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 <[email protected]>     # v2.6.19: 5c75633ef751
Signed-off-by: Johan Hovold <[email protected]>
---
 drivers/usb/serial/mos7840.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

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;
        }
-- 
2.10.2

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