USB: cypress_m8: add endpoint sanity check

commit c55aee1bf0e6b6feec8b2927b43f7a09a6d5f754 upstream.

An attack using missing endpoints exists.

CVE-2016-3137

Signed-off-by: Oliver Neukum <ONeukum@suse.com>
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/drivers/usb/serial/cypress_m8.c b/drivers/usb/serial/cypress_m8.c
index 10c30ad..8db2fb1 100644 (file)
--- a/drivers/usb/serial/cypress_m8.c
+++ b/drivers/usb/serial/cypress_m8.c
@@ -489,6 +489,11 @@ static int generic_startup(struct usb_serial *serial)
 
        dbg("%s - port %d", __func__, port->number);
 
+       if (!port->interrupt_out_urb || !port->interrupt_in_urb) {
+               dev_err(&port->dev, "required endpoint is missing\n");
+               return -ENODEV;
+       }
+
        priv = kzalloc(sizeof(struct cypress_private), GFP_KERNEL);
        if (!priv)
                return -ENOMEM;
@@ -658,12 +663,6 @@ static int cypress_open(struct tty_struct *tty, struct usb_serial_port *port)
                cypress_set_termios(tty, port, &priv->tmp_termios);
 
        /* setup the port and start reading from the device */
-       if (!port->interrupt_in_urb) {
-               dev_err(&port->dev, "%s - interrupt_in_urb is empty!\n",
-                       __func__);
-               return -1;
-       }
-
        usb_fill_int_urb(port->interrupt_in_urb, serial->dev,
                usb_rcvintpipe(serial->dev, port->interrupt_in_endpointAddress),
                port->interrupt_in_urb->transfer_buffer,