bridge: mdb: fix leak on complete_info ptr on fail path

We currently get the following kmemleak report:
unreferenced object 0xffff8800039d9820 (size 32):
  comm "softirq", pid 0, jiffies 4295212383 (age 792.416s)
  hex dump (first 32 bytes):
    00 0c e0 03 00 88 ff ff ff 02 00 00 00 00 00 00  ................
    00 00 00 01 ff 11 00 02 86 dd 00 00 ff ff ff ff  ................
  backtrace:
    [<ffffffff8152b4aa>] kmemleak_alloc+0x4a/0xa0
    [<ffffffff811d8ec8>] kmem_cache_alloc_trace+0xb8/0x1c0
    [<ffffffffa0389683>] __br_mdb_notify+0x2a3/0x300 [bridge]
    [<ffffffffa038a0ce>] br_mdb_notify+0x6e/0x70 [bridge]
    [<ffffffffa0386479>] br_multicast_add_group+0x109/0x150 [bridge]
    [<ffffffffa0386518>] br_ip6_multicast_add_group+0x58/0x60 [bridge]
    [<ffffffffa0387fb5>] br_multicast_rcv+0x1d5/0xdb0 [bridge]
    [<ffffffffa037d7cf>] br_handle_frame_finish+0xcf/0x510 [bridge]
    [<ffffffffa03a236b>] br_nf_hook_thresh.part.27+0xb/0x10 [br_netfilter]
    [<ffffffffa03a3738>] br_nf_hook_thresh+0x48/0xb0 [br_netfilter]
    [<ffffffffa03a3fb9>] br_nf_pre_routing_finish_ipv6+0x109/0x1d0 [br_netfilter]
    [<ffffffffa03a4400>] br_nf_pre_routing_ipv6+0xd0/0x14c [br_netfilter]
    [<ffffffffa03a3c27>] br_nf_pre_routing+0x197/0x3d0 [br_netfilter]
    [<ffffffff814a2952>] nf_iterate+0x52/0x60
    [<ffffffff814a29bc>] nf_hook_slow+0x5c/0xb0
    [<ffffffffa037ddf4>] br_handle_frame+0x1a4/0x2c0 [bridge]

This happens when switchdev_port_obj_add() fails. This patch
frees complete_info object in the fail path.
Reviewed-by: Vallish Vaidyeshwara <vallish@amazon.com>
Signed-off-by: Eduardo Valentin <eduval@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/bridge/br_mdb.c

@@ -323,7 +323,8 @@ static void __br_mdb_notify(struct net_device *dev, struct net_bridge_port *p,
 			__mdb_entry_to_br_ip(entry, &complete_info->ip);
 			mdb.obj.complete_priv = complete_info;
 			mdb.obj.complete = br_mdb_complete;
-			switchdev_port_obj_add(port_dev, &mdb.obj);
+			if (switchdev_port_obj_add(port_dev, &mdb.obj))
+				kfree(complete_info);
 		}
 	} else if (port_dev && type == RTM_DELMDB) {
 		switchdev_port_obj_del(port_dev, &mdb.obj);