[CVE-2026-72301][MODERATE 7.0] ASoC: SOF: ipc3-control: Fix TOCTOU in bytes_put and bytes_get

[CVE-2026-72301][MODERATE 7.0] ASoC: SOF: ipc3-control: Fix TOCTOU in bytes_put and bytes_get

[AL-KERNEL]

CVE: CVE-2026-72301
Priority: MODERATE 7.0
AL-KERNEL base severity: MODERATE
KPANIC flag: YES
Patch: ASoC: SOF: ipc3-control: Fix TOCTOU in bytes_put and bytes_get
Commit: 8bd715a9d882fe1993bb2aec5eff89fffa946592
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=8bd715a9d882fe1993bb2aec5eff89fffa946592
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-72301
Analysis date: Sun, 16 Aug 2026 02:42:14 -0400
ActionableScore: 8
ActionableScore lower bound: 5
Actionable bucket: Strong Important candidate / Actionable Moderate at minimum
Manual review required: YES

Summary:
A TOCTOU size validation flaw in ASoC SOF IPC3 byte controls can make `bytes_put()` copy using a stale stored size and make `bytes_get()` validate against the wrong buffer bounds, leading to plausible OOB read, constrained OOB write, local DoS, and potential privilege escalation requiring manual review.

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ABOUT THIS REPORT
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The original Linux kernel CVE announcement for CVE-2026-72301 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-72301

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 7.0
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-2026-72301	MODERATE	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:L/UI:N/S:U/C:H/I:H/A:H';CWE-367;*CWE-787;CWE-125;*CWE-20;Other CVSS 'AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:H';BEST CVSS score: '7.8';DESCR 'A TOCTOU size validation flaw in the ASoC SOF IPC3 byte control path can make sof_ipc3_bytes_put use the old stored data size instead of the new user supplied header size. This can copy stale bytes and can also create an out of bounds write when the old size is accepted without accounting for the sof_ipc_ctrl_data header before the flexible data area. sof_ipc3_bytes_get has a related bounds error and can read past the actual available control data area. For the CVSS the PR:L is used because a local process with access to ALSA SOF byte controls can issue the get or put operation, and full administrator privileges are not inherently required in all deployments. The issue is not network reachable. Impact is at least local denial of service and possible information disclosure. In the worst case, the out of bounds write can corrupt kernel heap memory and may allow privilege escalation, so manual review is warranted.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Strong Important candidate / Actionable Moderate at minimum (with actual score 7)	YES	OOB ERRORPATH HARDWARE KPANIC  KPANIC INCREASED_TO_HIGH_BASED_ON_GUESSCVSS DECREASED_TO_MODERATE7_BASED_ON_FALSEPOSCHECKOFKP	NO	NO	checked

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ACTIONABLESCORE ANALYSIS
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ActionableScore=8
ActionableScoreLower=5

## 1. ActionableScore

* Conservative score: 5
* Paranoid score: 8
* Final recommended bucket: **Strong Important candidate / Actionable Moderate at minimum**::

## 2. Signal breakdown

Conservative signals:

* Local unprivileged trigger: +1. A local process with access to ALSA SOF byte controls can reach the get or put path. Full host root is not inherently required in all deployments.
* Constrained kernel buffer overwrite: +1. `sof_ipc3_bytes_put()` used the old stored `data->size` for `memcpy()` instead of the incoming header size. The destination is a kernel control-data buffer, but target selection appears constrained.
* Memory layout invariant restoration: +1. The patch restores consistency between `max_size`, `sizeof(struct sof_ipc_ctrl_data)`, `sizeof(struct sof_abi_hdr)`, and the flexible data area.
* Confidentiality impact plausible: +1. `bytes_get()` had a bounds check that did not account for the `sof_ipc_ctrl_data` header, so an OOB read or stale data exposure is plausible.
* Integrity impact plausible: +1. `bytes_put()` can copy an incorrect amount of user-controlled data into the kernel-side control buffer.

Paranoid additional interpretation:

* Treat constrained overwrite as stronger local heap corruption: +1 net increase. The copy source is user-controlled and the bug affects kernel heap/control data, so a stronger OOB write interpretation is technically defensible.
* Weak LPE concern: +1. No exploit primitive is demonstrated, but local kernel heap corruption can sometimes be developed into privilege escalation.
* Availability impact realistic: +1. OOB read/write in kernel control handling can plausibly cause a crash, even if no panic trace is included.

Call-site confidence: medium. The patch includes the affected get and put functions, but not the full ALSA control call chain or allocation site.

## 3. Reachability analysis

The bug is local, not network reachable. The likely trigger is a local userspace process using ALSA control interfaces on systems with affected ASoC SOF IPC3 support.

Privileges depend on device-node permissions. On many desktop or embedded systems, audio control devices may be reachable by logged-in users, audio group members, or service processes, so PR:L is a reasonable practical assumption. If a product restricts `/dev/snd/control*` to trusted users only, exposure is reduced.

The path is hardware and configuration dependent because it requires SOF IPC3 byte controls. It is not a universal kernel path, but it is reachable through ordinary local sound control interfaces on affected systems.

## 4. Severity interpretation

This is not an ordinary low-risk validation bug. The patch fixes incorrect size selection for `memcpy()` and incorrect bounds accounting around a flexible data area, which supports OOB read and OOB write concerns.

Realistically, the issue is at least Actionable Moderate because local userspace may trigger stale data exposure or kernel memory corruption in a driver control path. The Important-class interpretation is paranoid but defensible because local kernel heap corruption with attacker-supplied data can sometimes become privilege escalation, even though the patch does not demonstrate arbitrary write, controlled reclaim, or a complete LPE primitive.

## 5. One-sentence report phrase

A TOCTOU size validation flaw in ASoC SOF IPC3 byte controls can make `bytes_put()` copy using a stale stored size and make `bytes_get()` validate against the wrong buffer bounds, leading to plausible OOB read, constrained OOB write, local DoS, and potential privilege escalation requiring manual review.

## 6. Manual review recommendation

MANUAL CHECK REQUIRED

Reason: the patch supports a concrete local OOB read and plausible OOB write in kernel memory. Even though exploitability is not proven and the affected path is hardware/configuration dependent, this should not be auto-closed because the bug class can exceed simple DoS.

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

Patch: ASoC: SOF: ipc3-control: Fix TOCTOU in bytes_put and bytes_get
Commit: 8bd715a9d882fe1993bb2aec5eff89fffa946592
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=8bd715a9d882fe1993bb2aec5eff89fffa946592

Commit description:

In sof_ipc3_bytes_put(), the size used for the memcpy is derived from
the old data->size already in the buffer, not the incoming new data's
size field. If the new data has a different size, the copy length is
wrong: it may truncate valid data or copy stale bytes.

Similarly, sof_ipc3_bytes_get() checks data->size against max_size
without accounting for the sizeof(struct sof_ipc_ctrl_data) offset
of the flex array within the allocation.

Fix bytes_put to validate and use the incoming data's sof_abi_hdr.size
from ucontrol before copying. Fix bytes_get to subtract sizeof(*cdata)
from the bounds check to match the actual available space.

Fixes: 544ac88 ("ASoC: SOF: Add bytes_get/put control IPC ops for IPC3")
Cc: stable@vger.kernel.org
Signed-off-by: Peter Ujfalusi <peter.ujfalusi@linux.intel.com>
Reviewed-by: Liam Girdwood <liam.r.girdwood@intel.com>
Reviewed-by: Bard Liao <yung-chuan.liao@linux.intel.com>
Link: https://patch.msgid.link/20260609083458.31193-6-peter.ujfalusi@linux.intel.com
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Changed files:
  sound/soc/sof/ipc3-control.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=8bd715a9d882fe1993bb2aec5eff89fffa946592

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

The original Linux kernel CVE announcement for CVE-2026-72301 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-72301

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:L/PR:L/UI:N/S:U/C:L/I:L/A:H
  The Best / paranoid CVSS vector: AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
  The Best / paranoid CVSS score: 7.8

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: 5
  Paranoid ActionableScore: 8

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: YES
Published priority for this report (same as in Subject): MODERATE 7.0

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).