[CVE-2026-74555][LOW] scsi: libsas: Fix HA resume deadlock and hisi_sas disk-wake race [ Upstream

[CVE-2026-74555][LOW] scsi: libsas: Fix HA resume deadlock and hisi_sas disk-wake race [ Upstream

[AL-KERNEL]

CVE: CVE-2026-74555
Priority: LOW
AL-KERNEL base severity: LOW
KPANIC flag: NO
Patch: scsi: libsas: Fix HA resume deadlock and hisi_sas disk-wake race [ Upstream
Commit: e50a6523a603594a6d92cdecfe11997d639410a3
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=e50a6523a603594a6d92cdecfe11997d639410a3
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-74555
Analysis date: Sat, 15 Aug 2026 12:06:59 -0400
ActionableScore: 2
ActionableScore lower bound: 1
Actionable bucket: Ordinary Moderate / Low-like
Manual review required: NO

Summary:
A libsas resume ordering race can deadlock HA resume or let hisi_sas resume before PHY and discovery work completes, causing failed I/O and disabled disks on affected SAS systems.

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

The original Linux kernel CVE announcement for CVE-2026-74555 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-74555

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.

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

CVE-2026-74555	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:N/I:N/A:H';*CWE-833;CWE-362;CWE-667;Other CVSS 'AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '4.7';DESCR 'libsas resume handling could deadlock the HA event workqueue or let hisi_sas finish resume before pending PHY and discovery work completed. This can cause I/O to reach a suspended controller while disks are still waking up, resulting in failed I/O and disabled disks. For the CVSS the PR:L is used in the paranoid score because some systems allow a local user or service to trigger suspend resume or runtime power management without full administrator control. The issue is not network reachable and requires a local power management or hardware state transition on affected SAS setups. Impact is denial of service to storage availability, with no supported evidence of information disclosure, memory corruption, or privilege escalation.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate / Low-like (with actual score 2)  SKIP CVE-2026-74555 UNKNOWN SKIP The Fixes patch not applied yet, so unlikely that actual: fbefe22811c3140a686e407e114789ebf328a9a2 YES  NO NO unknown 	MAYBE	DEADLOCK INIT RACE HARDWARE  DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_GUESSCVSS_AND_CIANNH	-	-	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

Triggered signals:

* Reliable kernel crash / strong DoS: +1
  The issue can deadlock HA resume or cause disks to be disabled after failed I/O during resume/autosuspend ordering.

* Important filesystem/storage path: +1
  The affected path is SCSI/SAS resume handling and can affect storage availability.

* Availability impact realistic: +1 in paranoid only
  Disk disablement can persist beyond a single failed operation and may require recovery action, but this is hardware and power-management dependent.

Subtracted signals:

* Hard or unreliable race / special timing required: -1
  The failure depends on suspend/resume ordering, PHY timeout handling, pending discovery work, and autosuspend timing.

* Requires admin/root/CAP or privileged power management in typical deployments: -2 conservative
  Reliable triggering usually requires system suspend/resume, runtime PM control, device removal, or hardware state transitions.

* Rare AND difficult-to-reach subsystem/configuration: -1
  This is specific to libsas users and especially hisi_sas resume behavior, not a broad default kernel path.

Not applied:

* No remote reachable signal.
* No local high-control API signal.
* No memory corruption signal.
* No LPE signal.
* No confidentiality or integrity signal.

Call-site confidence: high. The relevant resume call path and ordering changes are visible in the patch.

## 3. Reachability analysis

The bug is triggered through SAS host adapter resume handling, especially on hisi_sas systems. In typical server deployments, suspend/resume and runtime PM transitions are controlled by root or privileged system services, so conservative reachability is privileged local only. A paranoid interpretation allows PR:L-like practical reachability if a local user or service can cause suspend/resume or influence runtime power management policy, but this is deployment dependent.

Namespaces and containers do not materially lower reachability in normal configurations because the affected path is physical host storage power management, not a namespaced interface. The path is not network reachable. Exploitation requires affected SAS hardware, suspend/resume timing, and disk wakeup or PHY timeout conditions.

## 4. Severity interpretation

This behaves like an ordinary Moderate or Low-like storage availability issue, not an Important-class kernel vulnerability. The patch fixes a deadlock/race in resume sequencing and prevents storage I/O failures or disabled disks, but it does not show UAF, OOB access, stale pointer reuse, arbitrary write, type confusion, refcount abuse, information disclosure, or privilege escalation.

The theoretical impact is storage DoS. Realistic exploitation evidence supports availability loss under specific hardware and power-management conditions, not memory corruption or privilege escalation.

## 5. One-sentence report phrase

A libsas resume ordering race can deadlock HA resume or let hisi_sas resume before PHY and discovery work completes, causing failed I/O and disabled disks on affected SAS systems.

## 6. Manual review recommendation

NO MANUAL CHECK NEEDED

This can be handled as a non-urgent storage availability issue because the trigger is local or hardware and power-management dependent, the affected subsystem is relatively narrow, and the patch does not support memory corruption, privilege escalation, confidentiality impact, or network reachability.

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

Patch: scsi: libsas: Fix HA resume deadlock and hisi_sas disk-wake race [ Upstream
Commit: e50a6523a603594a6d92cdecfe11997d639410a3
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=e50a6523a603594a6d92cdecfe11997d639410a3

Changed files:
  drivers/scsi/hisi_sas/hisi_sas_v3_hw.c
  drivers/scsi/libsas/sas_init.c
  include/scsi/libsas.h

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=e50a6523a603594a6d92cdecfe11997d639410a3

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

The original Linux kernel CVE announcement for CVE-2026-74555 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-74555

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).