[CVE-2026-64489][LOW] ALSA: ymfpci: check snd_ctl_new1() return value

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

CVE: CVE-2026-64489
Priority: LOW
AL-KERNEL base severity: LOW
KPANIC flag: YES
Patch: ALSA: ymfpci: check snd_ctl_new1() return value
Commit: d7c71dfd4b80f0eacac2c157a8a3a4c6e8b2e0d1
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=d7c71dfd4b80f0eacac2c157a8a3a4c6e8b2e0d1
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-64489
Analysis date: Sat, 25 Jul 2026 07:19:38 -0400
ActionableScore: 1
ActionableScore lower bound: 0
Actionable bucket: Ordinary Moderate / Low-like
Manual review required: NO

Summary:
ALSA ymfpci may dereference a NULL mixer control pointer if snd_ctl_new1() fails during SPDIF control creation, causing a local crash-only DoS under memory pressure and rare hardware or driver initialization conditions.

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

The original Linux kernel CVE announcement for CVE-2026-64489 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-64489

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.

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

CVE-2026-64489	LOW	CHECK WITH IMPACT FROM ORIG NN NONE	Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H';**CWE-476;CWE-252;CWE-703;Other CVSS 'AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '4.7';DESCR 'ALSA ymfpci can dereference a NULL control pointer because snd_ctl_new1() may fail under memory pressure and the returned kctl pointer was used before being checked. The fault occurs during creation of SPDIF mixer controls for the ymfpci PCI audio driver and can lead to a kernel oops or crash. For the CVSS the PR:L is used in the paranoid score because a local unprivileged process may contribute to memory pressure while driver initialization is triggered by hotplug, boot, or an administrator action. The issue is not network reachable and requires local system context plus the affected hardware or driver path. Impact is denial of service only. For the paranoid score, the highest still-defensible interpretation remains a local availability issue because this is a NULL dereference after allocation failure, not a UAF, OOB access, or arbitrary write primitive.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate / Low-like (with actual score 1)  SKIP CVE-2026-64489 UNKNOWN SKIP No affected files built, so skip this CVE NO  - - unknown 	MAYBE	NULLPTR NOMEMCHK SIMPLEFIX HARDWARE LINUS KPANIC 	-	-	checked

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

ActionableScore=1
ActionableScoreLower=0

## 1. ActionableScore

* Conservative score: 0
* Paranoid score: 1
* Final recommended bucket: **Ordinary Moderate / Low-like**::

## 2. Signal breakdown

Conservative signals:

* Reliable kernel crash / strong DoS: +1. A NULL pointer dereference is possible if `snd_ctl_new1()` fails and `kctl->id.device` is dereferenced.
* Requires admin/root/CAP_* in typical deployments: -2. Reliable triggering normally requires driver initialization, device reprobe, module handling, or hardware setup control.
* Physical-only or rare hardware-only condition: -2. The affected path is tied to the legacy Yamaha YMFPCI ALSA PCI driver and SPDIF mixer control creation.
* Hard or unreliable condition: -1. The crash depends on memory allocation failure at a narrow initialization point.

Paranoid adjustment:

* Local unprivileged trigger: +1. A local user may contribute to memory pressure while boot, hotplug, or an administrator triggers driver initialization, but this is indirect and unreliable.

No additional signals:

* No generic memory corruption. This is NULL dereference, not UAF, double free, OOB write, type confusion, or arbitrary write.
* No privilege escalation plausible signal. No reclaim, object replacement, callback control, write primitive, or refcount abuse is shown.
* No confidentiality or integrity impact. The visible primitive is crash-only.
* No high-control device API bonus. ALSA object creation alone does not show attacker control over memory layout or lifetime.

## 3. Reachability analysis

The vulnerable path is reached during ALSA ymfpci mixer initialization when SPDIF controls are created. In typical deployments, an attacker needs administrative control over driver loading, reprobe, or device initialization to reliably hit the path. A weaker paranoid scenario exists where an unprivileged local user creates memory pressure while the driver is being initialized by boot, hotplug, or an administrator, but that does not provide a reliable direct trigger.

Namespaces and containers do not materially improve reachability unless the container can influence host driver initialization or host memory pressure. The path is not network reachable. The affected hardware and driver are uncommon, so exposure is limited.

Call-site confidence: high. The patch shows the allocation return value and immediate dereference in the same function.

## 4. Severity interpretation

This behaves like a low-end ordinary Moderate or Low-like kernel DoS issue. The theoretical impact is a kernel oops or crash under allocation failure. Realistic exploitation is weak because the bug requires a rare hardware driver path and an allocation failure during initialization. There is no evidence of a practical memory corruption primitive or privilege escalation path.

## 5. One-sentence report phrase

ALSA ymfpci may dereference a NULL mixer control pointer if snd_ctl_new1() fails during SPDIF control creation, causing a local crash-only DoS under memory pressure and rare hardware or driver initialization conditions.

## 6. Manual review recommendation

NO MANUAL CHECK NEEDED.

This can be auto-closed for most environments because it is a NULL dereference on allocation failure in a rare legacy PCI audio driver path, with no evidence of UAF, OOB write, privilege escalation, information disclosure, or network reachability.

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

Patch: ALSA: ymfpci: check snd_ctl_new1() return value
Commit: d7c71dfd4b80f0eacac2c157a8a3a4c6e8b2e0d1
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=d7c71dfd4b80f0eacac2c157a8a3a4c6e8b2e0d1

Commit description:

snd_ctl_new1() can return NULL when memory allocation fails.
snd_ymfpci_create_spdif_controls() does not check the return value
before dereferencing kctl->id.device, which can lead to a NULL pointer
dereference.

Add NULL checks after snd_ctl_new1() calls and return -ENOMEM if any
fails.

Assisted-by: Opencode:DeepSeek-V4-Flash
Cc: stable@vger.kernel.org
Fixes: c9b83ae ("ALSA: ymfpci: Fix kctl->id initialization")
Signed-off-by: Zhao Dongdong <zhaodongdong@kylinos.cn>
Link: https://patch.msgid.link/tencent_4745C5DC2333325C0EDAB1EFC88A136E6809@qq.com
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Changed files:
  sound/pci/ymfpci/ymfpci_main.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=d7c71dfd4b80f0eacac2c157a8a3a4c6e8b2e0d1

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

The original Linux kernel CVE announcement for CVE-2026-64489 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-64489

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:H
  The Best / paranoid CVSS vector: AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H
  The Best / paranoid CVSS score: 4.7

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: 0
  Paranoid ActionableScore: 1

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: YES
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).