A Comprehensive Analysis of the GPL Issues With the Red Hat Enterprise Linux (RHEL) Business Model
sfconservancy.org
This article was originally published primarily as a response to IBM's Red Hat's change to no longer publish complete, corresponding source (CCS) for RHEL and the prior discontinuation of CentOS Linux (which are related events, as described below). We hope that this will serve as a comprehensive document that discusses the history of Red Hat's RHEL business model, the related source code provisioning, and the GPL compliance issues with RHEL.

The Software Freedom Conservancy issued a statement/report on the state of RHEL's GPL adherence. It seems it hasn't been a recent issue with them, and has gotten worse. Though, it is currently still undecided/unknown if RHEL's most recent actions fully violate the GPL or not.