In the Linux kernel, the following vulnerability has been resolved:

net: phy: allow MDIO bus PM ops to start/stop state machine for phylink-controlled PHY

DSA has 2 kinds of drivers:

1. Those who call dsa_switch_suspend() and dsa_switch_resume() from
their device PM ops: qca8k-8xxx, bcm_sf2, microchip ksz
2. Those who don't: all others. The above methods should be optional.

For type 1, dsa_switch_suspend() calls dsa_user_suspend() -> phylink_stop(),
and dsa_switch_resume() calls dsa_user_resume() -> phylink_start().
These seem good candidates for setting mac_managed_pm = true because
that is essentially its definition [1], but that does not seem to be the
biggest problem for now, and is not what this change focuses on.

Talking strictly about the 2nd category of DSA drivers here (which
do not have MAC managed PM, meaning that for their attached PHYs,
mdio_bus_phy_suspend() and mdio_bus_phy_resume() should run in full),
I have noticed that the following warning from mdio_bus_phy_resume() is
triggered:

WARN_ON(phydev->state != PHY_HALTED && phydev->state != PHY_READY &&
phydev->state != PHY_UP);

because the PHY state machine is running.

It's running as a result of a previous dsa_user_open() -> ... ->
phylink_start() -> phy_start() having been initiated by the user.

The previous mdio_bus_phy_suspend() was supposed to have called
phy_stop_machine(), but it didn't. So this is why the PHY is in state
PHY_NOLINK by the time mdio_bus_phy_resume() runs.

mdio_bus_phy_suspend() did not call phy_stop_machine() because for
phylink, the phydev->adjust_link function pointer is NULL. This seems a
technicality introduced by commit fddd91016d16 ("phylib: fix PAL state
machine restart on resume"). That commit was written before phylink
existed, and was intended to avoid crashing with consumer drivers which
don't use the PHY state machine - phylink always does, when using a PHY.
But phylink itself has historically not been developed with
suspend/resume in mind, and apparently not tested too much in that
scenario, allowing this bug to exist unnoticed for so long. Plus, prior
to the WARN_ON(), it would have likely been invisible.

This issue is not in fact restricted to type 2 DSA drivers (according to
the above ad-hoc classification), but can be extrapolated to any MAC
driver with phylink and MDIO-bus-managed PHY PM ops. DSA is just where
the issue was reported. Assuming mac_managed_pm is set correctly, a
quick search indicates the following other drivers might be affected:

$ grep -Zlr PHYLINK_NETDEV drivers/ | xargs -0 grep -L mac_managed_pm
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

Make the existing conditions dependent on the PHY device having a
phydev->phy_link_change() implementation equal to the default
phy_link_change() provided by phylib. Otherwise, we implicitly know that
the phydev has the phylink-provided phylink_phy_change() callback, and
when phylink is used, the PHY state machine always needs to be stopped/
started on the suspend/resume path. The code is structured as such that
if phydev->phy_link_change() is absent, it is a matter of time until the
kernel will crash - no need to further complicate the test.

Thus, for the situation where the PM is not managed b
---truncated---

Metrics

No CVSS v4.0

Attack Vector Local

Attack Complexity Low

Privileges Required Low

Scope Unchanged

Confidentiality Impact None

Integrity Impact None

Availability Impact High

User Interaction None

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

The EPSS score is 0.00028.

Key SSVC decision points have not yet been added.

Affected Vendors & Products

Vendors Products
Linux
  • Linux Kernel

Configuration 1 [-]

OR cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:6.15:rc1:*:*:*:*:*:*

No data.

No data.

Advisories
Source ID Title
EUVD EUVD EUVD-2025-15839 In the Linux kernel, the following vulnerability has been resolved: net: phy: allow MDIO bus PM ops to start/stop state machine for phylink-controlled PHY DSA has 2 kinds of drivers: 1. Those who call dsa_switch_suspend() and dsa_switch_resume() from their device PM ops: qca8k-8xxx, bcm_sf2, microchip ksz 2. Those who don't: all others. The above methods should be optional. For type 1, dsa_switch_suspend() calls dsa_user_suspend() -> phylink_stop(), and dsa_switch_resume() calls dsa_user_resume() -> phylink_start(). These seem good candidates for setting mac_managed_pm = true because that is essentially its definition [1], but that does not seem to be the biggest problem for now, and is not what this change focuses on. Talking strictly about the 2nd category of DSA drivers here (which do not have MAC managed PM, meaning that for their attached PHYs, mdio_bus_phy_suspend() and mdio_bus_phy_resume() should run in full), I have noticed that the following warning from mdio_bus_phy_resume() is triggered: WARN_ON(phydev->state != PHY_HALTED && phydev->state != PHY_READY && phydev->state != PHY_UP); because the PHY state machine is running. It's running as a result of a previous dsa_user_open() -> ... -> phylink_start() -> phy_start() having been initiated by the user. The previous mdio_bus_phy_suspend() was supposed to have called phy_stop_machine(), but it didn't. So this is why the PHY is in state PHY_NOLINK by the time mdio_bus_phy_resume() runs. mdio_bus_phy_suspend() did not call phy_stop_machine() because for phylink, the phydev->adjust_link function pointer is NULL. This seems a technicality introduced by commit fddd91016d16 ("phylib: fix PAL state machine restart on resume"). That commit was written before phylink existed, and was intended to avoid crashing with consumer drivers which don't use the PHY state machine - phylink always does, when using a PHY. But phylink itself has historically not been developed with suspend/resume in mind, and apparently not tested too much in that scenario, allowing this bug to exist unnoticed for so long. Plus, prior to the WARN_ON(), it would have likely been invisible. This issue is not in fact restricted to type 2 DSA drivers (according to the above ad-hoc classification), but can be extrapolated to any MAC driver with phylink and MDIO-bus-managed PHY PM ops. DSA is just where the issue was reported. Assuming mac_managed_pm is set correctly, a quick search indicates the following other drivers might be affected: $ grep -Zlr PHYLINK_NETDEV drivers/ | xargs -0 grep -L mac_managed_pm 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 Make the existing conditions dependent on the PHY device having a phydev->phy_link_change() implementation equal to the default phy_link_change() provided by phylib. Otherwise, we implicitly know that the phydev has the phylink-provided phylink_phy_change() callback, and when phylink is used, the PHY state machine always needs to be stopped/ started on the suspend/resume path. The code is structured as such that if phydev->phy_link_change() is absent, it is a matter of time until the kernel will crash - no need to further complicate the test. Thus, for the situation where the PM is not managed b ---truncated---
Ubuntu USN Ubuntu USN USN-7594-1 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-7594-2 Linux kernel (Azure) vulnerabilities
Ubuntu USN Ubuntu USN USN-7594-3 Linux kernel vulnerabilities
Fixes

Solution

No solution given by the vendor.

Workaround

No workaround given by the vendor.

References
Link Providers
https://git.kernel.org/stable/c/54e5d00a8de6c13f6c01a94ed48025e882cd15f7 cve-icon cve-icon
https://git.kernel.org/stable/c/a6ed6f8ec81b8ca7100dcd9e62bdbc0dff1b2259 cve-icon cve-icon
https://git.kernel.org/stable/c/bd4037d51d3f6667636a1383e78e48a5b7b60755 cve-icon cve-icon
https://git.kernel.org/stable/c/fc75ea20ffb452652f0d4033f38fe88d7cfdae35 cve-icon cve-icon
https://lore.kernel.org/linux-cve-announce/2025052044-CVE-2025-37945-7849@gregkh/T cve-icon
https://nvd.nist.gov/vuln/detail/CVE-2025-37945 cve-icon
https://www.cve.org/CVERecord?id=CVE-2025-37945 cve-icon
History

Mon, 17 Nov 2025 13:00:00 +0000

Type Values Removed Values Added
First Time appeared Linux
Linux linux Kernel
Weaknesses CWE-476
CPEs cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:6.15:rc1:*:*:*:*:*:*
Vendors & Products Linux
Linux linux Kernel
Metrics cvssV3_1

{'score': 2.5, 'vector': 'CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:L'}

 cvssV3_1

{'score': 5.5, 'vector': 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H'}

Fri, 04 Jul 2025 15:00:00 +0000

Type Values Removed Values Added
Metrics cvssV3_1

{'score': 7.0, 'vector': 'CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H'}

threat_severity

Moderate

 cvssV3_1

{'score': 2.5, 'vector': 'CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:L'}

threat_severity

Low

Fri, 06 Jun 2025 22:00:00 +0000

Type Values Removed Values Added
Metrics cvssV3_1

{'score': 5.5, 'vector': 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H'}

 cvssV3_1

{'score': 7.0, 'vector': 'CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H'}

Tue, 27 May 2025 02:45:00 +0000

Type Values Removed Values Added
References
Metrics threat_severity

None

 cvssV3_1

{'score': 5.5, 'vector': 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H'}

threat_severity

Moderate

Tue, 20 May 2025 16:15:00 +0000

Type Values Removed Values Added
Description In the Linux kernel, the following vulnerability has been resolved: net: phy: allow MDIO bus PM ops to start/stop state machine for phylink-controlled PHY DSA has 2 kinds of drivers: 1. Those who call dsa_switch_suspend() and dsa_switch_resume() from their device PM ops: qca8k-8xxx, bcm_sf2, microchip ksz 2. Those who don't: all others. The above methods should be optional. For type 1, dsa_switch_suspend() calls dsa_user_suspend() -> phylink_stop(), and dsa_switch_resume() calls dsa_user_resume() -> phylink_start(). These seem good candidates for setting mac_managed_pm = true because that is essentially its definition [1], but that does not seem to be the biggest problem for now, and is not what this change focuses on. Talking strictly about the 2nd category of DSA drivers here (which do not have MAC managed PM, meaning that for their attached PHYs, mdio_bus_phy_suspend() and mdio_bus_phy_resume() should run in full), I have noticed that the following warning from mdio_bus_phy_resume() is triggered: WARN_ON(phydev->state != PHY_HALTED && phydev->state != PHY_READY && phydev->state != PHY_UP); because the PHY state machine is running. It's running as a result of a previous dsa_user_open() -> ... -> phylink_start() -> phy_start() having been initiated by the user. The previous mdio_bus_phy_suspend() was supposed to have called phy_stop_machine(), but it didn't. So this is why the PHY is in state PHY_NOLINK by the time mdio_bus_phy_resume() runs. mdio_bus_phy_suspend() did not call phy_stop_machine() because for phylink, the phydev->adjust_link function pointer is NULL. This seems a technicality introduced by commit fddd91016d16 ("phylib: fix PAL state machine restart on resume"). That commit was written before phylink existed, and was intended to avoid crashing with consumer drivers which don't use the PHY state machine - phylink always does, when using a PHY. But phylink itself has historically not been developed with suspend/resume in mind, and apparently not tested too much in that scenario, allowing this bug to exist unnoticed for so long. Plus, prior to the WARN_ON(), it would have likely been invisible. This issue is not in fact restricted to type 2 DSA drivers (according to the above ad-hoc classification), but can be extrapolated to any MAC driver with phylink and MDIO-bus-managed PHY PM ops. DSA is just where the issue was reported. Assuming mac_managed_pm is set correctly, a quick search indicates the following other drivers might be affected: $ grep -Zlr PHYLINK_NETDEV drivers/ | xargs -0 grep -L mac_managed_pm 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 Make the existing conditions dependent on the PHY device having a phydev->phy_link_change() implementation equal to the default phy_link_change() provided by phylib. Otherwise, we implicitly know that the phydev has the phylink-provided phylink_phy_change() callback, and when phylink is used, the PHY state machine always needs to be stopped/ started on the suspend/resume path. The code is structured as such that if phydev->phy_link_change() is absent, it is a matter of time until the kernel will crash - no need to further complicate the test. Thus, for the situation where the PM is not managed b ---truncated---
Title net: phy: allow MDIO bus PM ops to start/stop state machine for phylink-controlled PHY
References
cve-icon MITRE

Status: PUBLISHED

Assigner: Linux

Published:

Updated: 2025-05-26T05:24:16.339Z

Reserved: 2025-04-16T04:51:23.972Z

Link: CVE-2025-37945

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Analyzed

Published: 2025-05-20T16:15:32.453

Modified: 2025-11-17T12:57:32.553

Link: CVE-2025-37945

cve-icon Redhat

Severity : Low

Publid Date: 2025-05-20T00:00:00Z

Links: CVE-2025-37945 - Bugzilla

cve-icon OpenCVE Enrichment

No data.