21c727edb184a963f42b40b ]

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/net/team/team_mode_roundrobin.c b/drivers/net/team/team_mode_roundrobin.c
index 105135aa8f0586844927b641951087110a834cc1..041cc0a88715634b01ed189f1b537ca4e46724bf 100644 (file)
--- a/drivers/net/team/team_mode_roundrobin.c
+++ b/drivers/net/team/team_mode_roundrobin.c
@@ -52,6 +52,8 @@ static bool rr_transmit(struct team *team, struct sk_buff *skb)
 
        port_index = rr_priv(team)->sent_packets++ % team->en_port_count;
        port = team_get_port_by_index_rcu(team, port_index);
+       if (unlikely(!port))
+               goto drop;
        port = __get_first_port_up(team, port);
        if (unlikely(!port))
                goto drop;