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

commit 5182c2cf2a9bfb7f066ef0bdd2bb6330b94dd74e upstream.

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")
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/drivers/usb/serial/mos7840.c b/drivers/usb/serial/mos7840.c
index 643898943a154acda7785e30e2f4478ac2aadeaa..c868953a683935cf2e31ef52284f2c1dc8d798b0 100644 (file)
--- a/drivers/usb/serial/mos7840.c
+++ b/drivers/usb/serial/mos7840.c
@@ -1058,6 +1058,7 @@ 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,
@@ -2385,7 +2386,8 @@ static int mos7840_startup(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;
        }