[CVE-2026-64482][LOW] ALSA: gus: check snd_ctl_new1() return value

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

CVE: CVE-2026-64482
Priority: LOW
AL-KERNEL base severity: LOW
KPANIC flag: YES
Patch: ALSA: gus: check snd_ctl_new1() return value
Commit: 97f6bdf5d5ded2e37f358cacb5a95f1393356604
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=97f6bdf5d5ded2e37f358cacb5a95f1393356604
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-64482
Analysis date: Sat, 25 Jul 2026 08:56:01 -0400
ActionableScore: 1
ActionableScore lower bound: 0
Actionable bucket: Ordinary Moderate / Low-like
Manual review required: NO

Summary:
An unchecked `snd_ctl_new1()` allocation failure in the ALSA GUS driver can cause a NULL pointer dereference during PCM control setup, but triggering is local, unreliable, and normally tied to privileged legacy driver initialization.

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ABOUT THIS REPORT
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The original Linux kernel CVE announcement for CVE-2026-64482 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-64482

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
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CVE-2026-64482	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-755;Other CVSS 'AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '4.7';DESCR 'A NULL pointer dereference can occur in the ALSA gus driver because snd_gf1_pcm_new calls snd_ctl_new1 and then dereferences kctl id index without checking whether the allocation returned NULL. The failure path depends on memory allocation failure during PCM control setup for the gus driver, so reliable triggering is difficult and normally tied to driver or device initialization. For the CVSS the PR:L is used for the paranoid view because a local user could theoretically contribute through memory pressure while a privileged driver setup path is running, although the realistic base case is PR:H. The issue is not network reachable and does not provide an obvious write primitive, UAF primitive, or information leak. Impact is denial of service via kernel crash only.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate / Low-like (with actual score 1)  SKIP CVE-2026-64482 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
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ActionableScore=1
ActionableScoreLower=0

## 1. ActionableScore

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

## 2. Signal breakdown

* Reliable kernel crash / strong DoS: +1. If `snd_ctl_new1()` returns NULL, the next dereference of `kctl->id.index` can cause a NULL pointer dereference.
* Local unprivileged trigger, paranoid only: +1. A local user might theoretically contribute via memory pressure while a privileged driver setup path is running.
* Hard or unreliable condition: -1. The bug depends on allocation failure in a narrow initialization path, not a normal attacker-controlled operation.
* Requires admin/root/CAP_* in typical deployments: -2 conservative. Reliable triggering is normally tied to loading or initializing the legacy ALSA GUS driver.
* Legacy / non-default execution mode: -1. The affected path is for an old ISA GUS sound driver and is not a common default deployment path.
* No generic memory corruption bonus. This is a NULL dereference, not UAF, OOB write, double free, type confusion, or refcount corruption.
* No LPE bonus. The patch does not show reclaim, object replacement, writable stale object access, callback control, or arbitrary write.
* Call-site confidence: high. The failing allocation and immediate dereference are visible in the provided diff.

## 3. Reachability analysis

The realistic trigger is local and privileged, involving initialization of the ALSA GUS PCM/control path. In normal deployments, loading or probing this legacy hardware driver is administrator controlled. A paranoid interpretation allows a local unprivileged user to influence memory pressure, but they still do not directly control the driver initialization path. Namespaces or containers do not materially improve reachability unless the host delegates unusual device or module management privileges. The path is not network reachable and is not default-relevant on most modern systems.

## 4. Severity interpretation

This behaves like an ordinary Moderate or Low-like kernel robustness issue. The theoretical impact is a kernel crash from NULL pointer dereference under allocation failure. Realistic exploitation evidence for privilege escalation is absent, and the bug does not expose a meaningful memory corruption primitive. It should not be treated as an Important-class vulnerability.

## 5. One-sentence report phrase

An unchecked `snd_ctl_new1()` allocation failure in the ALSA GUS driver can cause a NULL pointer dereference during PCM control setup, but triggering is local, unreliable, and normally tied to privileged legacy driver initialization.

## 6. Manual review recommendation

NO MANUAL CHECK NEEDED

This can be auto-closed for urgent triage purposes because it is a legacy local allocation-failure NULL dereference with no network exposure, no UAF or write primitive, and no plausible privilege escalation path shown by the patch.

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

Patch: ALSA: gus: check snd_ctl_new1() return value
Commit: 97f6bdf5d5ded2e37f358cacb5a95f1393356604
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=97f6bdf5d5ded2e37f358cacb5a95f1393356604

Commit description:

snd_ctl_new1() can return NULL when memory allocation fails.
snd_gf1_pcm_volume_control() does not check the return value before
dereferencing kctl->id.index, which can lead to a NULL pointer
dereference.

Add a NULL check after snd_ctl_new1() and return -ENOMEM if it fails.

Assisted-by: Opencode:DeepSeek-V4-Flash
Cc: stable@vger.kernel.org
Fixes: c5ae57b ("ALSA: gus: Fix kctl->id initialization")
Signed-off-by: Zhao Dongdong <zhaodongdong@kylinos.cn>
Link: https://patch.msgid.link/tencent_F644A3DCAD32945D62DB2FEEBE8A996F6809@qq.com
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Changed files:
  sound/isa/gus/gus_pcm.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=97f6bdf5d5ded2e37f358cacb5a95f1393356604

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

The original Linux kernel CVE announcement for CVE-2026-64482 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-64482

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).