[CVE-2026-43063][MODERATE 7.0] xfs: don't irele after failing to iget in xfs_attri_recover_work

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

CVE: CVE-2026-43063
Priority: MODERATE 7.0
AL-KERNEL base severity: MODERATE
KPANIC flag: NO
Patch: xfs: don't irele after failing to iget in xfs_attri_recover_work
Commit: b5c5a50c2f513d4a13a6763564a07b470e69cc5a
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=b5c5a50c2f513d4a13a6763564a07b470e69cc5a
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-43063
Analysis date: Tue, 09 Jun 2026 17:51:24 -0400
ActionableScore: 5
ActionableScore lower bound: 3
Actionable bucket: Actionable Moderate at minimum
Manual review required: YES

Summary:
XFS xattr log recovery may call `xfs_irele()` on an invalid inode pointer after a failed recovery iget, causing a local recovery-time crash and requiring manual review due to weak memory-corruption potential.

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

The original Linux kernel CVE announcement for CVE-2026-43063 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-43063

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 7.0
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-2026-43063	MODERATE	CHECK	Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:H';CWE-824;CWE-825;**CWE-476;Other CVSS 'AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '5.8';DESCR 'XFS attribute log recovery can call xfs_irele(ip) after xlog_recovery_iget() fails even though ip is not a valid inode pointer on that error path. This creates an invalid or dangling pointer release during recovery and can crash the kernel when a corrupted or attacker influenced XFS log is replayed. For the CVSS the PR:L is used in the paranoid score because a local user may be able to influence logged xattr operations before recovery in some deployments, while direct mount control is usually administrative. The issue is not network reachable and is triggered through local filesystem recovery rather than remote traffic. Impact is at least denial of service via kernel crash and in worst case may allow limited confidentiality or integrity impact due to memory corruption and should be reviewed manually.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Actionable Moderate at minimum (with actual score 4)	YES	DANGER DISK  DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN5	YES	NO	checked

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

ActionableScore=5
ActionableScoreLower=3

## 1. ActionableScore

* Conservative score: 3
* Paranoid score: 5
* Final recommended bucket: **Actionable Moderate at minimum**::

## 2. Signal breakdown

Conservative signals:

* Memory corruption, weak/indirect corruption candidate: +1
  `xfs_irele(ip)` may be called when `ip` was not set to a valid inode pointer after `xlog_recovery_iget*()` failure.
* Real lifetime corruption: +1
  This is an invalid inode reference release path, potentially involving a dangling or bogus pointer.
* Reliable kernel crash / strong DoS: +1
  The likely practical effect is crash or recovery failure during XFS log replay.
* Important filesystem/storage path: +1
  The bug is in XFS log recovery for xattr intent items.
* Requires admin/root/CAP_SYS_ADMIN in typical deployments: -2
  Direct triggering normally requires mounting or replaying an affected XFS filesystem, which is usually administrative.

Conservative total: 3

Paranoid additional signals:

* Local unprivileged influence: +1
  A local user may be able to influence xattr log contents before crash/recovery on systems where they can create or modify extended attributes.
* Weak LPE concern: +1
  The primitive is not a plain NULL dereference. It is an invalid or dangling object pointer passed into inode reference release code, so limited corruption risk is plausible but not demonstrated.

Paranoid total: 5

## 3. Reachability analysis

The bug is triggered during XFS log recovery, not through network traffic. In the normal case, an attacker needs control over a filesystem image, mount/recovery operation, or the ability to influence XFS xattr log intent state before a crash and later recovery. Direct mounting is typically restricted to root or `CAP_SYS_ADMIN`, so the conservative privilege model is high privilege. The paranoid model treats this as potentially local lower privilege influence because ordinary users may be able to perform xattr operations on writable XFS filesystems, while the actual recovery trigger still depends on crash or remount conditions.

Namespaces and containers generally do not make XFS host filesystem recovery directly available to unprivileged users, but delegated mount or storage-management setups could reduce the effective privilege boundary. The path is not remote reachable. XFS is a common production filesystem, and recovery/journal replay is an important storage integrity path.

## 4. Severity interpretation

This behaves more like an actionable Moderate than an ordinary low-risk crash. The realistic impact is local DoS through kernel crash or failed filesystem recovery. The theoretical risk is higher because the code may release an invalid inode pointer, which is a memory-safety issue in a trusted filesystem recovery path. However, the patch does not show attacker-controlled reclaim, arbitrary write, callback control, or a reliable privilege escalation primitive, so Important severity is not strongly demonstrated.

## 5. One-sentence report phrase

XFS xattr log recovery may call `xfs_irele()` on an invalid inode pointer after a failed recovery iget, causing a local recovery-time crash and requiring manual review due to weak memory-corruption potential.

## 6. Manual review recommendation

MANUAL CHECK REQUIRED

Reason: this is not merely a validation cleanup or resource leak. It is an invalid pointer release in XFS recovery code, with realistic DoS and plausible but unproven corruption impact.

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

Patch: xfs: don't irele after failing to iget in xfs_attri_recover_work
Commit: b5c5a50c2f513d4a13a6763564a07b470e69cc5a
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=b5c5a50c2f513d4a13a6763564a07b470e69cc5a

Commit description:

xlog_recovery_iget* never set @ip to a valid pointer if they return
an error, so this irele will walk off a dangling pointer.  Fix that.

Cc: stable@vger.kernel.org # v6.10
Fixes: ae673f5 ("xfs: record inode generation in xattr update log intent items")
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Long Li <leo.lilong@huawei.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Carlos Maiolino <cmaiolino@redhat.com>
Signed-off-by: Carlos Maiolino <cem@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Changed files:
  fs/xfs/xfs_attr_item.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=b5c5a50c2f513d4a13a6763564a07b470e69cc5a

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

The original Linux kernel CVE announcement for CVE-2026-43063 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-43063

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:L/I:L/A:H
  The Best / paranoid CVSS score: 5.8

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: 3
  Paranoid ActionableScore: 5

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 7.0

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).