[CVE-2026-68089][LOW] iio: core: fix uninitialized data in debugfs

[CVE-2026-68089][LOW] iio: core: fix uninitialized data in debugfs

[AL-KERNEL]

CVE: CVE-2026-68089
Priority: LOW
AL-KERNEL base severity: LOW
KPANIC flag: NO
Patch: iio: core: fix uninitialized data in debugfs
Commit: e166a8cfb28a3d0da260dd70cae274eb8c7cec8d
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=e166a8cfb28a3d0da260dd70cae274eb8c7cec8d
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-68089
Analysis date: Mon, 10 Aug 2026 14:29:39 -0400
ActionableScore: 1
ActionableScore lower bound: 0
Actionable bucket: Ordinary Moderate / Low-like
Manual review required: NO

Summary:
An IIO debugfs register write with a non-zero file position could cause the parser to consume uninitialized stack bytes, but typical exploitation requires privileged debugfs access and no direct memory corruption or network exposure is shown.

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

The original Linux kernel CVE announcement for CVE-2026-68089 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-68089

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-2026-68089	LOW	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:L/I:L/A:L';*CWE-457;CWE-908;*CWE-20;Other CVSS 'AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:L/A:L';BEST CVSS score: '4.5';DESCR 'An uninitialized stack buffer use in the IIO debugfs register write path can occur because simple_write_to_buffer writes at *ppos and does not initialize bytes before that offset. If a caller writes with a non-zero file position, later parsing can consume uninitialized bytes from buf instead of only user supplied data. For the CVSS the PR:L is used in the paranoid score only for environments where debugfs access is delegated to a non-root local user or service. In the typical case debugfs register access is administrator controlled, so the realistic base score uses PR:H. The issue is not network reachable and does not show a direct UAF, OOB write, or arbitrary write primitive. Impact is mainly possible incorrect register access or device misconfiguration, with at most limited confidentiality or integrity concern from uninitialized stack data use.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate / Low-like (with actual score 1)  SKIP CVE-2026-68089 UNKNOWN SKIP The Fixes patch not applied yet, so unlikely that actual: 6d5dd486c715908b5a6ed02315a15ff044a91025 YES  NO NO unknown 	MAYBE	SIMPLEFIX DEBUGFS  DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_GUESSCVSS_AND_CIANNH	-	-	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:

* Requires admin/root/debugfs access in typical deployments: -2. The affected path is an IIO debugfs register write interface, which is normally root/admin controlled.
* Rare AND difficult-to-reach subsystem/configuration: -1. The issue requires IIO debugfs exposure and access to this specific debugfs write path.
* Integrity impact plausible: +1. Uninitialized stack bytes may be parsed as part of a debugfs register command, possibly causing unintended device register access or misconfiguration.
* No generic memory corruption bonus. The patch shows uninitialized stack data consumption, not UAF, OOB write, double free, type confusion, refcount abuse, or arbitrary write.
* No reliable kernel crash signal. The commit does not describe Oops, panic, BUG, or a demonstrated crash.
* No confidentiality signal for the conservative score. The uninitialized bytes are consumed internally, and no direct user-visible disclosure path is shown.

Paranoid signals:

* Local delegated trigger: +1. If debugfs access is incorrectly delegated to a non-root local user or service, the trigger may be reachable below full administrator privilege.
* Rare/debugfs exposure still limits practical reachability: -1.
* Limited integrity concern: +1. Parsing uninitialized data in a register access path can plausibly affect device state, but the primitive is weak and highly constrained.

## 3. Reachability analysis

The bug is triggered by writing to an IIO debugfs register file with a non-zero file position. In normal deployments, debugfs is either not mounted, restricted to root, or not exposed to untrusted users, so the conservative interpretation is privileged local access only. Namespace or container impact is low unless a container or service is deliberately given access to the host debugfs IIO files, which would be an unusual and risky configuration. The path is not network reachable and does not involve a common packet-processing, filesystem metadata, page-cache, or high-control unprivileged kernel API.

Call-site confidence: high. The relevant function and changed condition are visible in the provided patch.

## 4. Severity interpretation

This behaves like an ordinary Moderate or Low-like issue, not an Important-class kernel vulnerability. The theoretical concern is that uninitialized stack bytes can influence parsing in a debugfs register write path, but the patch does not show a concrete memory corruption primitive, information leak, privilege escalation path, or reliable crash. Realistic exploitation is constrained by debugfs permissions and by the narrow IIO register-access context.

## 5. One-sentence report phrase

An IIO debugfs register write with a non-zero file position could cause the parser to consume uninitialized stack bytes, but typical exploitation requires privileged debugfs access and no direct memory corruption or network exposure is shown.

## 6. Manual review recommendation

NO MANUAL CHECK NEEDED

This can be auto-closed for practical triage unless the product intentionally exposes IIO debugfs register access to untrusted local users or containers.

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

Patch: iio: core: fix uninitialized data in debugfs
Commit: e166a8cfb28a3d0da260dd70cae274eb8c7cec8d
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=e166a8cfb28a3d0da260dd70cae274eb8c7cec8d

Commit description:

If *ppos is non-zero then simple_write_to_buffer() will not initialize
the start of buf[].  Non zero values for *ppos aren't going to work
anyway.  Test for them at the start of the function and return -EINVAL.

Fixes: 6d5dd48 ("iio: core: make use of simple_write_to_buffer()")
Signed-off-by: Dan Carpenter <error27@gmail.com>
Reviewed-by: Maxwell Doose <m32285159@gmail.com>
Cc: <Stable@vger.kernel.org>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Changed files:
  drivers/iio/industrialio-core.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=e166a8cfb28a3d0da260dd70cae274eb8c7cec8d

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

The original Linux kernel CVE announcement for CVE-2026-68089 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-68089

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:L/A:L
  The Best / paranoid CVSS vector: AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:L
  The Best / paranoid CVSS score: 4.5

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: 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).