ghsa-rmcq-9vcc-9423
Vulnerability from github
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.
{
"affected": [],
"aliases": [
"CVE-2025-39874"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2025-09-23T06:15:46Z",
"severity": null
},
"details": "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": "GHSA-rmcq-9vcc-9423",
"modified": "2025-09-23T06:30:27Z",
"published": "2025-09-23T06:30:27Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2025-39874"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/0f82c3ba66c6b2e3cde0f255156a753b108ee9dc"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/d7624629ccf47135c65fef0701fa0d9a115b87f3"
}
],
"schema_version": "1.4.0",
"severity": []
}
Sightings
| Author | Source | Type | Date |
|---|
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