CVE-2022-49229: ptp: unregister virtual clocks when unregistering physical clock.

CVE-2022-49229: ptp: unregister virtual clocks when unregistering physical clock.

[Greg Kroah-Hartman]

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

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

ptp: unregister virtual clocks when unregistering physical clock.

When unregistering a physical clock which has some virtual clocks,
unregister the virtual clocks with it.

This fixes the following oops, which can be triggered by unloading
a driver providing a PTP clock when it has enabled virtual clocks:

BUG: unable to handle page fault for address: ffffffffc04fc4d8
Oops: 0000 [#1] PREEMPT SMP NOPTI
RIP: 0010:ptp_vclock_read+0x31/0xb0
Call Trace:
 timecounter_read+0xf/0x50
 ptp_vclock_refresh+0x2c/0x50
 ? ptp_clock_release+0x40/0x40
 ptp_aux_kworker+0x17/0x30
 kthread_worker_fn+0x9b/0x240
 ? kthread_should_park+0x30/0x30
 kthread+0xe2/0x110
 ? kthread_complete_and_exit+0x20/0x20
 ret_from_fork+0x22/0x30

The Linux kernel CVE team has assigned CVE-2022-49229 to this issue.


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

	Issue introduced in 5.14 with commit 73f37068d540eba5f93ba3a0019bf479d35ebd76 and fixed in 5.15.33 with commit b2dea2a696d09163da4cd33cb598ce1f73e86597
	Issue introduced in 5.14 with commit 73f37068d540eba5f93ba3a0019bf479d35ebd76 and fixed in 5.16.19 with commit 9c796a57cbb5daf124a665689f0b2bc9262e0ced
	Issue introduced in 5.14 with commit 73f37068d540eba5f93ba3a0019bf479d35ebd76 and fixed in 5.17.2 with commit c49eafe6249f844c26f9866886cc6719d81762df
	Issue introduced in 5.14 with commit 73f37068d540eba5f93ba3a0019bf479d35ebd76 and fixed in 5.18 with commit bfcbb76b0f595ea9ede9f7a218086fef85242f10

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-2022-49229
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/ptp/ptp_clock.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/b2dea2a696d09163da4cd33cb598ce1f73e86597
	https://git.kernel.org/stable/c/9c796a57cbb5daf124a665689f0b2bc9262e0ced
	https://git.kernel.org/stable/c/c49eafe6249f844c26f9866886cc6719d81762df
	https://git.kernel.org/stable/c/bfcbb76b0f595ea9ede9f7a218086fef85242f10