Subject: CVE-2024-27027: dpll: fix dpll_xa_ref_*_del() for multiple registrations

From: Greg Kroah-Hartman <[email-masked]>

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

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

dpll: fix dpll_xa_ref_*_del() for multiple registrations

Currently, if there are multiple registrations of the same pin on the
same dpll device, following warnings are observed:
WARNING: CPU: 5 PID: 2212 at drivers/dpll/dpll_core.c:143 dpll_xa_ref_pin_del.isra.0+0x21e/0x230
WARNING: CPU: 5 PID: 2212 at drivers/dpll/dpll_core.c:223 __dpll_pin_unregister+0x2b3/0x2c0

The problem is, that in both dpll_xa_ref_dpll_del() and
dpll_xa_ref_pin_del() registration is only removed from list in case the
reference count drops to zero. That is wrong, the registration has to
be removed always.

To fix this, remove the registration from the list and free
it unconditionally, instead of doing it only when the ref reference
counter reaches zero.

The Linux kernel CVE team has assigned CVE-2024-27027 to this issue.

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

	Issue introduced in 6.7 with commit 9431063ad323 and fixed in 6.7.11 with commit 769324eb3514
	Issue introduced in 6.7 with commit 9431063ad323 and fixed in 6.8.2 with commit b27e32e9367d
	Issue introduced in 6.7 with commit 9431063ad323 and fixed in 6.9 with commit b446631f355e

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-2024-27027
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/dpll/dpll_core.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/769324eb35143462542cdb15483cdaf4877bf661
	https://git.kernel.org/stable/c/b27e32e9367dac024cd6f61f22655714f483fd67
	https://git.kernel.org/stable/c/b446631f355ece73b13c311dd712c47381a23172