fkie_cve-2025-39874
Vulnerability from fkie_nvd
Published
2025-09-23 06:15
Modified
2025-12-12 18:48
Severity ?
5.5 (Medium) - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Summary
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.
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/0f82c3ba66c6b2e3cde0f255156a753b108ee9dcPatch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/d7624629ccf47135c65fef0701fa0d9a115b87f3Patch
Impacted products
Vendor Product Version
linux linux_kernel *
linux linux_kernel 6.17
linux linux_kernel 6.17
linux linux_kernel 6.17
linux linux_kernel 6.17
linux linux_kernel 6.17


To clipboard 

{
  "configurations": [
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      "nodes": [
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              "versionStartIncluding": "6.15",
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  "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-\u003efeatures)\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."
    }
  ],
  "id": "CVE-2025-39874",
  "lastModified": "2025-12-12T18:48:05.237",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "LOCAL",
          "availabilityImpact": "HIGH",
          "baseScore": 5.5,
          "baseSeverity": "MEDIUM",
          "confidentialityImpact": "NONE",
          "integrityImpact": "NONE",
          "privilegesRequired": "LOW",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 1.8,
        "impactScore": 3.6,
        "source": "nvd@nist.gov",
        "type": "Primary"
      }
    ]
  },
  "published": "2025-09-23T06:15:46.813",
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          "value": "NVD-CWE-noinfo"
        }
      ],
      "source": "nvd@nist.gov",
      "type": "Primary"
    }
  ]
}


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