[CVE-2026-74623][LOW] net: atlantic: free stranded TX buffers on ring deinit

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

CVE: CVE-2026-74623
Priority: LOW
AL-KERNEL base severity: LOW
KPANIC flag: NO
Patch: net: atlantic: free stranded TX buffers on ring deinit
Commit: 307d80193b4a4a75b8dc4e0d3162be3755abbed7
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=307d80193b4a4a75b8dc4e0d3162be3755abbed7
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-74623
Analysis date: Sat, 22 Aug 2026 17:30:00 -0400
ActionableScore: 2
ActionableScore lower bound: 0
Actionable bucket: Ordinary Moderate / Low-like
Manual review required: NO

Summary:
The atlantic driver can leak stranded TX skb or xdp_frame references during ring teardown under TX or XDP_TX load, causing persistent resource leakage and possible DoS, but triggering typically requires local network device management privileges and no memory corruption or privilege escalation primitive is evident.

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ABOUT THIS REPORT
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The original Linux kernel CVE announcement for CVE-2026-74623 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-74623

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
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CVE-2026-74623	LOW	CHECK WITH IMPACT FROM ORIG NN LOW	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:H';*CWE-772;*CWE-401;CWE-404;**CWE-400;Other CVSS 'AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '5.5';DESCR 'The atlantic driver can leak TX resources during ring teardown because aq_vec_deinit used aq_ring_tx_clean, which frees only a limited clean budget and stops at a hardware head that no longer advances after the device and NAPI are stopped. Under TX or XDP_TX load, descriptors still present between sw_head and sw_tail can keep skb or xdp_frame references alive after the buffer ring is freed, causing a persistent memory leak. In configurations with page_pool backed XDP_TX frames, a single stranded frame can keep the page_pool inflight count nonzero and cause repeated stalled pool shutdown warnings. For the CVSS the PR:L is used for the paranoid score because some deployments may delegate network administration or XDP control to a reduced capability user or service account, although the typical host scenario requires CAP_NET_ADMIN or administrator control. The issue is not directly network reachable because the attacker must trigger interface down, XDP detach, or ring resize operations. Impact is denial of service through resource exhaustion only, with no supported evidence of memory corruption, information disclosure, or privilege escalation.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate / Low-like (with actual score 1)	YES	REMOTE INIT LEAK NETWORK SKB HARDWARE LINUS MEMORY  DECREASED_TO_MODERATE_REGULAR_FROM_MODERATE7_BASED_ON_GUESSCVSS_AND_CIANNH DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_ACTIONABLESCORELESSTHAN3	NO	NO	checked

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ACTIONABLESCORE ANALYSIS
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ActionableScore=2
ActionableScoreLower=0

## 1. ActionableScore

* Conservative score: 0
* Paranoid score: 2
* Final recommended bucket: **Ordinary Moderate / Low-like**::

## 2. Signal breakdown

Conservative signals:

* Availability impact realistic: +1. Repeated interface teardown under TX or XDP_TX load can leak skb or xdp_frame references and eventually contribute to resource exhaustion.
* Requires admin/root/CAP_NET_ADMIN in typical deployments: -2. Reliable triggering requires interface down, XDP detach, ring resize, or similar network device management operations.
* Rare AND difficult-to-reach subsystem/configuration: -1. The issue is specific to the Aquantia Atlantic driver and requires the affected hardware or driver path.

Conservative total is capped at 0 after negative adjustment.

Paranoid signals:

* Local reduced-privilege trigger: +1. In environments where network administration or XDP control is delegated to a service account, container root, or reduced-capability operator, the trigger may be below full host-root.
* Reliable resource-exhaustion DoS concern: +1. The leak is persistent across teardown and can keep page_pool inflight references alive, causing repeated stalled shutdown warnings and accumulated resource loss.
* Availability impact realistic: +1. Sustained repeated teardown cycles can cause persistent memory and page_pool resource leakage beyond a single transient warning.
* Rare AND difficult-to-reach subsystem/configuration: -1. The affected path is driver and hardware specific.

Paranoid total: 2.

No memory corruption signal is awarded. The patch releases lost references and DMA mappings during teardown, but does not show UAF, double-free, OOB write, attacker-controlled overwrite, type confusion, or page-cache corruption.

## 3. Reachability analysis

The bug is not remotely network-triggerable by packet traffic alone. Remote traffic may help create TX or XDP_TX load, but the vulnerable condition is reached when the local system performs interface teardown, XDP detach, ring resize, or similar driver management operations.

In typical deployments, those operations require administrator privileges or CAP_NET_ADMIN. Namespace or container delegation can reduce the practical privilege requirement if an untrusted actor is allowed to manage the affected netdev or XDP configuration, but that is not the default assumption.

The path is not broadly default-exposed. It depends on Aquantia Atlantic hardware or driver use and on teardown occurring under TX or XDP_TX load.

## 4. Severity interpretation

This behaves like a resource leak and DoS-only issue, not an Important-class kernel memory corruption bug. The realistic impact is memory or page_pool resource leakage after repeated teardown operations. There is no supported privilege escalation, confidentiality impact, integrity impact, UAF reclaim primitive, arbitrary write, or cross-boundary ownership violation.

The paranoid interpretation keeps it above purely cosmetic severity because page_pool references can remain inflight indefinitely and warnings can repeat on later teardown operations, but it still remains below Actionable Moderate.

## 5. One-sentence report phrase

The atlantic driver can leak stranded TX skb or xdp_frame references during ring teardown under TX or XDP_TX load, causing persistent resource leakage and possible DoS, but triggering typically requires local network device management privileges and no memory corruption or privilege escalation primitive is evident.

## 6. Manual review recommendation

NO MANUAL CHECK NEEDED

This is a driver-specific resource leak requiring privileged or delegated netdev management operations, with no evidence of memory corruption, information disclosure, integrity impact, or privilege escalation.

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

Patch: net: atlantic: free stranded TX buffers on ring deinit
Commit: 307d80193b4a4a75b8dc4e0d3162be3755abbed7
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=307d80193b4a4a75b8dc4e0d3162be3755abbed7

Commit description:

aq_vec_deinit() drains the TX rings with a single aq_ring_tx_clean()
call, which frees at most AQ_CFG_TX_CLEAN_BUDGET (256) descriptors and
stops at hw_head, which no longer moves once aq_vec_stop() has stopped
the hardware and NAPI. Completed descriptors beyond the budget and
everything still posted in [hw_head, sw_tail) keep their skb or
xdp_frame when the interface goes down: aq_vec_ring_free() then frees
the buffer ring and the references are lost for good.

Today this is a silent memory leak on every interface down under
TX/XDP_TX load. With the conversion of the RX path to page_pool posted
for net-next it becomes much more visible: XDP_TX frames carry fragment
references on the RX ring's page_pool, so a single stranded frame keeps
the pool's inflight count above zero forever. page_pool_destroy() then
never completes, the pool is leaked together with its pages, and
"page_pool_release_retry() stalled pool shutdown" is warned every 60
seconds from that point on, on every ifdown, XDP detach or ring resize
under XDP_TX load.

Bring back aq_ring_tx_deinit() as it was before the removal and use it
for teardown again, with one extension: TX rings can hold xdp_frames
nowadays, so release those too. They are returned with
xdp_return_frame() since this runs in process context.

Fixes: eb36bed ("net: aquantia: remove function aq_ring_tx_deinit")
Cc: stable@vger.kernel.org # v4.11+
Reviewed-by: Sukhdeep Singh <sukhdeeps@marvell.com>
Signed-off-by: Yangyu Chen <cyy@cyyself.name>
Acked-by: Mina Almasry <almasrymina@google.com>
Link: https://patch.msgid.link/tencent_EEDC35FAF2750A3A6A0B39BAE0E2C484860A@qq.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Changed files:
  drivers/net/ethernet/aquantia/atlantic/aq_ring.c
  drivers/net/ethernet/aquantia/atlantic/aq_ring.h
  drivers/net/ethernet/aquantia/atlantic/aq_vec.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=307d80193b4a4a75b8dc4e0d3162be3755abbed7

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

The original Linux kernel CVE announcement for CVE-2026-74623 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-74623

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:H
  The Best / paranoid CVSS score: 5.5

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: 2

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).