batman-adv: initialize "struct batadv_tvlv_tt_vlan_data"->reserved field

KMSAN found uninitialized value at batadv_tt_prepare_tvlv_local_data()
[1], for commit ced7293 ("batman-adv: use CRC32C instead of CRC16
in TT code") inserted 'reserved' field into "struct batadv_tvlv_tt_data"
and commit 7ea7b4a ("batman-adv: make the TT CRC logic VLAN
specific") moved that field to "struct batadv_tvlv_tt_vlan_data" but left
that field uninitialized.

[1] https://syzkaller.appspot.com/bug?id=07f3e6dba96f0eb3cabab986adcd8a58b9bdbe9d

Reported-by: syzbot <[email protected]>
Tested-by: syzbot <[email protected]>
Signed-off-by: Tetsuo Handa <[email protected]>
Fixes: ced7293 ("batman-adv: use CRC32C instead of CRC16 in TT code")
Fixes: 7ea7b4a ("batman-adv: make the TT CRC logic VLAN specific")
Acked-by: Sven Eckelmann <[email protected]>
Signed-off-by: David S. Miller <[email protected]>

Author: Tetsuo Handa

net/batman-adv/translation-table.c

@@ -890,6 +890,7 @@ batadv_tt_prepare_tvlv_global_data(struct batadv_orig_node *orig_node,
 	hlist_for_each_entry(vlan, &orig_node->vlan_list, list) {
 		tt_vlan->vid = htons(vlan->vid);
 		tt_vlan->crc = htonl(vlan->tt.crc);
+		tt_vlan->reserved = 0;
 
 		tt_vlan++;
 	}
@@ -973,6 +974,7 @@ batadv_tt_prepare_tvlv_local_data(struct batadv_priv *bat_priv,
 
 		tt_vlan->vid = htons(vlan->vid);
 		tt_vlan->crc = htonl(vlan->tt.crc);
+		tt_vlan->reserved = 0;
 
 		tt_vlan++;
 	}