net: ieee802154: fix nl802154 del llsec dev

commit 3d1eac2f45585690d942cf47fd7fbd04093ebd1b upstream.

This patch fixes a nullpointer dereference if NL802154_ATTR_SEC_DEVICE is
not set by the user. If this is the case nl802154 will return -EINVAL.

Reported-by:  <syzbot+d946223c2e751d136c94@syzkaller.appspotmail.com>
Signed-off-by: Alexander Aring <aahringo@redhat.com>
Link: https://lore.kernel.org/r/20210221174321.14210-2-aahringo@redhat.com


Signed-off-by: Stefan Schmidt <stefan@datenfreihafen.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>