[CVE-2026-99029][LOW] net: sparx5: free the matchall entry on destroy

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

CVE: CVE-2026-99029
Priority: LOW
AL-KERNEL base severity: LOW
KPANIC flag: NO
Patch: net: sparx5: free the matchall entry on destroy
Commit: fa0c27d9e17ee2e46d4b8274a6fde706f0d6725e
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=fa0c27d9e17ee2e46d4b8274a6fde706f0d6725e
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-99029
Analysis date: Tue, 27 Oct 2026 01:08:27 -0400
ActionableScore: 1
ActionableScore lower bound: unknown
Actionable bucket: Ordinary Moderate
Manual review required: NO

Summary:
Repeated deletion of Sparx5 offloaded matchall filters leaks one bookkeeping allocation per filter, with no demonstrated memory corruption or host-wide exhaustion.

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

The original Linux kernel CVE announcement for CVE-2026-99029 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-99029

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.

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AL-KERNEL CLASSIFICATION RESULT
======================================================================

CVE-2026-99029	LOW	https://www.kernelcve.org/list/?q=CVE-2026-99029 CHECK WITH IMPACT FROM ORIG NN IMPORTANT | AEGIS IMPACT MODERATE AEGIS_AS=1 LEGACY=LOW RESULT=DIFF (final Legacy and Aegis differ; FINAL: LOW, Aegis: MODERATE)	Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L';*CWE-401;*CWE-772;Other CVSS 'AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '3.3';DESCR 'A persistent memory leak occurs because sparx5_tc_matchall_destroy removes a matchall entry from mall_entries but does not free the allocated structure. Repeated creation and deletion of offloaded mirror or goto filters retains one small kernel allocation per cycle. For the CVSS the PR:H value reflects that reliable triggering normally requires CAP_NET_ADMIN and control of traffic control filters on supported Sparx5 or LAN969x hardware. The issue is not remotely triggerable by packet traffic. The demonstrated primitive is resource retention with low availability impact and there is no evidence of UAF, out of bounds access, information disclosure, or direct kernel corruption. Automated impact decision path. The original SimpleNet classifier selected IMPORTANT. The primary LLM estimated paranoid CVSS 3.3 and the production ActionableScore returned 1 with recommendation Ordinary Moderate. The production rules then evaluated CVSS thresholds and ActionableScore thresholds. Recorded rule transitions were CVSS and initial triage stage IMPORTANT to MODERATE_KPANIC because the CVSS score, vector or bug class threshold rule was applied. ActionableScore thresholds stage MODERATE_KPANIC to LOW because the ActionableScore threshold rule was applied. final reconciliation stage LOW to LOW because KP specialist did not establish a qualifying panic and the cross model evidence reconciliation rule was applied. The legacy KP specialist has no review artifact for this run. The legacy FD or DH downgrade specialist has no review artifact for this run. Exact triggered rule markers were LOWERED_FROM_HIGH_BASED_ON_GUESSCVSS and DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN4 and DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_ACTIONABLESCORELESSTHAN3 and KPANIC_UNSUPPORTED_REMOVED and V64_AEGIS_UNSUPPORTED_PROMOTION_BLOCKED. The independent weaker Aegis shadow evaluated CVSS 2.4 and ActionableScore 1 with primitive class CLASS_C and manual review REQUIRED. Its independently reconciled impact was MODERATE. The models disagreed but the aggregation rules retained the production result. The final reported impact is LOW.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate (with actual score 1)	MAYBE	REMOTE SIMPLEFIX LEAK NETWORK LINUS LOWERED_FROM_HIGH_BASED_ON_GUESSCVSS DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN4 DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_ACTIONABLESCORELESSTHAN3 KPANIC_UNSUPPORTED_REMOVED V64_AEGIS_UNSUPPORTED_PROMOTION_BLOCKED	-	-	checked

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

ActionableScore=1
PrimitiveClass=CLASS_C
RealUAF=NO
HostAdminRequired=UNKNOWN
NamespaceScopedPrivilege=UNKNOWN
ImportantCandidate=NO
ManualReview=NO
AutoDowngradeAllowed=YES
RequiresHostUID0=UNKNOWN
AuthorizationDecisionBypass=NO
ProtectedResourceImpact=NONE
B4PendingReview=NO
B4PendingConfirmed=NO

1. ActionableScore

* Raw base score: 1.
* Conservative score: 1.
* Raw paranoid score: 1.
* Paranoid score: 1.
* No floor or cap applied.
* Final recommended bucket: **Ordinary Moderate**::

2. Signal breakdown

* +1 Concrete persistent kernel resource leak: `sparx5_tc_matchall_replace()` allocates each entry, while destroy previously performed only `list_del()`; the added `kfree(entry)` confirms the allocation was permanently lost.
* +0 Strong DoS/resource exhaustion: repeated leakage was reproduced with kmemleak, but host-wide exhaustion, isolation bypass, or persistent service failure is not shown.
* No UAF, OOB access, active-state corruption, shared-backing write, authorization bypass, disclosure, or protected-state modification is evidenced.
* No availability point: the supplied evidence does not show a crash or material exhaustion.
* No privilege penalty: CAP_NET_ADMIN is indicated, but the exact governing namespace and whether host-admin-equivalent authority is required are not established strongly enough for subtraction.
* No hardware penalty: supported Sparx5/LAN969x hardware is required, but the evidence does not establish the “rare physical access” condition needed for a numeric penalty.

3. Reachability analysis

The trigger is repeated creation and deletion of offloaded matchall mirror or goto traffic-control filters on a supported Sparx5/LAN969x device. Packet traffic alone cannot trigger it. Traffic-control configuration generally requires CAP_NET_ADMIN, but the supplied source does not resolve whether the complete operation is governed by the device’s owning network namespace or necessarily requires host/init-namespace authority. Thus both effective host-admin and namespace-scoped reachability remain unknown. Compatible hardware and an offload-capable device are prerequisites; no race is involved.

4. Primitive and severity reading

The exact primitive is a small, repeatable heap allocation leak caused by unlinking an entry without freeing it. There is no stale use or post-lifetime access, so this is not a UAF and no repeated release exists. The demonstrated consequence is retained kernel memory; meaningful host exhaustion is unproven. This is CLASS_C resource/availability behavior, with no Important-preserving primitive and no reason to block an ordinary Moderate downgrade.

5. One-sentence report phrase

Repeated deletion of Sparx5 offloaded matchall filters leaks one bookkeeping allocation per filter, with no demonstrated memory corruption or host-wide exhaustion.

6. Manual review advice

NO MANUAL CHECK NEEDED

The patch and kmemleak reproduction establish only a straightforward resource leak with limited security impact.

7. Call-site confidence

Call-site confidence: high

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

Patch: net: sparx5: free the matchall entry on destroy
Commit: fa0c27d9e17ee2e46d4b8274a6fde706f0d6725e
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=fa0c27d9e17ee2e46d4b8274a6fde706f0d6725e

Commit description:

sparx5_tc_matchall_replace() allocates a struct sparx5_mall_entry for
every offloaded matchall filter and adds it to sparx5->mall_entries.
sparx5_tc_matchall_destroy() removes the entry from the list, but never
frees it, so the entry of every deleted mirror and goto matchall filter
is leaked.

Free the entry after unlinking it.

The leak was discovered by an AI code review agent, and reproduced with
kmemleak on a lan969x EV board (EV23X71A) by repeatedly adding and
deleting matchall mirror and goto filters. With the fix, kmemleak no
longer reports the leak.

Cc: stable@vger.kernel.org
Fixes: 1ede4ac ("net: sparx5: add bookkeeping code for matchall rules")
Signed-off-by: Daniel Machon <daniel.machon@microchip.com>
Link: https://patch.msgid.link/20261007-sparx5-matchall-kfree-net-v1-1-c8918685b337@microchip.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Changed files:
  drivers/net/ethernet/microchip/sparx5/sparx5_tc_matchall.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=fa0c27d9e17ee2e46d4b8274a6fde706f0d6725e

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

The original Linux kernel CVE announcement for CVE-2026-99029 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-99029

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:L/PR:H/UI:N/S:U/C:N/I:N/A:L
  The Best / paranoid CVSS vector: AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L
  The Best / paranoid CVSS score: 3.3

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: 1

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).