The ZDI disclosure is rather vague, but I suspect this is a vendor-specific vulnerability and the speculation otherwise in the Ars Technica article is just wrong. There is no single "v4l2 driver" used by across all of Android - every device has its own v4l2 driver with its own implementation of the userland-facing v4l2 APIs, and vendors being what they are some of them are of pretty poor quality.