[CVE-2026-74754][LOW] scsi: core: pair EH runtime PM get and put [ Upstream

[CVE-2026-74754][LOW] scsi: core: pair EH runtime PM get and put [ Upstream

[AL-KERNEL]

CVE: CVE-2026-74754
Priority: LOW
AL-KERNEL base severity: LOW
KPANIC flag: NO
Patch: scsi: core: pair EH runtime PM get and put [ Upstream
Commit: e83eed1bea142c8fe852fd53156845b88252ecd8
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=e83eed1bea142c8fe852fd53156845b88252ecd8
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-74754
Analysis date: Wed, 26 Aug 2026 12:32:08 -0400
ActionableScore: 2
ActionableScore lower bound: unknown
Actionable bucket: Ordinary Moderate / Low-like
Manual review required: NO

Summary:
A race between SCSI error handling and UFS runtime power management can unbalance runtime PM get and put operations, causing a usage count underflow and possible local storage availability degradation.

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

The original Linux kernel CVE announcement for CVE-2026-74754 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-74754

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-2026-74754	LOW	CHECK WITH IMPACT FROM ORIG NN LOW	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-911;CWE-667;Other CVSS 'AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '4.7';DESCR 'SCSI error handling can race with the UFS power management path because shost eh_noresume was checked separately before runtime PM get and runtime PM put. If the flag changes during one EH iteration, the EH thread can skip scsi_autopm_get_host on entry but still call scsi_autopm_put_host on exit, causing an unmatched runtime PM put and a runtime PM usage count underflow. For the CVSS the PR:L is used because a local process or local workload is needed to interact with the storage stack and make the PM and EH paths relevant, but full administrative privileges are not clearly required for the practical trigger model. The issue is not network reachable and requires a timing window between PM state handling and SCSI error recovery. Impact is denial of service or device availability degradation, not privilege escalation or information disclosure.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate / Low-like (with actual score 2)	YES	OOB DANGER ERRORPATH HARDWARE LINUS  DECREASED_TO_MODERATE_REGULAR_FROM_MODERATE7_BASED_ON_GUESSCVSS_AND_CIANNH DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_ACTIONABLESCORELESSTHAN3	NO	NO	checked

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

ActionableScore=2

## 1. ActionableScore

* Conservative score: 2
* Paranoid score: 3
* Final recommended bucket: **Ordinary Moderate / Low-like**::

## 2. Signal breakdown

Triggered signals:

* Local unprivileged trigger: +1
  A local workload interacting with UFS/SCSI storage can plausibly make PM and SCSI EH paths relevant. Full administrative privileges are not clearly required for the practical trigger model.

* Important filesystem/storage path: +1
  This affects SCSI core error handling and UFS runtime PM interaction, which is an important storage availability path.

* Hard or unreliable race / special timing required: -1
  The bug requires a timing window where the PM path flips `shost->eh_noresume` while the SCSI EH thread is in one iteration.

* Availability impact realistic: +1
  An unmatched runtime PM put can cause runtime PM usage count underflow and storage device availability degradation.

Not awarded:

* No remote/network reachability.
* No generic memory corruption.
* No UAF, double-free, OOB write, stale callback, refcount takeover, or arbitrary write.
* No confidentiality or integrity impact supported by the patch.
* No plausible privilege escalation primitive.

Conservative total: 1 + 1 - 1 + 1 = 2.

Paranoid total: 3 if treating runtime PM underflow as stronger persistent storage DoS, but still no memory corruption or LPE signal.

## 3. Reachability analysis

The likely trigger is local and workload-dependent. A user or process must cause storage activity and error handling while UFS runtime power-management transitions are occurring. Namespaces do not obviously make this more reachable, because the vulnerable path is in host storage error handling rather than a namespaced control API. The path is relevant on systems using affected SCSI/UFS runtime PM behavior, but exploitation requires a race between PM state changes and SCSI EH processing.

Call-site confidence: high, because the patch shows both the SCSI EH caller logic and the UFS writer of `eh_noresume`.

## 4. Severity interpretation

This behaves like an ordinary Moderate or Low-like availability issue, not an Important-class vulnerability. The bug is a race and PM reference accounting mismatch. The demonstrated consequence is runtime PM usage count underflow and possible device availability degradation. There is no supported memory corruption primitive and no realistic evidence of privilege escalation.

## 5. One-sentence report phrase

A race between SCSI error handling and UFS runtime power management can unbalance runtime PM get and put operations, causing a usage count underflow and possible local storage availability degradation.

## 6. Manual review recommendation

NO MANUAL CHECK NEEDED

Reason: the issue is local, timing-dependent, storage-device specific, and the patch supports availability impact only. No memory corruption, privilege escalation, information disclosure, or security-boundary bypass is visible.

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

Patch: scsi: core: pair EH runtime PM get and put [ Upstream
Commit: e83eed1bea142c8fe852fd53156845b88252ecd8
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=e83eed1bea142c8fe852fd53156845b88252ecd8

Changed files:
  drivers/scsi/scsi_error.c
  drivers/ufs/core/ufshcd.c
  include/scsi/scsi_host.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=e83eed1bea142c8fe852fd53156845b88252ecd8

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

The original Linux kernel CVE announcement for CVE-2026-74754 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-74754

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:L/UI:N/S:U/C:N/I:N/A:L
  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: 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).