linux-cve-announce - CVE-2026-23039: drm/gud: fix NULL fb and crtc dereferences on USB disconnect

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Message-ID: <2026013122-CVE-2026-23039-be18@gregkh>
Date: Sat, 31 Jan 2026 12:44:39 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2026-23039: drm/gud: fix NULL fb and crtc dereferences on USB disconnect

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

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

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

drm/gud: fix NULL fb and crtc dereferences on USB disconnect

On disconnect drm_atomic_helper_disable_all() is called which
sets both the fb and crtc for a plane to NULL before invoking a commit.

This causes a kernel oops on every display disconnect.

Add guards for those dereferences.

The Linux kernel CVE team has assigned CVE-2026-23039 to this issue.


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

	Issue introduced in 6.18 with commit 73cfd166e045769a1b42d36897accaa6e06b8102 and fixed in 6.18.7 with commit a255ec07f91d4c73a361a28b7a3d82f5710245f1
	Issue introduced in 6.18 with commit 73cfd166e045769a1b42d36897accaa6e06b8102 and fixed in 6.19-rc6 with commit dc2d5ddb193e363187bae2ad358245642d2721fb

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-2026-23039
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/gud/gud_pipe.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/a255ec07f91d4c73a361a28b7a3d82f5710245f1
	https://git.kernel.org/stable/c/dc2d5ddb193e363187bae2ad358245642d2721fb