[CVE-2026-80534][LOW] xfs: fix ilock leak on error in xfs_dq_get_next_id

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

CVE: CVE-2026-80534
Priority: LOW
AL-KERNEL base severity: LOW
KPANIC flag: NO
Patch: xfs: fix ilock leak on error in xfs_dq_get_next_id
Commit: 6401b99a285cd4cfb2949ba44675541b91ad7e4f
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=6401b99a285cd4cfb2949ba44675541b91ad7e4f
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80534
Analysis date: Wed, 26 Aug 2026 12:11:16 -0400
ActionableScore: 2
ActionableScore lower bound: 0
Actionable bucket: Ordinary Moderate / Low-like
Manual review required: NO

Summary:
An error path in xfs_dq_get_next_id() can leak the XFS quota inode ILOCK when xfs_iread_extents() fails, causing later quota operations to hang and resulting in a local denial of service.

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

The original Linux kernel CVE announcement for CVE-2026-80534 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80534

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-2026-80534	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-667;*CWE-833;CWE-755;Other CVSS 'AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '4.7';DESCR 'xfs_dq_get_next_id can leak the quota inode ILOCK when xfs_iread_extents fails, because the error path returns before unlocking the inode. This can leave the quota inode locked and cause later quota operations to hang, resulting in a local denial of service for XFS quota management paths. For the CVSS the PR:L is used in the paranoid case because some environments may delegate quota operations to a reduced capability service account or container root rather than full host administrator access. The issue is not network reachable and requires a local quota control path plus an error condition in extent loading, so AC:H is appropriate. Impact is denial of service only, with no supported evidence of memory corruption, information disclosure, or privilege escalation.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate / Low-like (with actual score 1)	YES	DISK SIMPLEFIX LEAK 	NO	NO	checked

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

ActionableScore=2
ActionableScoreLower=0

## 1. ActionableScore

* Conservative score: 0
* Paranoid score: 2
* Final recommended bucket: **Ordinary Moderate / Low-like**

## 2. Signal breakdown

Conservative signals:

* Important filesystem/storage path: +1. XFS quota inode locking is part of filesystem quota management.
* Availability impact realistic: +1. A leaked quota inode ILOCK can make later quota operations hang.
* Requires admin/root/CAP_* in typical deployments: -2. Quota management and quota iteration paths are normally administrator controlled.
* Hard or unreliable condition: -1. Triggering requires xfs_iread_extents() to fail after the ILOCK is taken, which usually implies metadata read failure, I/O error, corruption, or fault injection.

Conservative total is effectively below zero, normalized to 0.

Paranoid signals:

* Local unprivileged or reduced-privilege delegated trigger: +1. In some environments quota operations may be exposed through a reduced-capability service account, container root, or delegated management component.
* Reliable hang / DoS concern: +1. Once the lock is leaked, later quota operations can block on the locked quota inode.
* Important filesystem/storage path: +1. The bug affects XFS quota handling.
* Hard or unreliable condition: -1. The required xfs_iread_extents() failure makes reliable triggering non-trivial.

Paranoid total: 2.

No memory corruption, UAF, OOB access, refcount corruption, arbitrary write, page-cache corruption, or ownership/COW bypass is supported by the patch.

## 3. Reachability analysis

The bug is local and not network reachable. A realistic trigger requires reaching xfs_dq_get_next_id() through XFS quota operations and also causing xfs_iread_extents() to fail after the quota inode ILOCK has been acquired. In normal deployments, quota management is privileged, so conservative reachability is admin-only. Namespace or container delegation could lower the practical privilege requirement if quota management is exposed to a less-privileged service or container root, but that is environment-specific.

Call-site confidence: medium. The patch and commit message clearly describe the failing error path and lock leak, but the exact userspace call path and privilege gating are not fully shown in the supplied diff.

## 4. Severity interpretation

This behaves like ordinary Moderate or Low-like DoS, not an Important-class vulnerability. The impact is a local hang of quota-related operations due to a leaked inode lock. There is no evidence of memory corruption or privilege escalation. The paranoid interpretation only raises the score slightly because delegated quota management could make the trigger less privileged and the hang may be operationally relevant.

## 5. One-sentence report phrase

An error path in xfs_dq_get_next_id() can leak the XFS quota inode ILOCK when xfs_iread_extents() fails, causing later quota operations to hang and resulting in a local denial of service.

## 6. Manual review recommendation

NO MANUAL CHECK NEEDED

This can be auto-closed for urgent security triage unless the product exposes XFS quota management to untrusted local users or has a known way for non-admin users to induce quota inode extent read failures.

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

Patch: xfs: fix ilock leak on error in xfs_dq_get_next_id
Commit: 6401b99a285cd4cfb2949ba44675541b91ad7e4f
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=6401b99a285cd4cfb2949ba44675541b91ad7e4f

Commit description:

xfs_dq_get_next_id() takes the quota inode ILOCK before calling
xfs_iread_extents().  If xfs_iread_extents() fails, the function returns
immediately without releasing the lock, leaking the quota inode ILOCK.
This can leave the quota inode locked and cause subsequent quota
operations to hang.

Fix this by jumping to a common unlock path on error instead of returning
directly.

Fixes: bda250d ("xfs: rewrite xfs_dq_get_next_id using xfs_iext_lookup_extent")
Cc: stable@vger.kernel.org # v4.12
Signed-off-by: Long Li <leo.lilong@huawei.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_dquot.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=6401b99a285cd4cfb2949ba44675541b91ad7e4f

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

The original Linux kernel CVE announcement for CVE-2026-80534 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80534

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: 0
  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).