[CVE-2026-80538][MODERATE REGULAR] xfs: propagate errors from xfs_rtginode_load

[AL-KERNEL <alkernel@kernelcve.org>]

CVE: CVE-2026-80538
Priority: MODERATE REGULAR
AL-KERNEL base severity: MODERATE
KPANIC flag: NO
Patch: xfs: propagate errors from xfs_rtginode_load
Commit: ec19cea4ef1ce9d6e2e3f7e9e7bf88ede31176e7
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=ec19cea4ef1ce9d6e2e3f7e9e7bf88ede31176e7
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80538
Analysis date: Wed, 26 Aug 2026 13:53:56 -0400
ActionableScore: 3
ActionableScore lower bound: 1
Actionable bucket: Borderline, manual review recommended
Manual review required: YES

Summary:
XFS realtime growfs could ignore non-ENOENT xfs_rtginode_load failures and continue with an unset realtime group inode, creating a local administrative filesystem integrity and availability risk without evidence of remote reachability or privilege escalation.

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

The original Linux kernel CVE announcement for CVE-2026-80538 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80538

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: MODERATE REGULAR
Manual review required: YES

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-2026-80538	MODERATE	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:H/UI:N/S:U/C:N/I:H/A:H';CWE-252;CWE-703;*CWE-664;Other CVSS 'AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:L/A:L';BEST CVSS score: '5.7';DESCR 'XFS realtime growfs could continue after xfs_rtginode_load returned an I/O, allocation, or corruption error because xfs_rtginode_ensure treated every non ENOENT error as success. This can leave the realtime group inode unset while later growfs logic assumes that the inode was loaded, creating a risk of filesystem metadata inconsistency or a crash during administrative resize operations. For the CVSS the PR:H is used because reliable triggering normally requires administrative control over XFS growfs or equivalent filesystem management privileges. The issue is not network reachable and is triggered through local filesystem control plane operations rather than file data access or packet traffic. Impact is mainly availability and integrity risk for the affected filesystem, with no direct evidence of an information disclosure or privilege escalation primitive.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Borderline, manual review recommended (with actual score 2) 	MAYBE	DANGER DISK SIMPLEFIX LINUS  DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN5	-	-	checked

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ACTIONABLESCORE ANALYSIS
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ActionableScore=3
ActionableScoreLower=1

## 1. ActionableScore

* Conservative score: 1
* Paranoid score: 3
* Final recommended bucket: **Borderline, manual review recommended**::

## 2. Signal breakdown

Conservative signals:

* Important filesystem/storage path: +1. XFS growfs and realtime group inode handling are filesystem metadata paths.
* Integrity impact plausible: +1. Continuing growfs with an unset realtime group inode can plausibly create filesystem metadata inconsistency.
* Availability impact realistic: +1. A failed metadata operation may lead to growfs failure, filesystem errors, shutdown, or crash-like operational impact.
* Requires admin/root/CAP_SYS_ADMIN in typical deployments: -2. Reliable triggering requires XFS growfs or equivalent filesystem management privileges.
* Special preconditions required: -1. The bad path requires xfs_rtginode_load to fail with I/O, allocation, or corruption error during growfs.

Paranoid additions:

* Broad/common filesystem relevance: +1. XFS is widely deployed, even though realtime growfs with per-RTG files is more specific.
* Stronger filesystem DoS concern: +1. If later growfs code dereferences or relies on the missing realtime group inode, the result can be more than a clean failure and may require recovery action.

Not awarded:

* No remote reachability.
* No local unprivileged trigger.
* No generic memory corruption primitive shown.
* No UAF, OOB write, double free, refcount abuse, or callback control.
* No privilege escalation plausibility beyond filesystem metadata integrity concerns.

Call-site confidence: medium. The patch shows the changed helper and the growfs context, but not all downstream users of the unset realtime group inode.

## 3. Reachability analysis

The bug is reachable through XFS growfs handling, not through ordinary file reads or writes. In normal deployments, growfs requires administrative privileges such as CAP_SYS_ADMIN or root-equivalent filesystem management control. Namespaces or containers do not usually make this unprivileged unless the environment deliberately delegates filesystem administration for the affected mount. The path is not network reachable. Realistic triggering also depends on an I/O, allocation, or corruption error from xfs_rtginode_load during realtime growfs, so exploitation conditions are specialized.

## 4. Severity interpretation

This behaves like a low-to-borderline actionable filesystem metadata bug rather than an Important-class kernel memory corruption issue. The theoretical impact is filesystem integrity or availability loss if growfs continues after a failed inode load. The realistic evidence does not show privilege escalation, information disclosure, arbitrary write, UAF, or attacker-controlled memory corruption. Manual review is still useful because filesystem metadata bugs can have persistent operational impact even when CVSS and exploitability are limited by PR:H.

## 5. One-sentence report phrase

XFS realtime growfs could ignore non-ENOENT xfs_rtginode_load failures and continue with an unset realtime group inode, creating a local administrative filesystem integrity and availability risk without evidence of remote reachability or privilege escalation.

## 6. Manual review recommendation

MANUAL CHECK RECOMMENDED

Reason: the actionable score is low, but this is an XFS metadata error-handling path where the conservative impact may understate operational integrity risk.

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

Patch: xfs: propagate errors from xfs_rtginode_load
Commit: ec19cea4ef1ce9d6e2e3f7e9e7bf88ede31176e7
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=ec19cea4ef1ce9d6e2e3f7e9e7bf88ede31176e7

Commit description:

xfs_rtginode_ensure() treats every xfs_rtginode_load() error other than
-ENOENT as success.  This can leave the realtime group inode unset after an
I/O, allocation, or corruption error.  Growfs then continues as though the
inode had been loaded.

Only -ENOENT means that the inode needs to be created.  Return all other
errors to the growfs caller.

Fixes: ae897e0 ("xfs: support creating per-RTG files in growfs")
Cc: stable@vger.kernel.org
Signed-off-by: Guanghui Yang <3497809730@qq.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>
Signed-off-by: Carlos Maiolino <cem@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Changed files:
  fs/xfs/xfs_rtalloc.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=ec19cea4ef1ce9d6e2e3f7e9e7bf88ede31176e7

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

The original Linux kernel CVE announcement for CVE-2026-80538 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80538

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:H/UI:N/S:U/C:N/I:H/A:H
  The Best / paranoid CVSS score: 5.7

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: 3

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: MODERATE
KPANIC detected for this report: NO
Published priority for this report (same as in Subject): MODERATE REGULAR

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).