Subject: CVE-2023-52505: phy: lynx-28g: serialize concurrent phy_set_mode_ext() calls to shared registers

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

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

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

phy: lynx-28g: serialize concurrent phy_set_mode_ext() calls to shared registers

The protocol converter configuration registers PCC8, PCCC, PCCD
(implemented by the driver), as well as others, control protocol
converters from multiple lanes (each represented as a different
struct phy). So, if there are simultaneous calls to phy_set_mode_ext()
to lanes sharing the same PCC register (either for the "old" or for the
"new" protocol), corruption of the values programmed to hardware is
possible, because lynx_28g_rmw() has no locking.

Add a spinlock in the struct lynx_28g_priv shared by all lanes, and take
the global spinlock from the phy_ops :: set_mode() implementation. There
are no other callers which modify PCC registers.

The Linux kernel CVE team has assigned CVE-2023-52505 to this issue.

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

	Issue introduced in 5.18 with commit 8f73b37cf3fb and fixed in 6.1.59 with commit 6f901f8448c6
	Issue introduced in 5.18 with commit 8f73b37cf3fb and fixed in 6.5.8 with commit c2d7c79898b4
	Issue introduced in 5.18 with commit 8f73b37cf3fb and fixed in 6.6 with commit 139ad1143151

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-2023-52505
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/phy/freescale/phy-fsl-lynx-28g.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/6f901f8448c6b25ed843796b114471d2a3fc5dfb
	https://git.kernel.org/stable/c/c2d7c79898b427d263c64a4841987eec131f2d4e
	https://git.kernel.org/stable/c/139ad1143151a07be93bf741d4ea7c89e59f89ce