[CVE-2026-53207][LOW] mm/memory-failure: fix hugetlb_lock AA deadlock in get_huge_page_for_hwpoison [ Upstream

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

CVE: CVE-2026-53207
Priority: LOW
AL-KERNEL base severity: LOW
KPANIC flag: NO
Patch: mm/memory-failure: fix hugetlb_lock AA deadlock in get_huge_page_for_hwpoison [ Upstream
Commit: fc3ff42cb0cbf947e4600ae9761c3783760050e2
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=fc3ff42cb0cbf947e4600ae9761c3783760050e2
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-53207
Analysis date: Thu, 25 Jun 2026 05:58:00 -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-2026-53207 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-53207

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-2026-53207	LOW	CHECK	Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H';*CWE-833;CWE-667;CWE-362;Other CVSS 'AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '4.4';DESCR 'A recursive locking deadlock can occur in the hugetlb hardware poison path when two MADV_HWPOISON operations race on the same hugetlb page while a concurrent unmap drops the last mapping reference. The vulnerable path can call folio_put while hugetlb_lock is still held, and if the folio refcount reaches zero then free_huge_folio tries to acquire hugetlb_lock again on the same CPU. This results in a local denial of service through a CPU or system lockup. For the CVSS the PR:H is used because reliable triggering requires privileged MADV_HWPOISON fault injection access such as CAP_SYS_ADMIN on the host. The issue is not network reachable and there is no concrete evidence of confidentiality or integrity impact from the patch context.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate / Low-like (with actual score 0)	YES	LOCK DEADLOCK DANGER INIT RACE HARDWARE  DECREASED_TO_MODERATE_REGULAR_FROM_MODERATE7_BASED_ON_GUESSCVSS DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_ACTIONABLESCORELESSTHAN3	YES	NO	checked

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

ActionableScore=0

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

2. Signal breakdown
* Reliable kernel crash / strong DoS: +1. The bug can cause recursive hugetlb_lock self-deadlock and local CPU or system lockup.
* Hard or unreliable race / special timing required: -1. Triggering requires two concurrent MADV_HWPOISON calls on the same hugetlb page plus a concurrent unmap window.
* Requires admin/root/CAP_SYS_ADMIN in typical deployments: -2. MADV_HWPOISON is a privileged fault-injection interface and reliable triggering normally requires CAP_SYS_ADMIN.
* No memory corruption bonus. The patch fixes lock ordering around folio_put and does not show UAF, OOB write, stale callback, type confusion, arbitrary write, or attacker-controlled reuse.
* No confidentiality or integrity impact. The demonstrated primitive is deadlock only.

3. Reachability analysis
The trigger is local and privileged through madvise(MADV_HWPOISON) on hugetlb memory. It is not network reachable. Containers or namespaces do not normally make this unprivileged because MADV_HWPOISON requires elevated capability on the host or an equivalently privileged environment. The path also depends on hugetlb and memory-failure or hwpoison functionality, so practical exposure is limited to systems where privileged fault injection against hugetlb pages is available.

4. Severity interpretation
This behaves like an ordinary Moderate or Low-like kernel DoS issue, not an Important-class vulnerability. Theoretical impact is a local denial of service from a spinlock self-deadlock. Realistic exploitation evidence does not support privilege escalation, data corruption, information disclosure, or a stronger memory corruption primitive.

5. One-sentence report phrase
A privileged local user able to invoke MADV_HWPOISON on hugetlb pages can race concurrent poison operations with unmap and trigger a hugetlb_lock self-deadlock, causing a local denial of service.

6. Manual review recommendation
NO MANUAL CHECK NEEDED. The patch and commit describe a privileged local deadlock with no concrete memory corruption or security-boundary bypass primitive.

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

Patch: mm/memory-failure: fix hugetlb_lock AA deadlock in get_huge_page_for_hwpoison [ Upstream
Commit: fc3ff42cb0cbf947e4600ae9761c3783760050e2
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=fc3ff42cb0cbf947e4600ae9761c3783760050e2

Changed files:
  include/linux/hugetlb.h
  include/linux/mm.h
  mm/hugetlb.c
  mm/memory-failure.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=fc3ff42cb0cbf947e4600ae9761c3783760050e2

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

The original Linux kernel CVE announcement for CVE-2026-53207 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-53207

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:L/PR:H/UI:N/S:U/C:N/I:N/A:H
  The Best / paranoid CVSS score: 4.4

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).