[PATCH 4.4 57/66] media: uvcvideo: Prevent heap overflow when accessing mapped controls

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

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

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

From: Guenter Roeck <linux@roeck-us.net>

commit 7e09f7d5c790278ab98e5f2c22307ebe8ad6e8ba upstream.

The size of uvc_control_mapping is user controlled leading to a
potential heap overflow in the uvc driver. This adds a check to verify
the user provided size fits within the bounds of the defined buffer
size.

Originally-from: Richard Simmons <rssimmo@amazon.com>

Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/media/usb/uvc/uvc_ctrl.c |    7 +++++++
 1 file changed, 7 insertions(+)

--- a/drivers/media/usb/uvc/uvc_ctrl.c
+++ b/drivers/media/usb/uvc/uvc_ctrl.c
@@ -2001,6 +2001,13 @@ int uvc_ctrl_add_mapping(struct uvc_vide
 		goto done;
 	}
 
+	/* Validate the user-provided bit-size and offset */
+	if (mapping->size > 32 ||
+	    mapping->offset + mapping->size > ctrl->info.size * 8) {
+		ret = -EINVAL;
+		goto done;
+	}
+
 	list_for_each_entry(map, &ctrl->info.mappings, list) {
 		if (mapping->id == map->id) {
 			uvc_trace(UVC_TRACE_CONTROL, "Can't add mapping '%s', "