[CVE-2026-97613][LOW] net: mana: Reserve extra CQ slot for the fence completion CQE

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

CVE: CVE-2026-97613
Priority: LOW
AL-KERNEL base severity: LOW
KPANIC flag: NO
Patch: net: mana: Reserve extra CQ slot for the fence completion CQE
Commit: 62eb52454afcc1d390b8624c5d1ddc92cf382f39
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=62eb52454afcc1d390b8624c5d1ddc92cf382f39
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-97613
Analysis date: Fri, 25 Sep 2026 08:07:13 -0400
ActionableScore: 1
ActionableScore lower bound: 0
Actionable bucket: Ordinary Moderate
Manual review required: NO

Summary:
No one-sentence report phrase was found.

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

The original Linux kernel CVE announcement for CVE-2026-97613 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-97613

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-2026-97613	LOW	https://www.kernelcve.org/list/?q=CVE-2026-97613 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:L';**CWE-400;CWE-667;CWE-703;Other CVSS 'AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '2.5';DESCR 'A logic error in the Microsoft MANA driver can leave no completion queue slot for CQE_RX_OBJECT_FENCE when the RX completion queue is full of packet completions. The missing fence completion causes the driver to wait until timeout while holding the RTNL lock, which can stall network control plane operations and temporarily degrade network availability. For the CVSS the paranoid score uses PR:L because a service account or container with delegated network administration privileges may be able to trigger relevant interface operations. The issue is not directly network reachable because packet traffic alone is not shown to initiate the required fence operation. Impact is limited to denial of service. No memory corruption, information disclosure, integrity impact, or privilege escalation primitive is indicated by the patch.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate (with actual score 1)	YES	REMOTE SIMPLEFIX NETWORK HARDWARE MEMORY PACKET  DECREASED_TO_MODERATE_REGULAR_FROM_MODERATE7_BASED_ON_GUESSCVSS DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_ACTIONABLESCORELESSTHAN3	NO	NO	checked

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

ActionableScore=1
ActionableScoreLower=0
PrimitiveClass=CLASS_C
RealUAF=NO
HostAdminRequired=UNKNOWN
NamespaceScopedPrivilege=UNKNOWN
ImportantCandidate=NO
ManualReview=NO
AutoDowngradeAllowed=YES

1. ActionableScore

* Raw conservative score: 0
* Conservative score: 0
* Raw paranoid score: 1
* Paranoid score: 1
* Final recommended bucket: **Ordinary Moderate**::

No floor or cap was applied.

2. Signal breakdown

Positive signals:

* +1 Availability impact realistic. A lost CQE_RX_OBJECT_FENCE can cause the MANA driver to wait for a timeout while holding RTNL lock. This can temporarily stall network control-plane operations and degrade network availability.

Negative signals:

* -1 Narrow condition for conservative scoring. The failure requires the RX completion queue to be full of packet completions at the time hardware emits an additional fence completion CQE. The commit explicitly describes this as occurring in rare cases.

Paranoid interpretation:

* The +1 temporary availability impact is retained.
* The rare-condition penalty is not applied, because sustained high RX load can plausibly make a full completion queue operationally relevant. This does not establish attacker reachability.

Important non-awarded signals:

* No UAF, double free, stale object, refcount misuse, OOB access, DMA overwrite, or active lifetime violation is established.
* Controlled reclaim, arbitrary write, structured object replacement, callback influence, information disclosure, integrity impact, and privilege escalation are not demonstrated.
* Remote reachability is not established. Packet traffic can contribute to RX CQ pressure, but the supplied evidence does not show that a remote peer can independently initiate MANA_FENCE_RQ or the required fence operation.
* Reliable kernel crash is not demonstrated. The stated consequence is a timeout while RTNL lock is held.
* No additional availability point is awarded because the temporary RTNL stall is the only demonstrated availability consequence.
* No hardware-specific penalty is applied. The code is a MANA NIC driver, but the supplied evidence does not establish physical-only attacker access or genuinely rare hardware as a security-relevant trigger restriction.

3. Reachability analysis

The vulnerable condition requires a system using the Microsoft MANA network driver and an RX completion queue that becomes full when a fence completion is posted.

The supplied patch does not show who can initiate the relevant MANA_FENCE_RQ operation. It may occur as part of driver-managed queue, reset, or lifecycle activity. Therefore, HostAdminRequired is UNKNOWN rather than YES or NO.

The supplied context also does not establish that an attacker can complete the entire sequence from an attacker-controlled network namespace. A namespace-local capability to configure networking would not by itself prove control over the MANA physical device, queue lifecycle, or fence operation. NamespaceScopedPrivilege is therefore UNKNOWN.

A remote party may be able to increase receive traffic and help fill the RX completion queue. However, the patch does not establish that network input alone can invoke the fence operation. This is not directly network-triggerable based on available evidence.

No prior privileged setup is proven beyond the presence of an active MANA device and driver. This is a deployment prerequisite, but not sufficient evidence for a privilege penalty.

4. Primitive and severity interpretation

The exact defect is a completion-queue capacity accounting error. The RX CQ was sized for one completion entry per posted RX WQE, but MANA_FENCE_RQ can produce one additional CQE_RX_OBJECT_FENCE after packet CQEs. If the CQ is already full, the fence completion can be dropped.

The demonstrated result is a driver timeout while RTNL lock remains held. This is an invalid-state and temporary availability issue, not a memory corruption primitive.

There is no active structured stale object, no fixed stale storage access, no cleanup/destructor UAF, and no concrete repeated release or refcount mutation.

PrimitiveClass is CLASS_C because the demonstrated effect is a temporary DoS-like control-plane stall without an independently useful corruption, ownership, authorization, or lifetime primitive.

ImportantCandidate is NO because no meaningful Important-versus-Moderate exploitation leverage remains unresolved. AutoDowngradeAllowed is YES because the patch supports a constrained temporary availability impact only.

Likely operational severity is Low or ordinary Moderate depending on the importance of network-control-plane availability on affected MANA deployments.

5. One-sentence report phrase

A MANA RX completion queue sizing error can drop a fence completion event when the queue is full, causing a timeout while RTNL lock is held and temporarily stalling network control-plane operations.

6. Manual review recommendation

NO MANUAL CHECK NEEDED

The supplied patch establishes a constrained queue-capacity and timeout issue without a memory-corruption, security-boundary, privilege-escalation, or remotely triggerable primitive.

7. Call-site confidence

Call-site confidence: low

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

Patch: net: mana: Reserve extra CQ slot for the fence completion CQE
Commit: 62eb52454afcc1d390b8624c5d1ddc92cf382f39
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=62eb52454afcc1d390b8624c5d1ddc92cf382f39

Commit description:

The RX completion queue is sized to hold exactly one CQE per posted RX WQE.
MANA_FENCE_RQ makes hardware post an additional CQE_RX_OBJECT_FENCE after
the packet CQEs. The current sizing reserves no extra slot for it and in
rare cases, CQ has no guaranteed slot for the fence CQE when it is full of
packet CQEs. This can lead to dropping the fence completion while the
driver waits holding RTNL lock throughout the timeout duration.
Reserve one extra CQE slot for CQE_RX_OBJECT_FENCE. mana_gd_alloc_memory()
requires queue_size to be a power-of-two and at least MANA_PAGE_SIZE;
the reservation pushes cq_size past a power-of-two, so round up the CQ size
in mana_create_rxq().

Cc: stable@vger.kernel.org
Fixes: 6cc7444 ("net: mana: Add RX fencing")
Signed-off-by: Sahil Chandna <sahilchandna@linux.microsoft.com>
Reviewed-by: Haiyang Zhang <haiyangz@microsoft.com>
Link: https://patch.msgid.link/20260901121837.3503240-1-sahilchandna@linux.microsoft.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Changed files:
  drivers/net/ethernet/microsoft/mana/mana_en.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=62eb52454afcc1d390b8624c5d1ddc92cf382f39

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

The original Linux kernel CVE announcement for CVE-2026-97613 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-97613

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:L
  The Best / paranoid CVSS score: 2.5

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: 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).