[4.2.y-ckt stable] Patch "USB: mct_u232: add sanity checking in probe" has been added to the 4.2.y-ckt tree

[Kamal Mostafa]

This is a note to let you know that I have just added a patch titled

    USB: mct_u232: add sanity checking in probe

to the linux-4.2.y-queue branch of the 4.2.y-ckt extended stable tree 
which can be found at:

    http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-4.2.y-queue

This patch is scheduled to be released in version 4.2.8-ckt8.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 4.2.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

---8<------------------------------------------------------------

>From 2a04711fab1c0d92e647486db394261a0772cfab Mon Sep 17 00:00:00 2001
From: Oliver Neukum <oneukum at suse.com>
Date: Thu, 31 Mar 2016 12:04:24 -0400
Subject: USB: mct_u232: add sanity checking in probe

commit 4e9a0b05257f29cf4b75f3209243ed71614d062e upstream.

An attack using the lack of sanity checking in probe is known. This
patch checks for the existence of a second port.

CVE-2016-3136

Signed-off-by: Oliver Neukum <ONeukum at suse.com>
[johan: add error message ]
Signed-off-by: Johan Hovold <johan at kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 drivers/usb/serial/mct_u232.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/serial/mct_u232.c b/drivers/usb/serial/mct_u232.c
index fd707d6..89726f7 100644
--- a/drivers/usb/serial/mct_u232.c
+++ b/drivers/usb/serial/mct_u232.c
@@ -376,14 +376,21 @@ static void mct_u232_msr_to_state(struct usb_serial_port *port,

 static int mct_u232_port_probe(struct usb_serial_port *port)
 {
+	struct usb_serial *serial = port->serial;
 	struct mct_u232_private *priv;

+	/* check first to simplify error handling */
+	if (!serial->port[1] || !serial->port[1]->interrupt_in_urb) {
+		dev_err(&port->dev, "expected endpoint missing\n");
+		return -ENODEV;
+	}
+
 	priv = kzalloc(sizeof(*priv), GFP_KERNEL);
 	if (!priv)
 		return -ENOMEM;

 	/* Use second interrupt-in endpoint for reading. */
-	priv->read_urb = port->serial->port[1]->interrupt_in_urb;
+	priv->read_urb = serial->port[1]->interrupt_in_urb;
 	priv->read_urb->context = port;

 	spin_lock_init(&priv->lock);
--
2.7.4