[media] usbvision fix overflow of interfaces array

This fixes the crash reported in:
http://seclists.org/bugtraq/2015/Oct/35
The interface number needs a sanity check.

Signed-off-by: Oliver Neukum <oneukum@suse.com>
Cc: Vladis Dronov <vdronov@redhat.com>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>

1 files changed, 7 insertions, 0 deletions

diff --git a/drivers/media/usb/usbvision/usbvision-video.c b/drivers/media/usb/usbvision/usbvision-video.c
index 4aa46caf7e22..3089d640c82d 100644
--- a/drivers/media/usb/usbvision/usbvision-video.c
+++ b/drivers/media/usb/usbvision/usbvision-video.c
@@ -1461,6 +1461,13 @@ static int usbvision_probe(struct usb_interface *intf,
         printk(KERN_INFO "%s: %s found\n", __func__,
                                 usbvision_device_data[model].model_string);
 
+        /*
+         * this is a security check.
+         * an exploit using an incorrect bInterfaceNumber is known
+         */
+        if (ifnum >= USB_MAXINTERFACES || !dev->actconfig->interface[ifnum])
+                return -ENODEV;
+
         if (usbvision_device_data[model].interface >= 0)
                 interface = &dev->actconfig->interface[usbvision_device_data[model].interface]->altsetting[0];
         else