CVE-2025-39874
Full vulnerability record from the local CVENow database.
Description
In the Linux kernel, the following vulnerability has been resolved: macsec: sync features on RTM_NEWLINK Syzkaller managed to lock the lower device via ETHTOOL_SFEATURES: netdev_lock include/linux/netdevice.h:2761 [inline] netdev_lock_ops include/net/netdev_lock.h:42 [inline] netdev_sync_lower_features net/core/dev.c:10649 [inline] __netdev_update_features+0xcb1/0x1be0 net/core/dev.c:10819 netdev_update_features+0x6d/0xe0 net/core/dev.c:10876 macsec_notify+0x2f5/0x660 drivers/net/macsec.c:4533 notifier_call_chain+0x1b3/0x3e0 kernel/notifier.c:85 call_netdevice_notifiers_extack net/core/dev.c:2267 [inline] call_netdevice_notifiers net/core/dev.c:2281 [inline] netdev_features_change+0x85/0xc0 net/core/dev.c:1570 __dev_ethtool net/ethtool/ioctl.c:3469 [inline] dev_ethtool+0x1536/0x19b0 net/ethtool/ioctl.c:3502 dev_ioctl+0x392/0x1150 net/core/dev_ioctl.c:759 It happens because lower features are out of sync with the upper: __dev_ethtool (real_dev) netdev_lock_ops(real_dev) ETHTOOL_SFEATURES __netdev_features_change netdev_sync_upper_features disable LRO on the lower if (old_features != dev->features) netdev_features_change fires NETDEV_FEAT_CHANGE macsec_notify NETDEV_FEAT_CHANGE netdev_update_features (for each macsec dev) netdev_sync_lower_features if (upper_features != lower_features) netdev_lock_ops(lower) # lower == real_dev stuck ... netdev_unlock_ops(real_dev) Per commit af5f54b0ef9e ("net: Lock lower level devices when updating features"), we elide the lock/unlock when the upper and lower features are synced. Makes sure the lower (real_dev) has proper features after the macsec link has been created. This makes sure we never hit the situation where we need to sync upper flags to the lower.
Severity
MEDIUM
CVSS score
5.5
(v3.1)
Vulnerability status
Modified
Source identifier
416baaa9-dc9f-4396-8d5f-8c081fb06d67
Published
2025-09-23 06:15:46.813000
Last modified
2026-10-19 21:10:00.160000
View original CVE JSON
{
"id": "CVE-2025-39874",
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"published": "2025-09-23T06:15:46.813",
"lastModified": "2026-10-19T21:10:00.160",
"vulnStatus": "Modified",
"cveTags": [],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nmacsec: sync features on RTM_NEWLINK\n\nSyzkaller managed to lock the lower device via ETHTOOL_SFEATURES:\n\n netdev_lock include/linux/netdevice.h:2761 [inline]\n netdev_lock_ops include/net/netdev_lock.h:42 [inline]\n netdev_sync_lower_features net/core/dev.c:10649 [inline]\n __netdev_update_features+0xcb1/0x1be0 net/core/dev.c:10819\n netdev_update_features+0x6d/0xe0 net/core/dev.c:10876\n macsec_notify+0x2f5/0x660 drivers/net/macsec.c:4533\n notifier_call_chain+0x1b3/0x3e0 kernel/notifier.c:85\n call_netdevice_notifiers_extack net/core/dev.c:2267 [inline]\n call_netdevice_notifiers net/core/dev.c:2281 [inline]\n netdev_features_change+0x85/0xc0 net/core/dev.c:1570\n __dev_ethtool net/ethtool/ioctl.c:3469 [inline]\n dev_ethtool+0x1536/0x19b0 net/ethtool/ioctl.c:3502\n dev_ioctl+0x392/0x1150 net/core/dev_ioctl.c:759\n\nIt happens because lower features are out of sync with the upper:\n\n __dev_ethtool (real_dev)\n netdev_lock_ops(real_dev)\n ETHTOOL_SFEATURES\n __netdev_features_change\n netdev_sync_upper_features\n disable LRO on the lower\n if (old_features != dev->features)\n netdev_features_change\n fires NETDEV_FEAT_CHANGE\n\tmacsec_notify\n\t NETDEV_FEAT_CHANGE\n\t netdev_update_features (for each macsec dev)\n\t netdev_sync_lower_features\n\t if (upper_features != lower_features)\n\t netdev_lock_ops(lower) # lower == real_dev\n\t\t stuck\n\t\t ...\n\n netdev_unlock_ops(real_dev)\n\nPer commit af5f54b0ef9e (\"net: Lock lower level devices when updating\nfeatures\"), we elide the lock/unlock when the upper and lower features\nare synced. Makes sure the lower (real_dev) has proper features after\nthe macsec link has been created. This makes sure we never hit the\nsituation where we need to sync upper flags to the lower."
},
{
"lang": "es",
"value": "En el kernel de Linux, la siguiente vulnerabilidad ha sido resuelta:\n\nmacsec: sincronizar características en RTM_NEWLINK\n\nSyzkaller logró bloquear el dispositivo inferior a través de ETHTOOL_SFEATURES:\n\n netdev_lock include/linux/netdevice.h:2761 [inline]\n netdev_lock_ops include/net/netdev_lock.h:42 [inline]\n netdev_sync_lower_features net/core/dev.c:10649 [inline]\n __netdev_update_features+0xcb1/0x1be0 net/core/dev.c:10819\n netdev_update_features+0x6d/0xe0 net/core/dev.c:10876\n macsec_notify+0x2f5/0x660 drivers/net/macsec.c:4533\n notifier_call_chain+0x1b3/0x3e0 kernel/notifier.c:85\n call_netdevice_notifiers_extack net/core/dev.c:2267 [inline]\n call_netdevice_notifiers net/core/dev.c:2281 [inline]\n netdev_features_change+0x85/0xc0 net/core/dev.c:1570\n __dev_ethtool net/ethtool/ioctl.c:3469 [inline]\n dev_ethtool+0x1536/0x19b0 net/ethtool/ioctl.c:3502\n dev_ioctl+0x392/0x1150 net/core/dev_ioctl.c:759\n\nSucede porque las características inferiores están desincronizadas con las superiores:\n\n __dev_ethtool (real_dev)\n netdev_lock_ops(real_dev)\n ETHTOOL_SFEATURES\n __netdev_features_change\n netdev_sync_upper_features\n deshabilitar LRO en el inferior\n if (old_features != dev->features)\n netdev_features_change\n dispara NETDEV_FEAT_CHANGE\n\tmacsec_notify\n\t NETDEV_FEAT_CHANGE\n\t netdev_update_features (para cada dispositivo macsec)\n\t netdev_sync_lower_features\n\t if (upper_features != lower_features)\n\t netdev_lock_ops(lower) # inferior == real_dev\n\t\t atascado\n\t\t ...\n\n netdev_unlock_ops(real_dev)\n\nSegún el commit af5f54b0ef9e ('net: Bloquear dispositivos de nivel inferior al actualizar características'), omitimos el bloqueo/desbloqueo cuando las características superiores e inferiores están sincronizadas. Asegura que el inferior (real_dev) tenga las características adecuadas después de que se haya creado el enlace macsec. Esto asegura que nunca lleguemos a la situación en la que necesitemos sincronizar las banderas superiores con las inferiores."
}
],
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"affectedData": [
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"id": "CVE-2025-39874",
"options": [
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"role": "CISA Coordinator",
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"weaknesses": [
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"source": "[email protected]",
"type": "Primary",
"description": [
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"lang": "en",
"value": "NVD-CWE-noinfo"
}
]
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"configurations": [
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