io_uring/af_unix: defer registered files gc to io_uring release

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: io_uring/af_unix: defer registered files gc to io_uring release Instead of putting io_uring's registered files in unix_gc() we want it to be done by io_uring itself. The trick here is to consider io_uring registered files for cycle detection but not actually putting them down. Because io_uring can't register other ring instances, this will remove all refs to the ring file triggering the ->release path and clean up with io_ring_ctx_free(). [axboe: add kerneldoc comment to skb, fold in skb leak fix]

References

• https://git.kernel.org/stable/c/04df9719df1865f6770af9bc7880874af0e594b2
• https://git.kernel.org/stable/c/c378c479c5175833bb22ff71974cda47d7b05401
• https://git.kernel.org/stable/c/813d8fe5d30388f73a21d3a2bf46b0a1fd72498c
• https://git.kernel.org/stable/c/b4293c01ee0d0ecdd3cb5801e13f62271144667a
• https://git.kernel.org/stable/c/75e94c7e8859e58aadc15a98cc9704edff47d4f2
• https://git.kernel.org/stable/c/0091bfc81741b8d3aeb3b7ab8636f911b2de6e80