The AT_RANDOM bytes are designed to provide randomness to the loader when the program is loaded. I looked at glibc and it's using this for a random stack check canary (which is needed very early during dynamic loading), and not actually used for anything else.

glibc nulls out its internal pointer (_dl_random) after use so you can't easily get the pointer later, but of course it'd be a bad idea to try and use it.