CVE-2025-21655

In the Linux kernel, the following vulnerability has been resolved:

io_uring/eventfd: ensure io_eventfd_signal() defers another RCU period

io_eventfd_do_signal() is invoked from an RCU callback, but when

dropping the reference to the io_ev_fd, it calls io_eventfd_free()

directly if the refcount drops to zero. This isn't correct, as any

potential freeing of the io_ev_fd should be deferred another RCU grace

period.

Just call io_eventfd_put() rather than open-code the dec-and-test and

free, which will correctly defer it another RCU grace period.