linux-cve-announce - CVE-2024-56775: drm/amd/display: Fix handling of plane refcount

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Message-ID: <2025010811-CVE-2024-56775-b841@gregkh>
Date: Wed,  8 Jan 2025 18:49:13 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: CVE-2024-56775: drm/amd/display: Fix handling of plane refcount

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

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

drm/amd/display: Fix handling of plane refcount

[Why]
The mechanism to backup and restore plane states doesn't maintain
refcount, which can cause issues if the refcount of the plane changes
in between backup and restore operations, such as memory leaks if the
refcount was supposed to go down, or double frees / invalid memory
accesses if the refcount was supposed to go up.

[How]
Cache and re-apply current refcount when restoring plane states.

The Linux kernel CVE team has assigned CVE-2024-56775 to this issue.


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

	Fixed in 6.12.4 with commit 8cb2f6793845f135b28361ba8e96901cae3e5790
	Fixed in 6.13-rc1 with commit 27227a234c1487cb7a684615f0749c455218833a

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-2024-56775
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/core/dc.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/8cb2f6793845f135b28361ba8e96901cae3e5790
	https://git.kernel.org/stable/c/27227a234c1487cb7a684615f0749c455218833a