Going for the pipe spray is a kinda weird technique, and I'm honestly surprised that it worked. Usually just the fact that you are able to spray over the allocation at all isn't enough, and you also have to worry about your sprayed data containing additional pointers or things that also have to be valid.
I probably would have gone for turning the UaF into an type confusion style attack: if you spray more sockets you'll end up with two files, the original and the new one, that have aliased sk members, but the vsock code will incorrectly cast the new one to a `vsock_sock`. From there you can probably find some other socket type that puts controllable data over some field that vsock treats as a pointer or vice versa, and use it as both a kaslr leak and data-only r/w primitive.
I probably would have gone for turning the UaF into an type confusion style attack: if you spray more sockets you'll end up with two files, the original and the new one, that have aliased sk members, but the vsock code will incorrectly cast the new one to a `vsock_sock`. From there you can probably find some other socket type that puts controllable data over some field that vsock treats as a pointer or vice versa, and use it as both a kaslr leak and data-only r/w primitive.