Describe CVE-2021-47123.
What is CVE-2021-47123?
In the Linux kernel, the following vulnerability has been resolved:

io_uring: fix ltout double free on completion race

Always remove linked timeout on io_link_timeout_fn() from the master
request link list, otherwise we may get use-after-free when first
io_link_timeout_fn() puts linked timeout in the fail path, and then
will be found and put on master's free..