[CVE-2026-74374][LOW] md/raid1,raid10: fix error-path detection with md_cloned_bio() [ Upstream

[CVE-2026-74374][LOW] md/raid1,raid10: fix error-path detection with md_cloned_bio() [ Upstream

[AL-KERNEL]

CVE: CVE-2026-74374
Priority: LOW
AL-KERNEL base severity: LOW
KPANIC flag: NO
Patch: md/raid1,raid10: fix error-path detection with md_cloned_bio() [ Upstream
Commit: 20fb582c92fd64e5c8bd83c6176264b2794603b7
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=20fb582c92fd64e5c8bd83c6176264b2794603b7
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-74374
Analysis date: Sat, 15 Aug 2026 23:57:40 -0400
ActionableScore: 2
ActionableScore lower bound: 1
Actionable bucket: Ordinary Moderate / Low-like. NO MANUAL CHECK REQUIRED COULD BE AUTOCLOSED
Manual review required: YES

Summary:
md raid1 and raid10 could misdetect the failed bio error path after split and resubmit, causing allocations without emergency memory reserves and potentially leading to a storage deadlock under memory pressure.

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

The original Linux kernel CVE announcement for CVE-2026-74374 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-74374

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: YES

A detailed explanation of the methodology and priority rules is included
at the end of this message.

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

CVE-2026-74374	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-833;**CWE-400;CWE-754;Other CVSS 'AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '4.7';DESCR 'md raid1 and raid10 can misdetect the read error path after a failed bio is split and resubmitted. The code may then allocate memory with GFP_NOIO instead of GFP_NOIO plus __GFP_HIGH while the raid1d or raid10d thread is blocked, which can lead to a deadlock under memory pressure. For the CVSS the PR:L is used in the paranoid score because a local user may be able to generate I/O and memory pressure on a system that already has a failing or degraded RAID device, even if fully controlled reproduction often needs administrator level fault injection. The issue is not network reachable and has no clear memory corruption primitive. Impact is denial of service through blocked storage I/O or degraded system responsiveness, not confirmed privilege escalation.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate / Low-like. NO MANUAL CHECK REQUIRED COULD BE AUTOCLOSED (with actual score 2)	YES	LOCK DEADLOCK DISK SIMPLEFIX ERRORPATH HARDWARE LINUS 	NO	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. NO MANUAL CHECK REQUIRED COULD BE AUTOCLOSED**::

## 2. Signal breakdown

Triggered signals:

* Important filesystem/storage path: +1
  md/raid1 and md/raid10 are storage paths, and deadlock in this path can block I/O.

* Availability impact realistic: +1 in paranoid scoring
  The patch describes a possible deadlock under memory pressure when the error path is not recognized.

Negative or limiting signals:

* Hard or unreliable condition: -1
  Triggering requires failed bio handling, split/resubmit behavior, and memory pressure.

* Requires admin/root or special setup for reliable reproduction: -2 in conservative scoring
  Creating the RAID setup, inducing failed reads, or using fault injection normally requires administrative control.

Not triggered:

* No memory corruption signal
  The patch only changes GFP allocation flags based on better error-path detection.

* No UAF, OOB write, double free, refcount takeover, stale callback, or type confusion.

* No privilege escalation plausible signal.

* No remote/network reachability.

## 3. Reachability analysis

A fully reliable trigger usually requires an md raid1 or raid10 array, a failed read bio that is split and resubmitted, and memory pressure at the time the raid1d or raid10d thread is blocked. In typical deployments, an administrator controls RAID configuration and fault injection, so conservative reachability is privileged. A local unprivileged user may contribute I/O load and memory pressure if the system already has a degraded or failing RAID device, but that is a precondition-dependent DoS scenario rather than a direct unprivileged exploit path. Namespaces or containers do not materially lower the requirements unless the workload can stress the host storage stack and memory pressure on an affected md array.

Call-site confidence: high. The relevant raid1_read_request and raid10_read_request paths are present in the patch.

## 4. Severity interpretation

This behaves like an ordinary Moderate or Low-like availability issue, not an Important-class kernel vulnerability. The realistic impact is storage I/O deadlock or degraded system responsiveness under specific error and memory-pressure conditions. There is no supported memory corruption primitive and no evidence of confidentiality, integrity, or privilege-escalation impact.

## 5. One-sentence report phrase

md raid1 and raid10 could misdetect the failed bio error path after split and resubmit, causing allocations without emergency memory reserves and potentially leading to a storage deadlock under memory pressure.

## 6. Manual review recommendation

NO MANUAL CHECK NEEDED

Reason: this is a constrained storage DoS/deadlock fix with no memory corruption, no remote reachability, no privilege escalation evidence, and significant environmental preconditions.

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

Patch: md/raid1,raid10: fix error-path detection with md_cloned_bio() [ Upstream
Commit: 20fb582c92fd64e5c8bd83c6176264b2794603b7
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=20fb582c92fd64e5c8bd83c6176264b2794603b7

Changed files:
  drivers/md/raid1.c
  drivers/md/raid10.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=20fb582c92fd64e5c8bd83c6176264b2794603b7

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

The original Linux kernel CVE announcement for CVE-2026-74374 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-74374

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: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: 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).