Subject: CVE-2024-26648: drm/amd/display: Fix variable deferencing before NULL check in edp_setup_replay()

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

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

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

drm/amd/display: Fix variable deferencing before NULL check in edp_setup_replay()

In edp_setup_replay(), 'struct dc *dc' & 'struct dmub_replay *replay'
was dereferenced before the pointer 'link' & 'replay' NULL check.

Fixes the below:
drivers/gpu/drm/amd/amdgpu/../display/dc/link/protocols/link_edp_panel_control.c:947 edp_setup_replay() warn: variable dereferenced before check 'link' (see line 933)

The Linux kernel CVE team has assigned CVE-2024-26648 to this issue.

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

	Fixed in 6.6.15 with commit 22ae604aea14
	Fixed in 6.7.3 with commit c02d257c6541
	Fixed in 6.8 with commit 7073934f5d73

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-2024-26648
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/protocols/link_edp_panel_control.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/22ae604aea14756954e1c00ae653e34d2afd2935
	https://git.kernel.org/stable/c/c02d257c654191ecda1dc1af6875d527e85310e7
	https://git.kernel.org/stable/c/7073934f5d73f8b53308963cee36f0d389ea857c