[CVE-2026-80715][LOW] igc: remove napi_synchronize() in igc_down() [ Upstream

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

CVE: CVE-2026-80715
Priority: LOW
AL-KERNEL base severity: LOW
KPANIC flag: NO
Patch: igc: remove napi_synchronize() in igc_down() [ Upstream
Commit: ad6e0df267dc96edb7de1fa0a2fb2a70645bff86
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=ad6e0df267dc96edb7de1fa0a2fb2a70645bff86
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80715
Analysis date: Fri, 28 Aug 2026 03:58:45 -0400
ActionableScore: 2
ActionableScore lower bound: 0
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-2026-80715 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80715

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-2026-80715	LOW	CHECK WITH IMPACT FROM ORIG NN MODERATE	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-835;**CWE-400;Other CVSS 'AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:H';BEST CVSS score: '4.7';DESCR 'An igc interface can hang during igc_down after an AF_XDP zero copy application is killed abruptly. The XSK pool may be torn down while NAPI keeps polling, and igc_clean_rx_irq_zc can keep returning the full budget so NAPI_STATE_SCHED is not cleared. A later interface down or reset path may then wait forever in napi_synchronize, leaving the network device unable to shut down cleanly and causing a local denial of service. For the CVSS the PR:L value is used for the paranoid score because a local AF_XDP capable process or delegated service account may be able to create the stuck state, even though full interface administration is commonly restricted. The issue is not network reachable and there is no 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 DANGER SIMPLEFIX NETWORK  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
======================================================================

ActionableScore=2
ActionableScoreLower=0

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

2. Signal breakdown
* Reliable kernel crash / strong DoS: +1. Not a crash, but igc_down can spin forever and leave the interface unable to go down cleanly.
* Availability impact realistic: +1 in paranoid scoring. The impact can persist for the affected interface or reset path, not just a transient warning.
* Local unprivileged trigger: +1 only in paranoid interpretation, where an AF_XDP capable local process or delegated service account can create the stuck state.
* Requires admin/root/CAP_* in typical deployments: -2 for conservative scoring. AF_XDP zero-copy setup and interface reset/down control are usually privileged.
* Rare/configuration-dependent path: -1. Requires Intel igc hardware plus AF_XDP zero-copy usage and abrupt application teardown.
* No memory corruption signal. The patch only changes NAPI shutdown ordering and does not show UAF, OOB, double-free, type confusion, or arbitrary write.

3. Reachability analysis
The bug is local and device/configuration dependent. A realistic trigger requires an igc interface using AF_XDP zero-copy, abrupt teardown of the XSK pool, and a later interface down or reset operation. It is not network-triggerable by packet traffic alone. Namespaces or containers matter only if AF_XDP and network administration are delegated to a less privileged workload, which supports the paranoid PR:L interpretation but not an Important-class score.

4. Severity interpretation
This behaves like ordinary Moderate or Low-like local DoS. The realistic impact is a stuck NAPI/interface shutdown path. There is no supported privilege escalation, confidentiality impact, integrity impact, or memory corruption primitive. Theoretical concern is limited to availability because the patch and call path show synchronization ordering failure, not object lifetime corruption.

5. One-sentence report phrase
An igc interface using AF_XDP zero-copy can hang during igc_down after abrupt XSK pool teardown, causing a local denial of service where the interface or reset path cannot complete cleanly.

6. Manual review recommendation
NO MANUAL CHECK NEEDED
This is a configuration-dependent local availability issue with no memory corruption, no network reachability, and no plausible LPE evidence in the patch context.

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

Patch: igc: remove napi_synchronize() in igc_down() [ Upstream
Commit: ad6e0df267dc96edb7de1fa0a2fb2a70645bff86
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=ad6e0df267dc96edb7de1fa0a2fb2a70645bff86

Changed files:
  drivers/net/ethernet/intel/igc/igc_main.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=ad6e0df267dc96edb7de1fa0a2fb2a70645bff86

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

The original Linux kernel CVE announcement for CVE-2026-80715 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-80715

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: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: 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).