CVE-2026-90289: drm/amd/display: Resize MST HDCP per-connector arrays to 32

CVE-2026-90289: drm/amd/display: Resize MST HDCP per-connector arrays to 32

[Greg Kroah-Hartman]

From: Greg Kroah-Hartman <gregkh@kernel.org>

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

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

drm/amd/display: Resize MST HDCP per-connector arrays to 32

AMDGPU_DM_MAX_DISPLAY_INDEX is 31. It suggest a maximum number of
32 connectors. But the way it's used is like MAX_DISPLAY_COUNT.
Hence we're off by one with DRM core, which supports a max of 32
connectors.

Rename AMDGPU_DM_MAX_DISPLAY_INDEX to AMDGPU_DM_MAX_DISPLAY_COUNT
to match its actual use, and increase the size to 32 to match the
originally intended size.

The Linux kernel CVE team has assigned CVE-2026-90289 to this issue.


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

	Issue introduced in 6.3 with commit 82986fd631fa04bcedaefe11a6b3767601cbe84f and fixed in 7.2.6 with commit 0fa116a17b69a28712cdf209318e345b676d7f6c
	Issue introduced in 6.3 with commit 82986fd631fa04bcedaefe11a6b3767601cbe84f and fixed in 7.3-rc1 with commit 261e0fe4e2c99f687114b64b10b98db964b475f4
	Issue introduced in 5.15.128 with commit 99c444d3c3c43db354b253d9bfac081073dcb484
	Issue introduced in 6.1.47 with commit d90f97cb3821c47bdf773dcf6cade143773ec764

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-2026-90289
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_hdcp.c
	drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_hdcp.h


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/0fa116a17b69a28712cdf209318e345b676d7f6c
	https://git.kernel.org/stable/c/261e0fe4e2c99f687114b64b10b98db964b475f4