Nastia Liukin didn't seem too upset to hear convicted child molester Larry Nassar was attacked in prison by another inmate ... telling TMZ Sports that was "karma."
The ex-Team USA gymnast -- who's friends with several Nassar victims including McKayla Maroney and Aly Raisman -- found justice in Larry's prison assault ... shrugging her shoulders at the news.
FYI ... HBO just picked up the rights to a Nassar documentary that will unveil what female gymnasts had to endure at the hands of the team doctor .