FKIE_CVE-2026-80925

Vulnerability from fkie_nvd - Published: 2026-09-09 17:17 - Updated: 2026-10-30 13:20
Severity
Summary
In the Linux kernel, the following vulnerability has been resolved: vlan: fix skb_under_panic and races when toggling HW VLAN offload Toggling hardware VLAN TX offload (NETIF_F_HW_VLAN_CTAG_TX or NETIF_F_HW_VLAN_STAG_TX) on a lower device invokes vlan_transfer_features(), which dynamically changed vlandev->hard_header_len. This causes two issues: 1. Lockless TX paths (e.g. packet_snd in af_packet.c, ip6_finish_output2) read dev->hard_header_len without holding RTNL lock. Mutating hard_header_len dynamically under RTNL creates a data race where upper layers reserve insufficient headroom based on a stale hard_header_len, resulting in skb_under_panic when vlan_dev_hard_header() is called. 2. In addition, vlan_transfer_features() updated hard_header_len without updating header_ops, causing a mismatch between allocated headroom and header creation. Always setting dev->hard_header_len = real_dev->hard_header_len and dev->needed_headroom = real_dev->needed_headroom + VLAN_HLEN unconditionally ensures: - dev->hard_header_len remains 100% static and immutable at real_dev->hard_header_len, eliminating all dynamic runtime updates and data races on hard_header_len. - Upper layers allocating skbs via LL_RESERVED_SPACE() will always reserve sufficient headroom for software VLAN tag insertion (real_dev->hard_header_len + real_dev->needed_headroom + VLAN_HLEN). - vlandev inherits real_dev->needed_tailroom so underlying trailer/padding/ICV requirements are honored. - AF_PACKET SOCK_RAW network header offsets remain correctly aligned at real_dev->hard_header_len. - vlan_header_ops is used unconditionally. Note to stable teams: Make sure to backport these commits: e16e960d55a4 ("ipvlan: inherit needed_headroom and needed_tailroom from phy_dev") cef51860becd ("macvlan: inherit needed_headroom and needed_tailroom from lowerdev")
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/1517d1996b5236fe69eccd9d253f725e06996eb1
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/447cbe95ebb95392b5d8f6a01c0556826919ce23
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/69f2fc6e761ee68a4c0c8e416ae88c573d4d7319
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/a29f3b884ba50217e6f50414f568073221e2bb07
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/b30fe4de285b9bdaf9508740191f69f7cd83b8fa
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/b38d7a4bc9c17e1d437696da25f9fbc286614d9d
Impacted products
Vendor Product Version
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/8021q/vlan_dev.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "69f2fc6e761ee68a4c0c8e416ae88c573d4d7319",
              "status": "affected",
              "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2",
              "versionType": "git"
            },
            {
              "lessThan": "b38d7a4bc9c17e1d437696da25f9fbc286614d9d",
              "status": "affected",
              "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2",
              "versionType": "git"
            },
            {
              "lessThan": "b30fe4de285b9bdaf9508740191f69f7cd83b8fa",
              "status": "affected",
              "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2",
              "versionType": "git"
            },
            {
              "lessThan": "1517d1996b5236fe69eccd9d253f725e06996eb1",
              "status": "affected",
              "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2",
              "versionType": "git"
            },
            {
              "lessThan": "a29f3b884ba50217e6f50414f568073221e2bb07",
              "status": "affected",
              "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2",
              "versionType": "git"
            },
            {
              "lessThan": "447cbe95ebb95392b5d8f6a01c0556826919ce23",
              "status": "affected",
              "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "net/8021q/vlan_dev.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "2.6.12"
            },
            {
              "lessThan": "2.6.12",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.1.*",
              "status": "unaffected",
              "version": "6.1.191",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.158",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.111",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.51",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.3",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nvlan: fix skb_under_panic and races when toggling HW VLAN offload\n\nToggling hardware VLAN TX offload (NETIF_F_HW_VLAN_CTAG_TX or\nNETIF_F_HW_VLAN_STAG_TX) on a lower device invokes vlan_transfer_features(),\nwhich dynamically changed vlandev-\u003ehard_header_len.\n\nThis causes two issues:\n1. Lockless TX paths (e.g. packet_snd in af_packet.c, ip6_finish_output2)\n   read dev-\u003ehard_header_len without holding RTNL lock. Mutating\n   hard_header_len dynamically under RTNL creates a data race where upper\n   layers reserve insufficient headroom based on a stale hard_header_len,\n   resulting in skb_under_panic when vlan_dev_hard_header() is called.\n2. In addition, vlan_transfer_features() updated hard_header_len without\n   updating header_ops, causing a mismatch between allocated headroom\n   and header creation.\n\nAlways setting dev-\u003ehard_header_len = real_dev-\u003ehard_header_len and\ndev-\u003eneeded_headroom = real_dev-\u003eneeded_headroom + VLAN_HLEN unconditionally\nensures:\n- dev-\u003ehard_header_len remains 100% static and immutable at real_dev-\u003ehard_header_len,\n  eliminating all dynamic runtime updates and data races on hard_header_len.\n- Upper layers allocating skbs via LL_RESERVED_SPACE() will always reserve\n  sufficient headroom for software VLAN tag insertion (real_dev-\u003ehard_header_len +\n  real_dev-\u003eneeded_headroom + VLAN_HLEN).\n- vlandev inherits real_dev-\u003eneeded_tailroom so underlying trailer/padding/ICV\n  requirements are honored.\n- AF_PACKET SOCK_RAW network header offsets remain correctly aligned at\n  real_dev-\u003ehard_header_len.\n- vlan_header_ops is used unconditionally.\n\nNote to stable teams: Make sure to backport these commits:\n\ne16e960d55a4 (\"ipvlan: inherit needed_headroom and needed_tailroom from phy_dev\")\ncef51860becd (\"macvlan: inherit needed_headroom and needed_tailroom from lowerdev\")"
    }
  ],
  "id": "CVE-2026-80925",
  "lastModified": "2026-10-30T13:20:13.850",
  "metrics": {},
  "published": "2026-09-09T17:17:47.763",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/1517d1996b5236fe69eccd9d253f725e06996eb1"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/447cbe95ebb95392b5d8f6a01c0556826919ce23"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/69f2fc6e761ee68a4c0c8e416ae88c573d4d7319"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/a29f3b884ba50217e6f50414f568073221e2bb07"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/b30fe4de285b9bdaf9508740191f69f7cd83b8fa"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/b38d7a4bc9c17e1d437696da25f9fbc286614d9d"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Received"
}



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