[PATCH 3.19.y-ckt 13/56] USB: mct_u232: add sanity checking in probe

From: Kamal Mostafa
Date: Tue Apr 12 2016 - 17:18:26 EST


3.19.8-ckt19 -stable review patch. If anyone has any objections, please let me know.

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

From: Oliver Neukum <oneukum@xxxxxxxx>

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@xxxxxxxx>
[johan: add error message ]
Signed-off-by: Johan Hovold <johan@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Kamal Mostafa <kamal@xxxxxxxxxxxxx>
---
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