Security with io_uring is great these days. Many years ago it moved away from the original architecture that led to several security issues; its current architecture is no more prone to security issues than any other part of the kernel.

For context, the original architecture involved having privileged kernel-side offload processing that had to carefully drop privileges each time it did something on behalf of the userspace process. As you can imagine, that fail-insecure architecture was heavily prone to security holes.

io_uring got rid of that architecture years ago, in favor of running with the permissions of the userspace process. With that change, there's no longer any reason to consider io_uring any less secure than the rest of the kernel.

wasn't the main issue about the asynchronous nature of the calls?