net: ieee802154: forbid monitor for del llsec key

This patch forbids to del llsec key for monitor interfaces which we
don't support yet. Otherwise we will access llsec mib which isn't
initialized for monitors.
Signed-off-by: Alexander Aring <aahringo@redhat.com>
Link: https://lore.kernel.org/r/20210405003054.256017-6-aahringo@redhat.comSigned-off-by: Stefan Schmidt <stefan@datenfreihafen.org>

net/ieee802154/nl802154.c

@@ -1604,6 +1604,9 @@ static int nl802154_del_llsec_key(struct sk_buff *skb, struct genl_info *info)
 	struct nlattr *attrs[NL802154_KEY_ATTR_MAX + 1];
 	struct ieee802154_llsec_key_id id;
 
+	if (wpan_dev->iftype == NL802154_IFTYPE_MONITOR)
+		return -EOPNOTSUPP;
+
 	if (!info->attrs[NL802154_ATTR_SEC_KEY] ||
 	    nla_parse_nested_deprecated(attrs, NL802154_KEY_ATTR_MAX, info->attrs[NL802154_ATTR_SEC_KEY], nl802154_key_policy, info->extack))
 		return -EINVAL;