The video_usercopy function in drivers/media/video/v4l2-ioctl.c in the Linux kernel before 2.6.39 relies on the count value of a v4l2_ext_controls data structure to determine a kmalloc size, which might allow local users to cause a denial of service (memory consumption) via a large value.
https://github.com/torvalds/linux/commit/fc0a80798576f80ca10b3f6c9c7097f12fd1d64e
http://www.securityfocus.com/bid/97986