[PATCH 4.4 136/137] [media] usbvision: fix crash on detecting device with invalid configuration

[Greg Kroah-Hartman]

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

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

From: Vladis Dronov <vdro...@redhat.com>

commit fa52bd506f274b7619955917abfde355e3d19ffe upstream.

The usbvision driver crashes when a specially crafted usb device with invalid
number of interfaces or endpoints is detected. This fix adds checks that the
device has proper configuration expected by the driver.

Reported-by: Ralf Spenneberg <r...@spenneberg.net>
Signed-off-by: Vladis Dronov <vdro...@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mche...@osg.samsung.com>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>

---
 drivers/media/usb/usbvision/usbvision-video.c |   16 +++++++++++++++-
 1 file changed, 15 insertions(+), 1 deletion(-)

--- a/drivers/media/usb/usbvision/usbvision-video.c
+++ b/drivers/media/usb/usbvision/usbvision-video.c
@@ -1470,9 +1470,23 @@ static int usbvision_probe(struct usb_in
 
        if (usbvision_device_data[model].interface >= 0)
                interface = 
&dev->actconfig->interface[usbvision_device_data[model].interface]->altsetting[0];
-       else
+       else if (ifnum < dev->actconfig->desc.bNumInterfaces)
                interface = &dev->actconfig->interface[ifnum]->altsetting[0];
+       else {
+               dev_err(&intf->dev, "interface %d is invalid, max is %d\n",
+                   ifnum, dev->actconfig->desc.bNumInterfaces - 1);
+               ret = -ENODEV;
+               goto err_usb;
+       }
+
+       if (interface->desc.bNumEndpoints < 2) {
+               dev_err(&intf->dev, "interface %d has %d endpoints, but must"
+                   " have minimum 2\n", ifnum, interface->desc.bNumEndpoints);
+               ret = -ENODEV;
+               goto err_usb;
+       }
        endpoint = &interface->endpoint[1].desc;
+
        if (!usb_endpoint_xfer_isoc(endpoint)) {
                dev_err(&intf->dev, "%s: interface %d. has non-ISO endpoint!\n",
                    __func__, ifnum);