--- sys/dev/usb2/serial/ugensa2.c	2008-11-22 14:39:51.000000000 +0800
+++ /var/current/mysrc/sys/dev/usb2/serial/ugensa2.c	2008-11-25 09:55:14.000000000 +0800
@@ -272,6 +272,9 @@
 	}
 	for (x = 0; x < cnt; x++) {
 		iface = usb2_get_iface(uaa->device, x);
+		if (iface == NULL)
+			/* should not happen */
+			continue;
 		if (iface->idesc->bInterfaceClass != UICLASS_VENDOR)
 			/* Not a serial port, most likely a SD reader */
 			continue;