USB: serial: mos7840: fix another NULL-deref at open

Fix another NULL-pointer dereference at open should a malicious device
lack an interrupt-in endpoint.

Note that the driver has a broken check for an interrupt-in endpoint
which means that an interrupt URB has never even been submitted.

Fixes: 3f5429746d91 ("USB: Moschip 7840 USB-Serial Driver")
Cc: stable <stable@vger.kernel.org>	# v2.6.19: 5c75633ef751
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Johan Hovold <johan@kernel.org>

1 files changed, 3 insertions, 1 deletions

diff --git a/drivers/usb/serial/mos7840.c b/drivers/usb/serial/mos7840.c
index d1b92f582478..3821c53fcee9 100644
--- a/drivers/usb/serial/mos7840.c
+++ b/drivers/usb/serial/mos7840.c
@@ -1034,6 +1034,7 @@ static int mos7840_open(struct tty_struct *tty, struct usb_serial_port *port)
          * (can't set it up in mos7840_startup as the structures *
          * were not set up at that time.)                        */
         if (port0->open_ports == 1) {
+                /* FIXME: Buffer never NULL, so URB is not submitted. */
                 if (serial->port[0]->interrupt_in_buffer == NULL) {
                         /* set up interrupt urb */
                         usb_fill_int_urb(serial->port[0]->interrupt_in_urb,
@@ -2116,7 +2117,8 @@ static int mos7840_calc_num_ports(struct usb_serial *serial)
 static int mos7840_attach(struct usb_serial *serial)
 {
         if (serial->num_bulk_in < serial->num_ports ||
-                        serial->num_bulk_out < serial->num_ports) {
+                        serial->num_bulk_out < serial->num_ports ||
+                        serial->num_interrupt_in < 1) {
                 dev_err(&serial->interface->dev, "missing endpoints\n");
                 return -ENODEV;
         }