In the Linux kernel, the following vulnerability has been resolved:
posix-timers: Prevent RT livelock in itimer_delete()
itimer_delete() has a retry loop when the timer is concurrently expired. On non-RT kernels this just spin-waits until the timer callback has completed, except for posix CPU timers which have HAVE_POSIX_CPU_TIMERS_TASK_WORK enabled.
In that case and on RT kernels the existing task could live lock when preempting the task which does the timer delivery.
Replace spin_unlock() with an invocation of timer_wait_running() to handle it the same way as the other retry loops in the posix timer code.