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

In the Linux kernel, the following vulnerability has been resolved: iouring/eventfd: ensure ioeventfdsignal defers another RCU period ioeventfddosignal is invoked from an RCU callback, but when dropping the reference to the ioevfd, it calls ioeventfdfree directly if the refcount drops to zero. Th...

DEBIAN-CVE-2025-21655

In the Linux kernel, the following vulnerability has been resolved: iouring/eventfd: ensure ioeventfdsignal defers another RCU period ioeventfddosignal is invoked from an RCU callback, but when dropping the reference to the ioevfd, it calls ioeventfdfree directly if the refcount drops to zero. Th...

CVE-2025-21655

CVE-2025-21655 affects the Linux kernel io_uring/eventfd path. The root cause is that io_eventfd_do_signal() frees an io_ev_fd immediately when the refcount drops to zero, instead of deferring to a subsequent RCU grace period. The fix defers freeing by calling io_eventfd_put() (replacing the inli...