Linux Kernel 5.4.220-5.4.263 - File Reference Cycle via io_uring Socket Transmission
In the Linux kernel, the following vulnerability has been resolved:
io_uring/af_unix: disable sending io_uring over sockets
File reference cycles have caused lots of problems for io_uring
in the past, and it still doesn't work exactly right and races with
unix_stream_read_generic(). The safest fix would be to completely
disallow sending io_uring files via sockets via SCM_RIGHT, so there
are no possible cycles invloving registered files and thus rendering
SCM accounting on the io_uring side unnecessary.