Subject: CVE-2024-43903: drm/amd/display: Add NULL check for 'afb' before dereferencing in amdgpu_dm_plane_handle_cursor_update

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

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

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

drm/amd/display: Add NULL check for 'afb' before dereferencing in amdgpu_dm_plane_handle_cursor_update

This commit adds a null check for the 'afb' variable in the
amdgpu_dm_plane_handle_cursor_update function. Previously, 'afb' was
assumed to be null, but was used later in the code without a null check.
This could potentially lead to a null pointer dereference.

Fixes the below:
drivers/gpu/drm/amd/amdgpu/../display/amdgpu_dm/amdgpu_dm_plane.c:1298 amdgpu_dm_plane_handle_cursor_update() error: we previously assumed 'afb' could be null (see line 1252)

The Linux kernel CVE team has assigned CVE-2024-43903 to this issue.

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

	Fixed in 6.1.105 with commit ce5d090af683
	Fixed in 6.6.46 with commit 94220b35aeba
	Fixed in 6.10.5 with commit 31a679a88010
	Fixed in 6.11 with commit 38e6f715b02b

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-2024-43903
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/amdgpu_dm/amdgpu_dm_plane.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/ce5d090af683137cb779ed7e3683839f9c778b35
	https://git.kernel.org/stable/c/94220b35aeba2b68da81deeefbb784d94eeb5c04
	https://git.kernel.org/stable/c/31a679a880102dee6e10985a7b1789af8dc328cc
	https://git.kernel.org/stable/c/38e6f715b02b572f74677eb2f29d3b4bc6f1ddff