Data corruption or loss via unchecked virtio length

Buffer length validation failure in the Linux kernel before 5.13.4 allows an untrusted virtio device to cause data corruption or loss. The get_inbuf and control_work_handler paths assign the device-reported virtqueue length to buf->len without limiting it to buf->size, allowing later processing to trust a length larger than the buffer. Reachability requires an untrusted device, and the vendor states that no existing use case makes the robustness defect a security vulnerability.