USB: serial: cyberjack: fix NULL-deref at open

commit 3dca0111 upstream.

Fix NULL-pointer dereference when clearing halt at open should the device
lack a bulk-out endpoint.

Unable to handle kernel NULL pointer dereference at virtual address 00000030
...
PC is at cyberjack_open+0x40/0x9c [cyberjack]

Fixes: 1da177e4 ("Linux-2.6.12-rc2")
Signed-off-by: Johan Hovold <johan@kernel.org>
[bwh: Backported to 3.2: add this check to the existing
 usb_serial_driver::attach implementation]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

drivers/usb/serial/cyberjack.c

@@ -122,6 +122,9 @@ static int cyberjack_startup(struct usb_serial *serial)
 
 	dbg("%s", __func__);
 
+	if (serial->num_bulk_out < serial->num_ports)
+		return -ENODEV;
+
 	/* allocate the private data structure */
 	priv = kmalloc(sizeof(struct cyberjack_private), GFP_KERNEL);
 	if (!priv)