CVE-2025-21655 Information

Description

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.

Reference

https://git.kernel.org/stable/c/6b63308c28987c6010b1180c72a6db4df6c68033 https://git.kernel.org/stable/c/8efff2aa2d95dc437ab67c5b4a9f1d3f367baa10 https://git.kernel.org/stable/c/a7085c3ae43b86d4b3d1b8275e6a67f14257e3b7 https://git.kernel.org/stable/c/c9a40292a44e78f71258b8522655bffaf5753bdb