From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: linux-cve-announce@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@kernel.org>
Subject: CVE-2026-43477: drm/i915/vrr: Configure VRR timings after enabling TRANS_DDI_FUNC_CTL
Date: Wed, 13 May 2026 17:08:45 +0200 [thread overview]
Message-ID: <2026051347-CVE-2026-43477-189e@gregkh> (raw)
From: Greg Kroah-Hartman <gregkh@kernel.org>
Description
===========
In the Linux kernel, the following vulnerability has been resolved:
drm/i915/vrr: Configure VRR timings after enabling TRANS_DDI_FUNC_CTL
Apparently ICL may hang with an MCE if we write TRANS_VRR_VMAX/FLIPLINE
before enabling TRANS_DDI_FUNC_CTL.
Personally I was only able to reproduce a hang (on an Dell XPS 7390
2-in-1) with an external display connected via a dock using a dodgy
type-C cable that made the link training fail. After the failed
link training the machine would hang. TGL seemed immune to the
problem for whatever reason.
BSpec does tell us to configure VRR after enabling TRANS_DDI_FUNC_CTL
as well. The DMC firmware also does the VRR restore in two stages:
- first stage seems to be unconditional and includes TRANS_VRR_CTL
and a few other VRR registers, among other things
- second stage is conditional on the DDI being enabled,
and includes TRANS_DDI_FUNC_CTL and TRANS_VRR_VMAX/VMIN/FLIPLINE,
among other things
So let's reorder the steps to match to avoid the hang, and
toss in an extra WARN to make sure we don't screw this up later.
BSpec: 22243
(cherry picked from commit 93f3a267c3dd4d811b224bb9e179a10d81456a74)
The Linux kernel CVE team has assigned CVE-2026-43477 to this issue.
Affected and fixed versions
===========================
Issue introduced in 6.16 with commit dda7dcd9da73c5327aef42b89f0519bb51e84217 and fixed in 6.18.20 with commit 8a7d29b8bda144d44e61df1b2705b1d4378f4e44
Issue introduced in 6.16 with commit dda7dcd9da73c5327aef42b89f0519bb51e84217 and fixed in 6.19.9 with commit bf9e3b6ffd76da38dd4961c65d80571b25bf10a5
Issue introduced in 6.16 with commit dda7dcd9da73c5327aef42b89f0519bb51e84217 and fixed in 7.0 with commit 237aab549676288d9255bb8dcc284738e56eaa31
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-2026-43477
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/i915/display/intel_display.c
drivers/gpu/drm/i915/display/intel_vrr.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/8a7d29b8bda144d44e61df1b2705b1d4378f4e44
https://git.kernel.org/stable/c/bf9e3b6ffd76da38dd4961c65d80571b25bf10a5
https://git.kernel.org/stable/c/237aab549676288d9255bb8dcc284738e56eaa31
reply other threads:[~2026-05-13 15:08 UTC|newest]
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