media: uvcvideo: Prevent heap overflow when accessing mapped controls

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>
[bwh: Backported to 3.2: adjust filename]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/drivers/media/video/uvc/uvc_ctrl.c b/drivers/media/video/uvc/uvc_ctrl.c
index 254d32688843bdc3f0a38a782e13fef2ec8d5a18..47c3a557e3c1c8355e8cb4e17b605603d421d870 100644 (file)
--- a/drivers/media/video/uvc/uvc_ctrl.c
+++ b/drivers/media/video/uvc/uvc_ctrl.c
@@ -1698,6 +1698,13 @@ int uvc_ctrl_add_mapping(struct uvc_video_chain *chain,
                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', "