[PATCH 3.2 87/87] [media] usbvision: fix crash on detecting device with invalid configuration

[Ben Hutchings]

3.2.77-rc1 review patch.  If anyone has any objections, please let me know.

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

From: Vladis Dronov <vdronov@xxxxxxxxxx>

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 <ralf@xxxxxxxxxxxxxx>
Signed-off-by: Vladis Dronov <vdronov@xxxxxxxxxx>
Signed-off-by: Mauro Carvalho Chehab <mchehab@xxxxxxxxxxxxxxx>
[bwh: Backport to 3.2: adjust filename]
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
 drivers/media/video/usbvision/usbvision-video.c | 16 +++++++++++++++-
 1 file changed, 15 insertions(+), 1 deletion(-)

--- a/drivers/media/video/usbvision/usbvision-video.c
+++ b/drivers/media/video/usbvision/usbvision-video.c
@@ -1511,9 +1511,23 @@ static int __devinit usbvision_probe(str
 
 	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);