[CVE-2026-46299][LOW] hfsplus: fix held lock freed on hfsplus_fill_super() [ Upstream

[CVE-2026-46299][LOW] hfsplus: fix held lock freed on hfsplus_fill_super() [ Upstream

[AL-KERNEL]

CVE: CVE-2026-46299
Priority: LOW
AL-KERNEL base severity: LOW
KPANIC flag: NO
Patch: hfsplus: fix held lock freed on hfsplus_fill_super() [ Upstream
Commit: 3ca80e3012c8be85b4f8d0d20eac8d3b17ff257e
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=3ca80e3012c8be85b4f8d0d20eac8d3b17ff257e
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-46299
Analysis date: Mon, 08 Jun 2026 15:01:14 -0400
ActionableScore: 0
ActionableScore lower bound: unknown
Actionable bucket: Ordinary Moderate / Low-like
Manual review required: NO

Summary:
No one-sentence report phrase was found.

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

The original Linux kernel CVE announcement for CVE-2026-46299 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-46299

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-2026-46299	LOW	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:N/I:N/A:H';CWE-667;*CWE-772;CWE-703;Other CVSS 'AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '4.7';DESCR 'HFSPLUS mount error handling can free tree data while tree_lock is still held because hfsplus_fill_super() may jump to cleanup after hfsplus_cat_build_key() fails without releasing the search structure. This is primarily a local cleanup and locking bug in the mount path and the observed symptom is a held lock freed warning. For the CVSS the PR:L is used for the paranoid score because some deployments may delegate mount capability to a container root, automount service, or reduced privilege local account, while the typical base case requires administrative mount privileges. The issue is not network reachable and requires local interaction with an HFSPLUS filesystem image or mount operation. Impact is expected to be denial of service or diagnostic warning behavior rather than confidentiality or integrity compromise.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate / Low-like (with actual score 0) 	MAYBE	DISK INIT ERRORPATH UAF KERNEL_PANIC_PLUS_UAF HARDWARE LINUS  DECREASED_TO_MODERATE_REGULAR_FROM_MODERATE7_BASED_ON_GUESSCVSS_AND_CIANNH DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_ACTIONABLESCORELESSTHAN3	-	-	checked

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

ActionableScore=0

1. ActionableScore
* Conservative score: 0
* Paranoid score: 1
* Final recommended bucket: **Ordinary Moderate / Low-like**

2. Signal breakdown
* Requires admin/root/CAP_SYS_ADMIN in typical deployments: -2. Triggering requires mounting an HFSPLUS filesystem, which normally requires administrative mount privileges.
* Hard or unreliable special condition required: -1. The demonstrated trigger required GDB manipulation of max_unistr_len to force the error path, so natural reachability from a crafted image is not clearly demonstrated.
* Rare AND difficult-to-reach subsystem/configuration: -1. HFSPLUS is a niche filesystem and the vulnerable path is an uncommon mount error path.
* Reliable kernel crash / strong DoS: +0 conservative. The observed result is a held lock freed warning under lockdep, not a demonstrated reliable panic on production kernels.
* Paranoid local delegated trigger: +1. In environments where mount capability is delegated to container root, automount helpers, or reduced privilege services, the practical PR may be lower than full host root.

3. Reachability analysis
The bug is triggered during hfsplus_fill_super() while mounting an HFSPLUS filesystem. In normal deployments, this requires CAP_SYS_ADMIN or equivalent control over mount operations and access to a block device or filesystem image. It is not network reachable. User namespaces or containerized environments may lower the practical privilege boundary if HFSPLUS mounting is delegated, but this is not the common default. The error path appears narrow and was confirmed by forcing an internal parameter with GDB, so realistic exploitation conditions are weak.

4. Severity interpretation
This behaves like a low-end Moderate or Low-like cleanup/locking bug rather than an Important-class vulnerability. The patch fixes a missing hfs_find_exit() on an error path, preventing tree_lock from remaining held when the tree object is freed. There is no demonstrated UAF dereference, attacker-controlled overwrite, information leak, or privilege-escalation primitive. The theoretical risk is local DoS or diagnostic warning behavior, while realistic exploitation evidence is limited.

5. One-sentence report phrase
An HFSPLUS mount error path can free tree data while tree_lock is still held, causing a held lock freed warning and possible local DoS under uncommon mount failure conditions.

6. Manual review recommendation
NO MANUAL CHECK NEEDED. The issue requires privileged or delegated mount access, is not remotely reachable, shows no concrete memory corruption primitive beyond a lock cleanup bug, and the practical impact appears limited to warning or local availability degradation.

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

Patch: hfsplus: fix held lock freed on hfsplus_fill_super() [ Upstream
Commit: 3ca80e3012c8be85b4f8d0d20eac8d3b17ff257e
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=3ca80e3012c8be85b4f8d0d20eac8d3b17ff257e

Changed files:
  fs/hfsplus/super.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=3ca80e3012c8be85b4f8d0d20eac8d3b17ff257e

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

The original Linux kernel CVE announcement for CVE-2026-46299 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-46299

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: unknown
  Paranoid ActionableScore: 0

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).