[CVE-2026-74745][LOW] eth: bnxt: avoid deadlock when canceling IRQ affinity notifier [ Upstream

[CVE-2026-74745][LOW] eth: bnxt: avoid deadlock when canceling IRQ affinity notifier [ Upstream

[AL-KERNEL]

CVE: CVE-2026-74745
Priority: LOW
AL-KERNEL base severity: LOW
KPANIC flag: NO
Patch: eth: bnxt: avoid deadlock when canceling IRQ affinity notifier [ Upstream
Commit: 8b1118fc5a5d2cdc21cc07b5106921ad4f77c544
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=8b1118fc5a5d2cdc21cc07b5106921ad4f77c544
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-74745
Analysis date: Wed, 26 Aug 2026 12:47:19 -0400
ActionableScore: 2
ActionableScore lower bound: 1
Actionable bucket: Ordinary Moderate / Low-like. Not an Important candidate
Manual review required: NO

Summary:
The bnxt driver may deadlock during IRQ affinity notifier cancellation because the notifier callback can take the same netdev lock while unregister waits synchronously, causing a local DoS of reset or teardown paths on affected Broadcom hardware.

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

The original Linux kernel CVE announcement for CVE-2026-74745 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-74745

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-2026-74745	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-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: '4.7';DESCR 'The bnxt driver can deadlock when an IRQ affinity notifier is unregistered while its callback is running because unregistering the notifier waits synchronously and the callback may take the same netdev instance lock to restart an RX queue. This can stall device teardown or reset related paths and cause a denial of service on systems using affected Broadcom bnxt hardware with TPH support. For the CVSS the PR:L is used in the paranoid score because a reduced capability root, service account, or delegated network administrator may be able to trigger device or IRQ affinity operations without full host administrator control. The issue is not directly network reachable and is not triggered by normal packet traffic. Impact is denial of service only through a local driver deadlock, with no evidence of memory corruption, information disclosure, or privilege escalation.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate / Low-like. Not an Important candidate (with actual score 2)  SKIP CVE-2026-74745 UNKNOWN SKIP The Fixes patch not applied yet, so unlikely that actual: url YES  NO NO unknown 	MAYBE	REMOTE DEADLOCK DANGER INIT ERRORPATH NETWORK HARDWARE LINUS  DECREASED_TO_MODERATE_REGULAR_FROM_MODERATE7_BASED_ON_GUESSCVSS_AND_CIANNH DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_ACTIONABLESCORELESSTHAN3	-	-	checked

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

ActionableScore=2
ActionableScoreLower=1

## 1. ActionableScore

* Conservative score: 1
* Paranoid score: 2
* Final recommended bucket: **Ordinary Moderate / Low-like. Not an Important candidate**

## 2. Signal breakdown

* Reliable kernel crash / strong DoS: +1
  The issue can deadlock bnxt device teardown or reset related paths when IRQ affinity notifier unregister waits for a callback that tries to take the same netdev lock.

* Requires admin/root/CAP_NET_ADMIN in typical deployments: -2
  Reliable triggering normally requires privileged control over device teardown, reset, IRQ affinity, driver state, or similar network device management operations.

* Hard or unreliable race / special timing required: -1
  The deadlock depends on overlap between notifier callback execution and synchronous notifier cancellation under the same lock.

* Rare or hardware dependent exposure: -1
  The path is specific to Broadcom bnxt hardware with TPH support and IRQ affinity notifier activity, not a generic networking packet path.

* Paranoid delegated-admin interpretation: +1
  In some environments, a reduced-capability root, service account, or delegated network administrator may control enough device or IRQ-affinity operations to trigger the condition without full host-root equivalence.

No memory corruption, UAF, OOB access, information leak, privilege escalation, page-cache corruption, or remote packet-triggered path is supported by the patch.

## 3. Reachability analysis

The bug is local and device-management oriented. It is not triggered by normal network traffic and is not directly network reachable. The realistic attacker needs control over bnxt device state, IRQ affinity, reset, teardown, or related privileged operations. Namespaces or containers only matter if the environment delegates enough network or device-management capability to a non-host-root actor. The affected path also requires suitable bnxt hardware and TPH-related IRQ affinity notifier behavior.

## 4. Severity interpretation

This behaves like an ordinary Moderate or Low-like availability issue rather than an Important-class vulnerability. The demonstrated consequence is a local driver deadlock causing DoS of device management paths. There is no evidence of memory corruption or a practical privilege escalation primitive. The paranoid score only accounts for delegated administration scenarios, not for stronger impact.

## 5. One-sentence report phrase

The bnxt driver may deadlock during IRQ affinity notifier cancellation because the notifier callback can take the same netdev lock while unregister waits synchronously, causing a local DoS of reset or teardown paths on affected Broadcom hardware.

## 6. Manual review recommendation

NO MANUAL CHECK NEEDED

This can be processed as a non-urgent availability bug unless the product specifically exposes bnxt device reset or IRQ affinity management to reduced-privilege tenants.

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

Patch: eth: bnxt: avoid deadlock when canceling IRQ affinity notifier [ Upstream
Commit: 8b1118fc5a5d2cdc21cc07b5106921ad4f77c544
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=8b1118fc5a5d2cdc21cc07b5106921ad4f77c544

Changed files:
  drivers/net/ethernet/broadcom/bnxt/bnxt.c
  drivers/net/ethernet/broadcom/bnxt/bnxt.h

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=8b1118fc5a5d2cdc21cc07b5106921ad4f77c544

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

The original Linux kernel CVE announcement for CVE-2026-74745 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-74745

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: 1
  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).