[CVE-2026-53123][LOW] md: wake raid456 reshape waiters before suspend [ Upstream

[CVE-2026-53123][LOW] md: wake raid456 reshape waiters before suspend [ Upstream

[AL-KERNEL]

CVE: CVE-2026-53123
Priority: LOW
AL-KERNEL base severity: LOW
KPANIC flag: NO
Patch: md: wake raid456 reshape waiters before suspend [ Upstream
Commit: 8b6a72420821e6da2cab6a69d5233500d2698b93
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=8b6a72420821e6da2cab6a69d5233500d2698b93
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-53123
Analysis date: Wed, 24 Jun 2026 14:30:57 -0400
ActionableScore: 2
ActionableScore lower bound: 1
Actionable bucket: Ordinary Moderate / Low-like
Manual review required: NO

Summary:
A local RAID456 reshape deadlock can occur when md suspend waits for active_io references held by IO sleeping on frozen reshape progress, causing a DoS of md array management operations.

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

The original Linux kernel CVE announcement for CVE-2026-53123 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-53123

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-2026-53123	LOW	CHECK	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-833;CWE-667;**CWE-400;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 local deadlock in md raid456 reshape handling can occur when direct IO across the reshape position sleeps in raid5_make_request while still holding an active_io reference. If reshape is frozen and md suspend is requested through md/suspend_lo or md/suspend_hi, mddev_suspend waits for active_io to drain while the waiting IO cannot make progress because reshape is already stopped. For the CVSS the PR:L is used for the paranoid score because reliable triggering may be possible for a local actor with delegated storage administration or reduced capability root style access to md sysfs controls, while typical systems require full administrative privileges. The issue is not network reachable and affects the storage control plane rather than remote packet processing. Impact is denial of service due to a stuck suspend path and blocked IO or array management operations. NO MANUAL CHECK REQUIRED COULD BE AUTOCLOSED because the patch indicates a deadlock without a memory corruption primitive and the score remains below 5.0.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate / Low-like (with actual score 2)	YES	LOCK DEADLOCK DISK SIMPLEFIX DMAorINTERRUPT LINUS 	YES	NO	checked

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

ActionableScore=2
ActionableScoreLower=1

## 1. ActionableScore

* Conservative score: 1
* Paranoid score: 2
* Final recommended bucket: **Ordinary Moderate / Low-like**

## 2. Signal breakdown

Conservative signals:

* Reliable kernel hang / strong DoS: +1
  The patch fixes a reproducible deadlock where mddev_suspend() waits forever for active_io references while RAID456 reshape waiters cannot make progress.

* Important filesystem/storage path: +1
  The issue affects md RAID456 reshape and suspend handling, which is a storage management path.

* Requires admin/root/CAP-level storage control in typical deployments: -2
  Triggering requires freezing reshape and writing md/suspend_lo or md/suspend_hi, which is normally limited to administrative storage management.

* Special state and sequencing required: -1
  The deadlock requires RAID456 reshape, direct IO crossing the reshape position, reshape freeze/interruption, and suspend operation ordering.

* Availability impact realistic: +1
  The hang can block suspend completion and array management operations, but there is no evidence of memory corruption or data confidentiality/integrity impact.

Paranoid interpretation:

* The score can rise to 2 if delegated storage administration, reduced-capability root, or container/service-level md control is treated as less than full host-root. Even then, the issue remains a DoS-only deadlock.

## 3. Reachability analysis

The bug is locally triggered through md RAID management operations. In normal deployments, the attacker must already have administrative access to manipulate reshape state and md suspend sysfs controls. Namespaces or containers generally do not expose raw md array management to untrusted users, but specialized storage-management environments could delegate enough access to make PR closer to local lower-privileged administration. The path is not network reachable. The affected configuration requires an active RAID456 reshape and a specific suspend/freeze ordering, so realistic exploitation conditions are narrow.

## 4. Severity interpretation

This behaves like an ordinary Moderate or Low-like availability issue rather than an Important-class kernel vulnerability. The patch and commit message show a deadlock caused by waiting IO retaining active_io while reshape is frozen. There is no UAF, OOB access, double free, stale callback, arbitrary write, page-cache corruption, or privilege escalation primitive. Theoretical impact is limited to local DoS through stuck suspend or blocked array management. Realistic exploitation requires privileged storage control and a specific RAID reshape state.

## 5. One-sentence report phrase

A local RAID456 reshape deadlock can occur when md suspend waits for active_io references held by IO sleeping on frozen reshape progress, causing a DoS of md array management operations.

## 6. Manual review recommendation

NO MANUAL CHECK NEEDED

This can be auto-closed for urgent security triage because it is a privileged local storage-control deadlock with no memory corruption, no confidentiality or integrity impact, no network reachability, and a low ActionableScore.

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

Patch: md: wake raid456 reshape waiters before suspend [ Upstream
Commit: 8b6a72420821e6da2cab6a69d5233500d2698b93
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=8b6a72420821e6da2cab6a69d5233500d2698b93

Changed files:
  drivers/md/md.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=8b6a72420821e6da2cab6a69d5233500d2698b93

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

The original Linux kernel CVE announcement for CVE-2026-53123 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-53123

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: 1
  Paranoid ActionableScore: 2

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).