[CVE-2026-80749][MODERATE REGULAR] drm/connector/hdmi: Fix out of bounds memory read

[AL-KERNEL <alkernel@kernelcve.org>]

CVE: CVE-2026-80749
Priority: MODERATE REGULAR
AL-KERNEL base severity: MODERATE
KPANIC flag: NO
Patch: drm/connector/hdmi: Fix out of bounds memory read
Commit: d9f7454c185c0c7f0973e11d62ad6c06862c324c
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=d9f7454c185c0c7f0973e11d62ad6c06862c324c
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80749
Analysis date: Thu, 03 Sep 2026 05:00:05 -0400
ActionableScore: 4
ActionableScore lower bound: 2
Actionable bucket: Borderline, manual review recommended
Manual review required: YES

Summary:
No one-sentence report phrase was found.

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ABOUT THIS REPORT
======================================================================

The original Linux kernel CVE announcement for CVE-2026-80749 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80749

The original announcement does not normally provide a security severity
estimate, CVSS assessment, or enough information to determine whether the
reported kernel bug represents a practically relevant security issue.

This report was generated by AL-KERNEL, an AI-assisted Linux kernel
vulnerability analysis system developed by Alexander Larkin. It combines
an autonomous classifier with LLM-assisted technical analysis and a
separate ActionableScore mechanism.

The purpose of this report is to prioritize Linux kernel CVEs before
manual review, identify cases that require prompt investigation, and
support automatic closure of issues that are unlikely to have meaningful
security impact.

Published priority for this report: MODERATE REGULAR
Manual review required: YES

A detailed explanation of the methodology and priority rules is included
at the end of this message.

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AL-KERNEL CLASSIFICATION RESULT
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CVE-2026-80749	MODERATE	https://www.kernelcve.org/list/?q=CVE-2026-80749 CHECK WITH IMPACT FROM ORIG NN MODERATE	Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:N/A:H';CWE-125;CWE-126;CWE-755;Other CVSS 'AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:N/A:L';BEST CVSS score: '5.3';DESCR 'A local out-of-bounds read in the DRM HDMI connector helper can occur because the audio infoframe helper copies the size of the generic destination buffer instead of the size of the specific source frame. This can read bytes past the end of a smaller HDMI audio infoframe object and may expose adjacent kernel memory only if the extra bytes become observable through the HDMI infoframe path. It can also cause a kernel fault if the read crosses an unmapped page boundary. For the CVSS the PR:L is used because triggering requires local access to DRM KMS or a process that can drive connector state updates. The issue is not network reachable. Impact is mainly local denial of service with possible limited confidentiality impact, and no direct privilege escalation is indicated because the primitive is a read and not a write.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Borderline, manual review recommended (with actual score 3)	YES	WRITE KASAN OOB SIMPLEFIX HARDWARE TEST 	YES	NO	checked

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ACTIONABLESCORE ANALYSIS
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ActionableScore=4
ActionableScoreLower=2

1. ActionableScore
* Conservative score: 2
* Paranoid score: 4
* Final recommended bucket: **Borderline, manual review recommended**::

2. Signal breakdown
* Local unprivileged trigger: +1. A local user or local graphics stack component with access to DRM/KMS connector state may reach the affected helper.
* Confidentiality impact plausible: +1. The bug is an out-of-bounds read from a 28 byte source while copying 60 bytes, so limited adjacent kernel memory exposure is theoretically possible if copied bytes become observable.
* Availability impact realistic: +1 in paranoid scoring only. The commit notes the read could cross a page boundary and cause an access violation, but this is not presented as a reliable real-world crash.
* Broad/default/common subsystem exposure: +1 in paranoid scoring. DRM/HDMI is common on desktop and graphics systems, though not generally relevant to headless servers.
* Hard or unreliable triggering: -1. The author explicitly states real-world impact seems unlikely, and a useful disclosure or crash depends on memory layout and observability.
* Generic memory corruption: +0. This is read-only OOB, not OOB write, UAF, double free, or controlled corruption.
* Privilege escalation plausible: +0. No write primitive, reclaim primitive, callback control, refcount abuse, or object confusion is supported by the patch.

3. Reachability analysis
The likely trigger is local through DRM/KMS connector state updates or a local display stack path, not through network traffic. Access may be available to an interactive local user through normal graphics permissions, but on many systems meaningful modeset control is mediated by DRM master, logind, compositor, or privileged display services. Containers usually do not get DRM device access unless explicitly delegated. The path is common on graphics systems with HDMI support, but the specific failure requires the affected audio infoframe update path and an unfavorable allocation/page layout for a crash or useful data exposure.

4. Severity interpretation
This behaves like a low to borderline Moderate issue rather than an Important-class vulnerability. The theoretical primitive is a limited kernel out-of-bounds read, with possible local DoS if the read crosses into an unmapped page. Realistic exploitation evidence is weak because the patch describes a KUnit/KASAN finding, states real-world impact is unlikely, and does not show a direct user-visible leak, memory corruption, or privilege escalation path. The paranoid score is kept at 4 to avoid auto-closing a kernel OOB read without manual triage, but it does not reach Actionable Moderate under the supplied scoring rules.

5. One-sentence report phrase
A local out-of-bounds read in the DRM HDMI audio infoframe helper can copy beyond a small source frame into the connector infoframe buffer, potentially causing limited information exposure or a page-boundary fault, but no write primitive or privilege escalation path is indicated.

6. Manual review recommendation
MANUAL CHECK RECOMMENDED. This should not be treated as urgent Important-class memory corruption, but a short manual check is justified because it is a kernel OOB read and the actual risk depends on whether extra copied bytes can be observed through the HDMI infoframe path.

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UPSTREAM PATCH SUMMARY
======================================================================

Patch: drm/connector/hdmi: Fix out of bounds memory read
Commit: d9f7454c185c0c7f0973e11d62ad6c06862c324c
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=d9f7454c185c0c7f0973e11d62ad6c06862c324c

Commit description:

A helper function was copying a given audio infoframe into the
connector's copy but using the size of the destination (a generic
target, sized to accept many different data blocks) not the source (a
very specific type of data block). Thus, it was copying 60 bytes of
data from a 28 byte allocation.

Fix that by using the source size instead, together with a build bug
on the source size actually being smaller than the destination.

I hit this running KUnit tests under KASAN (while debugging something
else entirely). In the real world, it seems unlikely to cause an
actual problem. It is a read not a write so it can't corrupt any
memory. However, it could potentially fall off the end of a page and
cause an accvio bug.

Fixes: f378b77 ("drm/connector: hdmi: Add Infoframes generation")
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Cc: Maxime Ripard <mripard@kernel.org>
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Thomas Zimmermann <tzimmermann@suse.de>
Cc: David Airlie <airlied@gmail.com>
Cc: Simona Vetter <simona@ffwll.ch>
Cc: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
Cc: Daniel Stone <daniel@fooishbar.org>
Cc: Nicolas Frattaroli <nicolas.frattaroli@collabora.com>
Cc: Jani Nikula <jani.nikula@intel.com>
Cc: José Expósito <jose.exposito89@gmail.com>
Cc: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Cc: dri-devel@lists.freedesktop.org
Cc: stable@vger.kernel.org # v6.11+
Signed-off-by: John Harrison <John.Harrison@Igalia.com>
Link: https://patch.msgid.link/20260723220652.533345-1-John.Harrison@Igalia.com
Signed-off-by: Maxime Ripard <mripard@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Changed files:
  drivers/gpu/drm/display/drm_hdmi_state_helper.c

Diff excerpt:

Not included in this email. See the upstream URL for the full patch.

Full patch:
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=d9f7454c185c0c7f0973e11d62ad6c06862c324c

======================================================================
DETAILED REPORT METHODOLOGY
======================================================================

The original Linux kernel CVE announcement for CVE-2026-80749 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80749

The original CVE announcement normally does not include a security-level
estimate. In particular, it may not contain a CVSS assessment, an impact
level, or enough information to determine whether the reported bug is a
practically relevant security issue. One purpose of this parallel CVE list
is to provide that missing technical and prioritization information.

The original goal of the AL-KERNEL project was to prioritize Linux kernel
CVE analysis automatically before manual review. The system can also help
identify non-security issues that may be suitable for automatic closure.

This report was generated by AL-KERNEL, an AI-assisted Linux kernel
vulnerability analysis system developed by Alexander Larkin.

The first analysis stage combines an autonomous classifier with additional
LLM-based analysis. The autonomous classifier runs locally on a CPU and is
based on a backpropagation neural network. Together, these mechanisms
produce a technical vulnerability description, identify likely weakness
types, estimate CVSS severity, and provide input for ActionableScore.

Two CVSS estimates are retained because incomplete kernel vulnerability
information often permits more than one defensible interpretation:

  Conservative CVSS vector: AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:N/A:L
  The Best / paranoid CVSS vector: AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:N/A:H
  The Best / paranoid CVSS score: 5.3

The conservative vector represents a lower-impact interpretation.
The Best/paranoid vector intentionally represents a plausible upper-bound
interpretation and should not automatically be treated as demonstrated
real-world impact.

CVSS may also need to be adjusted for a particular Linux deployment,
because actual reachability, privileges, enabled kernel configuration,
hardware, namespaces, exposed device nodes, and other environmental
conditions can differ significantly between systems.

A separate ActionableScore mechanism evaluates practical remediation
urgency. Its analysis may include reachability, attack prerequisites,
subsystem exposure, memory-corruption characteristics, denial-of-service
reliability, and possible confidentiality, integrity, or
privilege-escalation impact.

  Conservative ActionableScore: 2
  Paranoid ActionableScore: 4

The final base severity is taken directly from the second tab-separated
field of the AL-KERNEL classification result. ActionableScore does not
replace or independently override that final AL-KERNEL decision, and
if ActionableScore adjusted impact level of ALKERNEL, then you would see
self-readable flags above like INCREASED_TO_HIGH_BASED_ON_ACTIONABLESCOREHIGHEREQTHAN7.

For an AL-KERNEL result of MODERATE, this report uses the following
additional presentation split:

  ActionableScore below 5   -> MODERATE REGULAR
  ActionableScore 5 or more -> MODERATE 7.0

The distinction between MODERATE REGULAR and MODERATE 7.0 makes it
possible to identify Moderate issues that should receive manual analysis
and fixes before lower-priority MODERATE REGULAR issues. In many cases,
MODERATE REGULAR fixes may wait for a later rebase or routine update.

There is one override in which MODERATE REGULAR becomes MODERATE 7.0
even when the ActionableScore is below 5. When the AL-KERNEL result
contains the KPANIC flag, a MODERATE result is always presented as
MODERATE 7.0. The KPANIC flag selected with few regexps without
usage of AI at all, so it helps to detect cases when Kernel Crash happens
and similar (to filter False-Negative results from the LLM usage).

KPANIC indicates that a reliable kernel crash, kernel panic, or similarly
serious kernel availability impact was identified by the classification
workflow.

AL-KERNEL base severity for this report: MODERATE
KPANIC detected for this report: NO
Published priority for this report (same as in Subject): MODERATE REGULAR

These results are intended to support engineering triage. They are
machine-generated estimates, and cases marked for manual review should
be validated by a human security engineer before final disposition.
For more info read docs linked from here: https://kernelcve.org/
(and you can submit you own patch there to generate such a report
for non-existant CVE-id yet).

Note that in many cases this AI tool selects higher severity, than
real is (means you can expect Importants instead of Moderate 7.0 or
Moderates 7.0 instead of regular Moderates). If you see such cases,
please use reply email interface to add additional manual analyses
info to this particular CVE.
And please, please, let me know when you see Lows instead of Importants
or Important instead of Low (because particular for such cases I
need to tune this AI tool to make it better for this one and next similar).
My contact email for such notifications is alexanjelausa@gmail.com (and both
send reply to CVE record itself too and see "reply" button below for howto reply).