CVE-2026-80991: net: ravb: serialize PTP clock teardown

CVE-2026-80991: net: ravb: serialize PTP clock teardown

[Greg Kroah-Hartman]

From: Greg Kroah-Hartman <gregkh@kernel.org>

Description
===========

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.

The Linux kernel CVE team has assigned CVE-2026-80991 to this issue.


Affected and fixed versions
===========================

	Issue introduced in 4.2 with commit a0d2f20650e81407d8e51ad2cbdc492861c74e9c and fixed in 6.12.109 with commit 695acb5534a9e366efb47b40c7487fc56488b09b
	Issue introduced in 4.2 with commit a0d2f20650e81407d8e51ad2cbdc492861c74e9c and fixed in 6.18.50 with commit 67a82e6f886beed0de8f8da08bb767e68fba952d
	Issue introduced in 4.2 with commit a0d2f20650e81407d8e51ad2cbdc492861c74e9c and fixed in 7.2.4 with commit 66b50c31419e7946e9aa325a468ad9b64c961a25
	Issue introduced in 4.2 with commit a0d2f20650e81407d8e51ad2cbdc492861c74e9c and fixed in 7.3-rc1 with commit 1cb9663789c5b7a12fcd419fcca6d6254c398252

Please see https://www.kernel.org for a full list of currently supported
kernel versions by the kernel community.

Unaffected versions might change over time as fixes are backported to
older supported kernel versions.  The official CVE entry at
	https://cve.org/CVERecord/?id=CVE-2026-80991
will be updated if fixes are backported, please check that for the most
up to date information about this issue.


Affected files
==============

The file(s) affected by this issue are:
	drivers/net/ethernet/renesas/ravb.h
	drivers/net/ethernet/renesas/ravb_main.c
	drivers/net/ethernet/renesas/ravb_ptp.c


Mitigation
==========

The Linux kernel CVE team recommends that you update to the latest
stable kernel version for this, and many other bugfixes.  Individual
changes are never tested alone, but rather are part of a larger kernel
release.  Cherry-picking individual commits is not recommended or
supported by the Linux kernel community at all.  If however, updating to
the latest release is impossible, the individual changes to resolve this
issue can be found at these commits:
	https://git.kernel.org/stable/c/695acb5534a9e366efb47b40c7487fc56488b09b
	https://git.kernel.org/stable/c/67a82e6f886beed0de8f8da08bb767e68fba952d
	https://git.kernel.org/stable/c/66b50c31419e7946e9aa325a468ad9b64c961a25
	https://git.kernel.org/stable/c/1cb9663789c5b7a12fcd419fcca6d6254c398252