net: ieee802154: stop dump llsec params for monitors

This patch stops dumping llsec params for monitors which we don't support
yet. Otherwise we will access llsec mib which isn't initialized for
monitors.

Reported-by: syzbot+cde43a581a8e5f317bc2@syzkaller.appspotmail.com
Signed-off-by: Alexander Aring <aahringo@redhat.com>
Link: https://lore.kernel.org/r/20210405003054.256017-16-aahringo@redhat.com
Signed-off-by: Stefan Schmidt <stefan@datenfreihafen.org>

net/ieee802154/nl802154.c

@@ -820,8 +820,13 @@ nl802154_send_iface(struct sk_buff *msg, u32 portid, u32 seq, int flags,
 		goto nla_put_failure;
 
 #ifdef CONFIG_IEEE802154_NL802154_EXPERIMENTAL
+	if (wpan_dev->iftype == NL802154_IFTYPE_MONITOR)
+		goto out;
+
 	if (nl802154_get_llsec_params(msg, rdev, wpan_dev) < 0)
 		goto nla_put_failure;
+
+out:
 #endif /* CONFIG_IEEE802154_NL802154_EXPERIMENTAL */
 
 	genlmsg_end(msg, hdr);