CVE-2026-74732: drm/amd/display: Check for tg ops in dce110_set_avmute

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

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

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

drm/amd/display: Check for tg ops in dce110_set_avmute

Some older DCE timing generators do not implement is_tg_enabled in
their ops table. Calling it unconditionally when waiting for AV mute
frames causes a NULL pointer dereference on Southern Islands dGPUs
when turning the display off over HDMI.

Check that tg and the required ops exist before waiting for frames.

(cherry picked from commit 2686a0c0aaa07bec2e24131835cf27b5fd4935a5)

The Linux kernel CVE team has assigned CVE-2026-74732 to this issue.


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

	Fixed in 6.12.104 with commit 853c2d31408bd45dcf92d0eb1f06eb439a56cf04
	Fixed in 6.18.45 with commit d089f32d34f821c8f0ef23d5fcd77bd43c1b3b92
	Fixed in 7.1.9 with commit 5edbb409b0bc5001195f4b7cfca19122361211a1
	Fixed in 7.2 with commit 3141e3d61469bba2624a91c5e2407f110b33b29e

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-2026-74732
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/hwss/dce110/dce110_hwseq.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/853c2d31408bd45dcf92d0eb1f06eb439a56cf04
	https://git.kernel.org/stable/c/d089f32d34f821c8f0ef23d5fcd77bd43c1b3b92
	https://git.kernel.org/stable/c/5edbb409b0bc5001195f4b7cfca19122361211a1
	https://git.kernel.org/stable/c/3141e3d61469bba2624a91c5e2407f110b33b29e