[CVE-2026-98594][MODERATE REGULAR] tg3: clean up PHYLIB resources on probe failure [ Upstream

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

CVE: CVE-2026-98594
Priority: MODERATE REGULAR
AL-KERNEL base severity: MODERATE
KPANIC flag: NO
Patch: tg3: clean up PHYLIB resources on probe failure [ Upstream
Commit: ce86d6929d03e6b0abcb781dfa50f9f0816bff78
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=ce86d6929d03e6b0abcb781dfa50f9f0816bff78
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98594
Analysis date: Sat, 24 Oct 2026 13:07:28 -0400
ActionableScore: 2
ActionableScore lower bound: 1
Actionable bucket: Ordinary Moderate
Manual review required: NO

Summary:
A late tg3 probe failure leaks active PHYLIB resources after owner teardown, creating inconsistent lifetime state but no demonstrated stale use or memory corruption.

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

The original Linux kernel CVE announcement for CVE-2026-98594 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98594

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: MODERATE REGULAR
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-2026-98594	MODERATE	https://www.kernelcve.org/list/?q=CVE-2026-98594 CHECK WITH IMPACT FROM ORIG NN MODERATE | AEGIS IMPACT MODERATE AEGIS_AS=0 LEGACY=MODERATE RESULT=SAME (final reconciliation agrees; DECISION: both 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:L/I:L/A:H';CWE-404;CWE-459;*CWE-772;Other CVSS 'AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '5.8';DESCR 'A late failure in tg3_init_one can leave the MDIO bus registered and the PHY connected after mappings and the netdev are released. The demonstrated primitive is incomplete resource cleanup during device probe, with a persistent resource leak and inconsistent driver state. A possible use after free remains because PHYLIB objects or MDIO callbacks may retain references to the released tg3 private state, but no reachable stale dereference or controlled memory access is established by the available code. For the CVSS the PR:L value reflects that reliable triggering normally requires a local user or process able to influence driver probing, device binding, fault injection, or controlled hardware state. The issue is not remotely reachable through ordinary network traffic and attack complexity is high because initialization must fail after PHYLIB setup has partially completed. Automated impact decision path. The original SimpleNet classifier selected MODERATE_KPANIC. The primary LLM estimated paranoid CVSS 5.8 and the production ActionableScore returned 2 with recommendation Ordinary Moderate. The production rules then evaluated CVSS thresholds and ActionableScore thresholds. Recorded rule transitions were ActionableScore thresholds stage MODERATE_KPANIC to MODERATE because the ActionableScore threshold 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 DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN4. The independent weaker Aegis shadow evaluated CVSS 0.0 and ActionableScore 0 with primitive class CLASS_C and manual review REQUIRED. Its independently reconciled impact was MODERATE. The shadow agreed with the final production impact and aggregation did not change that impact. The final reported impact is MODERATE.';YES REQUIRES MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate (with actual score 2)	MAYBE	REMOTE SIMPLEFIX ERRORPATH NETWORK HARDWARE TEST  DECREASED_TO_MODERATEREG_BASED_ON_ACTIONABLESCORELESSTHAN4	-	-	checked

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

ActionableScore=2
ActionableScoreLower=1
PrimitiveClass=CLASS_B
RealUAF=NO
HostAdminRequired=UNKNOWN
NamespaceScopedPrivilege=NO
ImportantCandidate=NO
ManualReview=RECOMMENDED
AutoDowngradeAllowed=YES
RequiresHostUID0=UNKNOWN
AuthorizationDecisionBypass=NO
ProtectedResourceImpact=NONE
B4PendingReview=NO
B4PendingConfirmed=NO

1. ActionableScore

* Raw base score: 1.
* Conservative score: 1; no floor or cap applies.
* Raw paranoid score: 2.
* Paranoid score: 2; no floor or cap applies.
* Final recommended bucket: **Ordinary Moderate**::

2. Signal breakdown

* +1 concrete persistent resource/reference leak: `tg3_get_invariants()` may register the MDIO bus and connect the PHY, but the failure path previously released mappings and the netdev without unregistering or disconnecting them.
* Paranoid +1 weak indirect lifetime/ownership candidate: registered PHYLIB objects remain active after teardown of their owning driver state, making a later stale callback/reference technically plausible.
* No UAF score: no post-free callback, dereference, mutation, or other stale use is shown.
* No crash/DoS point: neither the patch nor supplied evidence establishes a kernel fault.
* No privilege penalty: effective trigger privilege is unresolved, so host-admin privilege is not assumed.
* No B5-R, B3-PENDING, or B4-PENDING signal: there is no OOB write, shared-backing write, or authorization decision bypass.

3. Reachability analysis

Triggering requires a late `tg3_init_one()` probe failure after PHYLIB initialization. Ordinary network packets do not reach this path. The evidence does not establish whether an attacker can induce the needed probe failure through device binding, fault injection, or hardware behavior, nor whether host-administrator powers are required. PCI probe control is not a namespace-scoped operation, and no namespace-only complete trigger exists in the supplied evidence. No rare-hardware penalty is applied merely because this is a NIC driver.

4. Primitive and severity reading

The proven primitive is incomplete teardown leaving an MDIO bus registered and a PHY connected after associated mappings/netdev state are released. This is an escaping resource and ownership-lifetime mismatch, hence constrained CLASS_B, but not a demonstrated UAF. A later PHYLIB callback into freed `tg3` state is speculative because no consumer or stale dereference is supplied. ImportantCandidate is therefore NO, and auto-downgrade remains allowed, while manual source review is advisable to verify callback and registration lifetimes.

5. One-sentence report phrase

A late tg3 probe failure leaks active PHYLIB resources after owner teardown, creating inconsistent lifetime state but no demonstrated stale use or memory corruption.

6. Manual review advice

MANUAL CHECK RECOMMENDED

Review PHYLIB callback ownership and whether the surviving registration can access released `tg3` private state.

7. Call-site confidence

Call-site confidence: medium

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

Patch: tg3: clean up PHYLIB resources on probe failure [ Upstream
Commit: ce86d6929d03e6b0abcb781dfa50f9f0816bff78
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=ce86d6929d03e6b0abcb781dfa50f9f0816bff78

Changed files:
  drivers/net/ethernet/broadcom/tg3.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=ce86d6929d03e6b0abcb781dfa50f9f0816bff78

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

The original Linux kernel CVE announcement for CVE-2026-98594 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-98594

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:L/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:L/I:L/A:H
  The Best / paranoid CVSS score: 5.8

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: MODERATE
KPANIC detected for this report: NO
Published priority for this report (same as in Subject): MODERATE REGULAR

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).