[CVE-2022-49733][MODERATE REGULAR] ALSA: pcm: oss: Fix race at SNDCTL_DSP_SYNC [ Upstream

[CVE-2022-49733][MODERATE REGULAR] ALSA: pcm: oss: Fix race at SNDCTL_DSP_SYNC [ Upstream

[AL-KERNEL]

CVE: CVE-2022-49733
Priority: MODERATE REGULAR
AL-KERNEL base severity: MODERATE
KPANIC flag: NO
Patch: ALSA: pcm: oss: Fix race at SNDCTL_DSP_SYNC [ Upstream
Commit: 4051324a6dafd7053c74c475e80b3ba10ae672b0
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=4051324a6dafd7053c74c475e80b3ba10ae672b0
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2022-49733
Analysis date: Thu, 24 Sep 2026 15:53:07 -0400
ActionableScore: 1
ActionableScore lower bound: unknown
Actionable bucket: Ordinary Moderate
Manual review required: NO

Summary:
No one-sentence report phrase was found.

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

The original Linux kernel CVE announcement for CVE-2022-49733 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2022-49733

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: NO

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

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

CVE-2022-49733	MODERATE	https://www.kernelcve.org/list/?q=CVE-2022-49733 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:N/I:N/A:H';CWE-362;**CWE-476;CWE-667;BEST CVSS score: '4.7';DESCR 'A race in ALSA PCM OSS can occur when SNDCTL_DSP_SYNC prepares a stream before taking params_lock while another thread concurrently reconfigures the same stream. The first thread can then continue with inconsistent OSS runtime and buffer state and reach a NULL pointer dereference, causing a kernel Oops or panic. For the CVSS the PR:L value is used because an attacker needs local code execution and permission to access the affected OSS PCM device, but does not normally need an administrative capability. AC:H is used because successful triggering depends on winning a concurrent timing window between stream preparation and reconfiguration. The issue is not network reachable. Impact is local denial of service through a kernel crash. The analyzed code supports a NULL dereference but does not establish a UAF, OOB write, arbitrary write, information leak, or credible privilege escalation primitive.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate (with actual score 1) 	MAYBE	READ NULLPTR SIMPLEFIX RACE HARDWARE LINUS CVEOUTDATED 	-	-	checked

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

ActionableScore=1
PrimitiveClass=CLASS_C
RealUAF=NO
HostAdminRequired=NO
NamespaceScopedPrivilege=NO
ImportantCandidate=NO
ManualReview=RECOMMENDED
AutoDowngradeAllowed=YES

1. ActionableScore

* Raw conservative score: 1
* Conservative score: 1
* Raw paranoid score: 1
* Paranoid score: 1
* No floor or cap applied.
* Final recommended bucket: **Ordinary Moderate**::

2. Signal breakdown

Positive signals:

* +1 Local unprivileged trigger. A local process with permission to access the OSS PCM device can issue SNDCTL_DSP_SYNC and concurrently reconfigure the stream. Host-admin-equivalent privilege is not required.
* +1 Reliable kernel crash or strong DoS. The commit reports a fuzzer-observed NULL dereference of the OSS buffer, supporting a kernel Oops or panic.

Negative signals:

* -1 Hard timing requirement. The commit explicitly describes a small race window between snd_pcm_oss_make_ready() and acquisition of params_lock.

Non-awarded signals:

* No UAF or post-lifetime object use is established.
* No OOB access, arbitrary write, controlled reclaim, disclosure, or privilege-escalation primitive is demonstrated.
* No structured stale-object leverage or repeated lifetime/refcount mutation exists.
* Remote reachability is not established.
* No additional Availability point is awarded because it would duplicate the same NULL-dereference crash.
* No legacy-mode penalty is applied merely because this is the OSS compatibility interface.

3. Reachability analysis

The attacker is a local process that can open the affected OSS PCM device. Device-node permissions may restrict access to an active desktop user, audio group, service, or another delegated account, but this remains below host-admin privilege under normal ALSA device-access semantics.

The attacker can use two threads sharing the stream to race SNDCTL_DSP_SYNC against stream reconfiguration. The commit calls the window small, so the timing penalty is supported, although repeated attempts may improve reproducibility.

The operation is based on device-file permissions rather than a namespace-scoped capability. No network trigger exists. CONFIG_SND_PCM_OSS or equivalent OSS PCM support and an accessible PCM device are prerequisites, but special or rare hardware is not established.

4. Primitive and severity interpretation

The exact primitive is inconsistent OSS runtime and buffer state followed by a NULL pointer dereference. This is Class C crash behavior, not a lifetime violation or independently useful memory-corruption primitive.

There is no first operation that ends an object lifetime, no dangling reference, and no second release or refcount mutation. The demonstrated consequence is local kernel DoS. Privilege escalation, confidentiality loss, and integrity compromise remain unsupported.

ImportantCandidate is NO because useful exploitation leverage beyond the crash is not established. AutoDowngradeAllowed is YES because the issue is a constrained NULL-dereference race without unresolved ownership, lifetime, authorization, or controlled-corruption semantics.

Likely operational severity is ordinary Moderate or lower, depending on whether untrusted local users can access the OSS PCM device.

5. One-sentence report phrase

A local user with access to an OSS PCM device can race SNDCTL_DSP_SYNC against stream reconfiguration, causing inconsistent buffer state and a NULL pointer dereference that may crash the kernel.

6. Manual review recommendation

MANUAL CHECK RECOMMENDED

The technical evidence supports crash-only Class C behavior, but a brief review should confirm product-specific OSS PCM enablement, device permissions, and whether kernel Oops handling makes the failure host-fatal.

7. Call-site confidence

Call-site confidence: medium

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

Patch: ALSA: pcm: oss: Fix race at SNDCTL_DSP_SYNC [ Upstream
Commit: 4051324a6dafd7053c74c475e80b3ba10ae672b0
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=4051324a6dafd7053c74c475e80b3ba10ae672b0

Changed files:
  sound/core/oss/pcm_oss.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=4051324a6dafd7053c74c475e80b3ba10ae672b0

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

The original Linux kernel CVE announcement for CVE-2022-49733 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2022-49733

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: Not available
  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: unknown
  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: 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).