In the Linux kernel, the following vulnerability has been resolved: net: ravb: serialize PTP clock teardown ravb_ptp_interrupt() can race

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

net: ravb: serialize PTP clock teardown

ravb_ptp_interrupt() can race with ravb_ptp_stop() and pass the clock to
ptp_clock_event() while ptp_clock_unregister() is freeing it. This can
lead to a use-after-free.

Use READ_ONCE() and WRITE_ONCE() for lockless access to the clock pointer.
Atomically detach it with xchg() before disabling PTP interrupts, then
synchronize all IRQs which can invoke ravb_ptp_interrupt() before
unregistering the detached clock.

A handler which read the old pointer completes before the clock is
unregistered, while later handlers read NULL and skip the event.