Subject: CVE-2024-47704: drm/amd/display: Check link_res->hpo_dp_link_enc before using it

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

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

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

drm/amd/display: Check link_res->hpo_dp_link_enc before using it

[WHAT & HOW]
Functions dp_enable_link_phy and dp_disable_link_phy can pass link_res
without initializing hpo_dp_link_enc and it is necessary to check for
null before dereferencing.

This fixes 2 FORWARD_NULL issues reported by Coverity.

The Linux kernel CVE team has assigned CVE-2024-47704 to this issue.

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

	Fixed in 6.6.55 with commit be2ca7a2c156
	Fixed in 6.10.14 with commit 530e29452b95
	Fixed in 6.11.2 with commit 0508a4e95ac1
	Fixed in 6.12-rc1 with commit 0beca868cde8

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-2024-47704
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/gpu/drm/amd/display/dc/link/hwss/link_hwss_hpo_dp.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/be2ca7a2c1561390d28bf2f92654d819659ba510
	https://git.kernel.org/stable/c/530e29452b955c30cf2102fa4d07420dc6e0c953
	https://git.kernel.org/stable/c/0508a4e95ac1aefd851ceb97ea050d8abb93262c
	https://git.kernel.org/stable/c/0beca868cde8742240cd0038141c30482d2b7eb8