[CVE-2025-37945][LOW] net: phy: allow MDIO bus PM ops to start/stop state machine for phylink-controlled PHY [ Upstream

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

CVE: CVE-2025-37945
Priority: LOW
AL-KERNEL base severity: LOW
KPANIC flag: NO
Patch: net: phy: allow MDIO bus PM ops to start/stop state machine for phylink-controlled PHY [ Upstream
Commit: a6ed6f8ec81b8ca7100dcd9e62bdbc0dff1b2259
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=a6ed6f8ec81b8ca7100dcd9e62bdbc0dff1b2259
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2025-37945
Analysis date: Mon, 12 Oct 2026 20:55:26 -0400
ActionableScore: 2
ActionableScore lower bound: 1
Actionable bucket: Ordinary Moderate
Manual review required: NO

Summary:
No one-sentence report phrase was found.

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

The original Linux kernel CVE announcement for CVE-2025-37945 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2025-37945

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-2025-37945	LOW	https://www.kernelcve.org/list/?q=CVE-2025-37945 CHECK WITH IMPACT FROM ORIG NN MODERATE | AEGIS IMPACT LOW AEGIS_AS=0 LEGACY=LOW RESULT=SAME (legacy and Aegis reconciliation agree; DECISION: both LOW)	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-754;*CWE-664;Other CVSS 'AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '4.7';DESCR 'MDIO bus power management can leave the PHY state machine running during suspend when the PHY is controlled through phylink because adjust_link is NULL in that configuration. The subsequent resume can observe an invalid PHY state and trigger WARN_ON, disrupt the network interface, or in a worst still defensible case contribute to a kernel crash and local denial of service. For the CVSS the PR:L value is used for the paranoid score because some local desktop or appliance policies allow a regular authenticated user to request system suspend without full administrative privileges. Reliable triggering still requires an affected phylink MAC or DSA driver, MDIO bus managed PHY power management, and a suspend and resume cycle. The issue is not directly network reachable because received packets do not invoke the vulnerable power management sequence. No concrete UAF, OOB access, information disclosure, or arbitrary write primitive is present, so confidentiality and integrity remain unaffected.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate (with actual score 2)	MAYBE	DEADLOCK DANGER NETWORK HARDWARE LINUS TEST DECREASED_TO_MODERATE_REGULAR_FROM_MODERATE7_BASED_ON_GUESSCVSS_AND_CIANNH DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_ACTIONABLESCORELESSTHAN3 KPANIC_UNSUPPORTED_REMOVED	-	-	checked

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

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

1. ActionableScore

* Raw conservative score: 1
* Conservative score: 1
* Raw paranoid score: 2
* Paranoid score: 2
* No floor or cap applied.
* Final recommended bucket: **Ordinary Moderate**::

2. Signal breakdown

Conservative signals:

* +1 Broad and realistically exercised subsystem path. The affected MDIO-managed phylink PM pattern exists across multiple DSA and Ethernet drivers and can be reached during normal suspend and resume.
* No negative privilege penalty. The complete trigger may require host administration or may be exposed through local power-management policy, but neither boundary is conclusively established.

Additional paranoid signal:

* +1 Strong DoS concern. The commit explicitly notes that an absent `phy_link_change` callback can eventually crash the kernel, although the directly demonstrated phylink failure is a `WARN_ON` and invalid PHY state rather than a confirmed panic.

Not awarded:

* No UAF, OOB access, overwrite, refcount error, stale lifetime use, or authorization bypass is established.
* No remote-reachability bonus. Network traffic does not invoke the system suspend and resume sequence.
* No local-unprivileged bonus because the complete operation is not proven available to an ordinary user.
* No race penalty because the defect is a deterministic state-machine lifecycle error, not an established narrow timing race.
* No additional availability point because interface disruption and any possible crash are part of the same PM-state failure.
* No confidentiality, integrity, LPE, B5-R, B3-PENDING, or B4-PENDING signal is supported.

3. Reachability analysis

The vulnerable sequence requires an affected phylink-controlled PHY using MDIO-bus-managed power management, prior activation of the PHY state machine, and a system suspend and resume cycle. A remote peer cannot directly invoke this sequence through packets.

System suspend is host-global and is not an operation granted by network or user namespaces, so `NamespaceScopedPrivilege=NO`. Some systems restrict suspend to host administrators, while others delegate it to authenticated desktop or appliance users through power-management policy. The supplied evidence does not establish which model governs the complete trigger, so `HostAdminRequired=UNKNOWN` and `RequiresHostUID0=UNKNOWN`.

Physical PHY hardware and an affected driver are prerequisites, but the listed drivers cover multiple ordinary embedded and Ethernet platforms. This is not sufficient for a rare-hardware penalty. No attacker-controlled race or repeatable memory-placement operation exists.

4. Primitive and severity interpretation

The exact defect is incorrect PHY state-machine lifecycle handling. The old condition uses `adjust_link` to decide whether to stop and restart the state machine, but phylink intentionally leaves `adjust_link` NULL while still using that state machine. Consequently, suspend can leave the machine running and resume can encounter an unexpected state.

This is neither fixed stale storage nor an active structured-object UAF. There is no release followed by a second lifetime or refcount mutation. The demonstrated consequence is `WARN_ON` and inconsistent PHY operation. Device or network-interface disruption is plausible, and a kernel crash is a defensible upper-bound concern only for more invalid callback states described by the commit.

`PrimitiveClass=CLASS_C` because the evidence establishes invalid-state and possible DoS behavior without an independently useful corruption primitive. `ImportantCandidate=NO` and `AutoDowngradeAllowed=YES` because no unresolved memory-corruption, ownership, authorization, or security-boundary primitive remains.

5. One-sentence report phrase

Incorrect MDIO power-management handling can leave a phylink-controlled PHY state machine active across suspend and cause an invalid state warning, interface disruption, or a possible local denial of service during resume.

6. Manual review recommendation

NO MANUAL CHECK NEEDED

The patch addresses PM state-machine coordination without evidence of memory corruption, authorization bypass, remote triggering, or exploitation leverage beyond device disruption and a possible crash.

7. Call-site confidence

Call-site confidence: high

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

Patch: net: phy: allow MDIO bus PM ops to start/stop state machine for phylink-controlled PHY [ Upstream
Commit: a6ed6f8ec81b8ca7100dcd9e62bdbc0dff1b2259
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=a6ed6f8ec81b8ca7100dcd9e62bdbc0dff1b2259

Changed files:
  drivers/net/ethernet/atheros/ag71xx.c
  drivers/net/ethernet/microchip/sparx5/sparx5_main.c
  drivers/net/ethernet/microchip/lan966x/lan966x_main.c
  drivers/net/ethernet/freescale/dpaa2/dpaa2-mac.c
  drivers/net/ethernet/freescale/fs_enet/fs_enet-main.c
  drivers/net/ethernet/freescale/dpaa/dpaa_eth.c
  drivers/net/ethernet/freescale/ucc_geth.c
  drivers/net/ethernet/freescale/enetc/enetc_pf_common.c
  drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c
  drivers/net/ethernet/marvell/mvneta.c
  drivers/net/ethernet/marvell/prestera/prestera_main.c
  drivers/net/ethernet/mediatek/mtk_eth_soc.c
  drivers/net/ethernet/altera/altera_tse_main.c
  drivers/net/ethernet/wangxun/txgbe/txgbe_phy.c
  drivers/net/ethernet/meta/fbnic/fbnic_phylink.c
  drivers/net/ethernet/tehuti/tn40_phy.c
  drivers/net/ethernet/mscc/ocelot_net.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=a6ed6f8ec81b8ca7100dcd9e62bdbc0dff1b2259

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

The original Linux kernel CVE announcement for CVE-2025-37945 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2025-37945

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:L
  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).