[CVE-2026-89944][LOW] ASoC: hdac_hda: Fix hlink refcount leak on component registration failure

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

CVE: CVE-2026-89944
Priority: LOW
AL-KERNEL base severity: LOW
KPANIC flag: NO
Patch: ASoC: hdac_hda: Fix hlink refcount leak on component registration failure
Commit: 7eef9ae3b4ef782557526dd8ba0c206f028d8c2f
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=7eef9ae3b4ef782557526dd8ba0c206f028d8c2f
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-89944
Analysis date: Wed, 16 Sep 2026 10:19:45 -0400
ActionableScore: 0
ActionableScore lower bound: unknown
Actionable bucket: Ordinary Moderate
Manual review required: NO

Summary:
No one-sentence report phrase was found.

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

The original Linux kernel CVE announcement for CVE-2026-89944 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-89944

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: LOW
Manual review required: NO

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

======================================================================
AL-KERNEL CLASSIFICATION RESULT
======================================================================

CVE-2026-89944	LOW	https://www.kernelcve.org/list/?q=CVE-2026-89944 CHECK WITH IMPACT FROM ORIG NN LOW	Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:L';*CWE-772;CWE-404;**CWE-400;Other CVSS 'AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '2.3';DESCR 'ASoC hdac_hda can leak an HDA link reference when hdac_hda_dev_probe gets a link with snd_hdac_ext_bus_link_get() and component registration fails before the matching put operation is reached. This is a local resource lifetime bug in an audio codec probe error path rather than a memory corruption primitive. For the CVSS the PR:H is used because reliable triggering normally requires administrative control over driver probing, device binding, module reload, or hardware related failure conditions. The issue is not network reachable and is not triggered by packet traffic. Impact is limited denial of service or resource leakage, with no supported path to information disclosure or privilege escalation.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate (with actual score 0)	YES	SIMPLEFIX LEAK HARDWARE 	NO	NO	checked

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ACTIONABLESCORE ANALYSIS
======================================================================

ActionableScore=0
PrimitiveClass=NONE
RealUAF=NO
HostAdminRequired=YES
NamespaceScopedPrivilege=NO
ImportantCandidate=NO
ManualReview=NO
AutoDowngradeAllowed=YES

1. ActionableScore

* Raw conservative score: 0
* Conservative score: 0
* Raw paranoid score: 0
* Paranoid score: 0
* No floor or cap changed the score.
* Final recommended bucket: **Ordinary Moderate**::

2. Signal breakdown

Positive signals:

* +1 Concrete persistent kernel resource/reference leak. The patch directly shows snd_hdac_ext_bus_link_get() taking an HDA link reference before component registration and the old error path returning without the matching snd_hdac_ext_bus_link_put().
* +0 Reliable kernel crash / strong DoS not awarded. The supplied evidence establishes a leaked hlink reference, not an immediate host-wide crash or panic.
* +0 Confidentiality and integrity not awarded. No disclosure, overwrite, UAF, double release, arbitrary write, or authorization bypass is established.
* +0 Concrete repeated release/refcount not awarded. This is a missing put, not a second put on the same potentially dangling reference.
* +0 Real UAF not awarded. The object is retained too long rather than used after being freed.
* +0 Structured stale-object leverage not awarded. There is no stale object consumption after lifetime end.
* +0 Remote reachability not awarded. This is an audio codec probe path, not a network data path.

Negative signals:

* -2 Host-admin-equivalent triggering requirement. Reliable attacker-driven triggering would normally require administrative control over driver probing, device binding, module loading, or hardware/probe failure conditions.

Arithmetic:

* Conservative: +1 -2 = -1, clamped to 0.
* Paranoid: +1 -2 = -1, clamped to 0.
* No paranoid escalation is justified because the established primitive remains a reference leak only.

3. Reachability analysis

The vulnerable path is hdac_hda_dev_probe() in the ASoC HDA codec driver. A normal unprivileged local user is not shown to be able to force this probe path or reliably cause component registration failure. The practical attacker model is host administrator or host-admin-equivalent control over module loading, driver binding, device management, or fault conditions during probe.

No namespace-scoped capability path is established. This is not a network-reachable issue. No prior attacker-obtainable unprivileged API is shown. The issue depends on the relevant HDA/ASoC driver and device path, but the hardware-specific nature is not used as an additional penalty beyond the host-admin-trigger requirement.

Race repeatability is not relevant. The bug is an ordered error-path resource leak, not a timing race.

4. Primitive and severity interpretation

The exact primitive is a missing release of a lifetime reference acquired by snd_hdac_ext_bus_link_get(). The reference is leaked if component registration fails before snd_hdac_ext_bus_link_put() is reached.

This is not an active-object UAF, not fixed stale storage, and not a cleanup stale dereference. There is no concrete repeated release/refcount operation. The first operation acquires a reference. The missing second operation fails to drop it. No later second lifetime mutation through a dangling reference is established.

PrimitiveClass=NONE because the patch establishes resource/reference leakage but not memory corruption, stale post-lifetime use, ownership violation, authorization bypass, or semantic reinterpretation.

Demonstrated consequence is limited resource/reference leakage and possible device or power-management cleanup inconsistency. Speculative consequence is limited local DoS after repeated administrative triggering, but there is no evidence of host-wide exhaustion, information disclosure, integrity impact, or privilege escalation.

ImportantCandidate=NO because no Important-grade primitive is present. AutoDowngradeAllowed=YES because this is a constrained reference leak with host-admin-equivalent triggering and no unresolved corruption or boundary primitive.

Likely operational severity is Low / ordinary Moderate-like.

5. One-sentence report phrase

ASoC hdac_hda can leak an HDA link reference when component registration fails during probe, but triggering normally requires host administrative control and the demonstrated impact is limited resource leakage rather than memory corruption or privilege escalation.

6. Manual review recommendation

NO MANUAL CHECK NEEDED

The issue is a straightforward missing put on an error path with no UAF, double release, security-boundary bypass, network reachability, or plausible Important-grade exploitation primitive.

7. Call-site confidence

Call-site confidence: high

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

Patch: ASoC: hdac_hda: Fix hlink refcount leak on component registration failure
Commit: 7eef9ae3b4ef782557526dd8ba0c206f028d8c2f
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=7eef9ae3b4ef782557526dd8ba0c206f028d8c2f

Commit description:

hdac_hda_dev_probe() gets the HDA link with snd_hdac_ext_bus_link_get()
before registering the ASoC component. If component registration fails,
the function returns without dropping the link reference.

Always call snd_hdac_ext_bus_link_put() after the registration attempt so
the reference taken during probe is balanced on both success and failure.

Fixes: 6bae5ea ("ASoC: hdac_hda: add asoc extension for legacy HDA codec drivers")
Cc: stable@vger.kernel.org
Signed-off-by: Haoxiang Li <haoxiang_li2024@163.com>
Link: https://patch.msgid.link/20260622145645.1184986-1-haoxiang_li2024@163.com
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Changed files:
  sound/soc/codecs/hdac_hda.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=7eef9ae3b4ef782557526dd8ba0c206f028d8c2f

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

The original Linux kernel CVE announcement for CVE-2026-89944 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-89944

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:H/UI:N/S:U/C:N/I:N/A:L
  The Best / paranoid CVSS vector: AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:L
  The Best / paranoid CVSS score: 2.3

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: unknown
  Paranoid ActionableScore: 0

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: LOW
KPANIC detected for this report: NO
Published priority for this report (same as in Subject): LOW

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).