ghsa-x689-8m9r-8332
Vulnerability from github
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:
- Those who call dsa_switch_suspend() and dsa_switch_resume() from their device PM ops: qca8k-8xxx, bcm_sf2, microchip ksz
- 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---
{
"affected": [],
"aliases": [
"CVE-2025-37945"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2025-05-20T16:15:32Z",
"severity": null
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: phy: allow MDIO bus PM ops to start/stop state machine for phylink-controlled PHY\n\nDSA has 2 kinds of drivers:\n\n1. Those who call dsa_switch_suspend() and dsa_switch_resume() from\n their device PM ops: qca8k-8xxx, bcm_sf2, microchip ksz\n2. Those who don\u0027t: all others. The above methods should be optional.\n\nFor type 1, dsa_switch_suspend() calls dsa_user_suspend() -\u003e phylink_stop(),\nand dsa_switch_resume() calls dsa_user_resume() -\u003e phylink_start().\nThese seem good candidates for setting mac_managed_pm = true because\nthat is essentially its definition [1], but that does not seem to be the\nbiggest problem for now, and is not what this change focuses on.\n\nTalking strictly about the 2nd category of DSA drivers here (which\ndo not have MAC managed PM, meaning that for their attached PHYs,\nmdio_bus_phy_suspend() and mdio_bus_phy_resume() should run in full),\nI have noticed that the following warning from mdio_bus_phy_resume() is\ntriggered:\n\n\tWARN_ON(phydev-\u003estate != PHY_HALTED \u0026\u0026 phydev-\u003estate != PHY_READY \u0026\u0026\n\t\tphydev-\u003estate != PHY_UP);\n\nbecause the PHY state machine is running.\n\nIt\u0027s running as a result of a previous dsa_user_open() -\u003e ... -\u003e\nphylink_start() -\u003e phy_start() having been initiated by the user.\n\nThe previous mdio_bus_phy_suspend() was supposed to have called\nphy_stop_machine(), but it didn\u0027t. So this is why the PHY is in state\nPHY_NOLINK by the time mdio_bus_phy_resume() runs.\n\nmdio_bus_phy_suspend() did not call phy_stop_machine() because for\nphylink, the phydev-\u003eadjust_link function pointer is NULL. This seems a\ntechnicality introduced by commit fddd91016d16 (\"phylib: fix PAL state\nmachine restart on resume\"). That commit was written before phylink\nexisted, and was intended to avoid crashing with consumer drivers which\ndon\u0027t use the PHY state machine - phylink always does, when using a PHY.\nBut phylink itself has historically not been developed with\nsuspend/resume in mind, and apparently not tested too much in that\nscenario, allowing this bug to exist unnoticed for so long. Plus, prior\nto the WARN_ON(), it would have likely been invisible.\n\nThis issue is not in fact restricted to type 2 DSA drivers (according to\nthe above ad-hoc classification), but can be extrapolated to any MAC\ndriver with phylink and MDIO-bus-managed PHY PM ops. DSA is just where\nthe issue was reported. Assuming mac_managed_pm is set correctly, a\nquick search indicates the following other drivers might be affected:\n\n$ grep -Zlr PHYLINK_NETDEV drivers/ | xargs -0 grep -L mac_managed_pm\ndrivers/net/ethernet/atheros/ag71xx.c\ndrivers/net/ethernet/microchip/sparx5/sparx5_main.c\ndrivers/net/ethernet/microchip/lan966x/lan966x_main.c\ndrivers/net/ethernet/freescale/dpaa2/dpaa2-mac.c\ndrivers/net/ethernet/freescale/fs_enet/fs_enet-main.c\ndrivers/net/ethernet/freescale/dpaa/dpaa_eth.c\ndrivers/net/ethernet/freescale/ucc_geth.c\ndrivers/net/ethernet/freescale/enetc/enetc_pf_common.c\ndrivers/net/ethernet/marvell/mvpp2/mvpp2_main.c\ndrivers/net/ethernet/marvell/mvneta.c\ndrivers/net/ethernet/marvell/prestera/prestera_main.c\ndrivers/net/ethernet/mediatek/mtk_eth_soc.c\ndrivers/net/ethernet/altera/altera_tse_main.c\ndrivers/net/ethernet/wangxun/txgbe/txgbe_phy.c\ndrivers/net/ethernet/meta/fbnic/fbnic_phylink.c\ndrivers/net/ethernet/tehuti/tn40_phy.c\ndrivers/net/ethernet/mscc/ocelot_net.c\n\nMake the existing conditions dependent on the PHY device having a\nphydev-\u003ephy_link_change() implementation equal to the default\nphy_link_change() provided by phylib. Otherwise, we implicitly know that\nthe phydev has the phylink-provided phylink_phy_change() callback, and\nwhen phylink is used, the PHY state machine always needs to be stopped/\nstarted on the suspend/resume path. The code is structured as such that\nif phydev-\u003ephy_link_change() is absent, it is a matter of time until the\nkernel will crash - no need to further complicate the test.\n\nThus, for the situation where the PM is not managed b\n---truncated---",
"id": "GHSA-x689-8m9r-8332",
"modified": "2025-05-20T18:30:56Z",
"published": "2025-05-20T18:30:56Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2025-37945"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/54e5d00a8de6c13f6c01a94ed48025e882cd15f7"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/a6ed6f8ec81b8ca7100dcd9e62bdbc0dff1b2259"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/bd4037d51d3f6667636a1383e78e48a5b7b60755"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/fc75ea20ffb452652f0d4033f38fe88d7cfdae35"
}
],
"schema_version": "1.4.0",
"severity": []
}
Sightings
| Author | Source | Type | Date |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
- Confirmed: The vulnerability is confirmed from an analyst perspective.
- Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
- Patched: This vulnerability was successfully patched by the user reporting the sighting.
- Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
- Not confirmed: The user expresses doubt about the veracity of the vulnerability.
- Not patched: This vulnerability was not successfully patched by the user reporting the sighting.