[PATCH 4.4 060/210] USB: cypress_m8: add endpoint sanity check

[Greg Kroah-Hartman]

4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Oliver Neukum <oneukum@xxxxxxxx>

commit c55aee1bf0e6b6feec8b2927b43f7a09a6d5f754 upstream.

An attack using missing endpoints exists.

CVE-2016-3137

Signed-off-by: Oliver Neukum <ONeukum@xxxxxxxx>
Signed-off-by: Johan Hovold <johan@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/usb/serial/cypress_m8.c |   11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

--- a/drivers/usb/serial/cypress_m8.c
+++ b/drivers/usb/serial/cypress_m8.c
@@ -447,6 +447,11 @@ static int cypress_generic_port_probe(st
 	struct usb_serial *serial = port->serial;
 	struct cypress_private *priv;
 
+	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;
@@ -606,12 +611,6 @@ static int cypress_open(struct tty_struc
 		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,