[CVE-2026-98967][LOW] cxgb4/ch_ktls: disable softirqs around tid_list erases [ Upstream

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

CVE: CVE-2026-98967
Priority: LOW
AL-KERNEL base severity: LOW
KPANIC flag: NO
Patch: cxgb4/ch_ktls: disable softirqs around tid_list erases [ Upstream
Commit: 8739f06e3f82cd715f7dd10ab24029ed881efc90
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=8739f06e3f82cd715f7dd10ab24029ed881efc90
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98967
Analysis date: Mon, 26 Oct 2026 19:26:31 -0400
ActionableScore: 0
ActionableScore lower bound: unknown
Actionable bucket: Ordinary Moderate
Manual review required: NO

Summary:
A same-CPU receive softirq can deadlock against kTLS cleanup holding the shared XArray lock, causing a soft lockup and possible watchdog panic.

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

The original Linux kernel CVE announcement for CVE-2026-98967 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98967

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-2026-98967	LOW	https://www.kernelcve.org/list/?q=CVE-2026-98967 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:H/PR:L/UI:N/S:U/C:N/I:N/A:H';CWE-667;*CWE-833;CWE-362;BEST CVSS score: '4.7';DESCR 'The cxgb4 kTLS tid_list is shared between cleanup code and the receive softirq path. Cleanup used xa_erase while softirqs remained enabled, so a receive softirq on the same CPU could interrupt an erase that held the XArray lock and then spin in xa_insert_bh on that same lock. This creates a synchronization deadlock that can cause a CPU soft lockup and potentially a kernel panic through watchdog policy. For the CVSS the PR:L value reflects that a local process with access to a kTLS socket may reach the device add error cleanup path, while device removal normally requires administrative control. AC:H is required because exploitation depends on supported Chelsio hardware, active kTLS offload, a cleanup operation, and a receive softirq hitting the narrow same CPU timing window. The demonstrated primitive is deadlock only, with no evidence of UAF, OOB access, information disclosure, or memory corruption. Automated impact decision path. The original SimpleNet classifier selected IMPORTANT. The primary LLM estimated paranoid CVSS 4.7 and the production ActionableScore returned 0 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 2.7 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 0)	MAYBE	REMOTE SIMPLEFIX ERRORPATH NETWORK HARDWARE 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=0
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: 0 (+1 deadlock/strong DoS, -1 narrow same-CPU softirq timing).
* Conservative score: 0; no floor or cap applied.
* Raw paranoid score: 0.
* Paranoid score: 0; no technically supported additional primitive.
* Final recommended bucket: **Ordinary Moderate**::

2. Signal breakdown

* +1 Reliable kernel crash/strong DoS: `xa_erase()` can hold the XArray lock while an interrupting receive softirq spins in `xa_insert_bh()`, causing a CPU soft lockup and possible watchdog panic.
* -1 Hard timing: exploitation requires cleanup to be interrupted on the same CPU by the relevant receive softirq while the lock is held.
* No separate availability point: soft lockup and possible watchdog panic are the same failure path.
* No rare-hardware penalty: Chelsio hardware and active kTLS offload restrict exposure, but the evidence does not establish physical attacker access or a sufficiently rare, unreachable configuration.
* No UAF, OOB access, memory corruption, authorization bypass, disclosure, or integrity primitive is shown.
* B5-R and B3-PENDING do not apply: there is no write outside an allocation or shared-backing write.

3. Reachability analysis

The device-removal path normally implies administrative device management, while the add error path may be reachable through kTLS socket setup. The supplied patch does not establish the complete credentials, capability namespace, or whether an ordinary/delegated user can reliably force that error path. Therefore host-admin and namespace-scoped reachability remain unknown. Supported Chelsio hardware and active offload are prerequisites. The interrupt window is narrow and timing-dependent.

4. Primitive and severity reading

The exact primitive is lock recursion by softirq interruption: process-context cleanup holds an XArray lock without disabling bottom halves, and the receive softirq spins acquiring the same lock. This is CLASS_C availability behavior, not stale-object use or kernel-memory corruption. The patch-supported effect is a CPU soft lockup with possible watchdog escalation; non-crash exploitation leverage is not shown. Important-candidate retention is unwarranted, and automatic downgrade is allowed.

5. One-sentence report phrase

A same-CPU receive softirq can deadlock against kTLS cleanup holding the shared XArray lock, causing a soft lockup and possible watchdog panic.

6. Manual review advice

NO MANUAL CHECK NEEDED

The patch shows a constrained synchronization deadlock without a corruption, lifetime, authorization, or trust-boundary primitive.

7. Call-site confidence

Call-site confidence: high

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

Patch: cxgb4/ch_ktls: disable softirqs around tid_list erases [ Upstream
Commit: 8739f06e3f82cd715f7dd10ab24029ed881efc90
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=8739f06e3f82cd715f7dd10ab24029ed881efc90

Changed files:
  drivers/net/ethernet/chelsio/inline_crypto/ch_ktls/chcr_ktls.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=8739f06e3f82cd715f7dd10ab24029ed881efc90

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

The original Linux kernel CVE announcement for CVE-2026-98967 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98967

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: Not available
  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: unknown
  Paranoid ActionableScore: 0

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).