net: openvswitch: fix possible memory leak in ovs_meter_cmd_set()

old_meter needs to be free after it is detached regardless of whether
the new meter is successfully attached.

Fixes: c7c4c44 ("net: openvswitch: expand the meters supported number")
Signed-off-by: Hangyu Hua <hbh25y@gmail.com>
Acked-by: Eelco Chaudron <echaudro@redhat.com>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Author: HBh25Y

net/openvswitch/meter.c

@@ -449,7 +449,7 @@ static int ovs_meter_cmd_set(struct sk_buff *skb, struct genl_info *info)
 
 	err = attach_meter(meter_tbl, meter);
 	if (err)
-		goto exit_unlock;
+		goto exit_free_old_meter;
 
 	ovs_unlock();
 
@@ -472,6 +472,8 @@ static int ovs_meter_cmd_set(struct sk_buff *skb, struct genl_info *info)
 	genlmsg_end(reply, ovs_reply_header);
 	return genlmsg_reply(reply, info);
 
+exit_free_old_meter:
+	ovs_meter_free(old_meter);
 exit_unlock:
 	ovs_unlock();
 	nlmsg_free(reply);