From f7a3aa353011e38e119adebd845b38551587a26a Mon Sep 17 00:00:00 2001
From: Oliver Neukum <oneukum@suse.com>
Date: Thu, 17 Mar 2016 16:25:33 +0100
Subject: [PATCH] cypress_m8: add sanity checking

An attack using missing endpoints exists.
CVE-2016-3137

Signed-off-by: Oliver Neukum <ONeukum@suse.com>
CC: stable@vger.kernel.org

v1 - add sanity check
v2 - add error logging
v3 - correct error message
---
 drivers/usb/serial/cypress_m8.c | 11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/drivers/usb/serial/cypress_m8.c b/drivers/usb/serial/cypress_m8.c
index 01bf53392819..5e25443fe4ef 100644
--- a/drivers/usb/serial/cypress_m8.c
+++ b/drivers/usb/serial/cypress_m8.c
@@ -447,6 +447,11 @@ static int cypress_generic_port_probe(struct usb_serial_port *port)
 	struct usb_serial *serial = port->serial;
 	struct cypress_private *priv;
 
+	if (!port->interrupt_out_urb || !port->interrupt_in_urb) {
+		dev_err(&port->dev, "A 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_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,
-- 
2.5.0