macvlan: fix macvlan_get_size() not reserving space for IFLA_MACVLAN_BC_CUTOFF

{
  "id": "9f7ef3a00cd46163557ee778bfe9d964e0c2d52ea1a60b1d519a5c713fb9c034",
  "url": "https://osv.dev/vulnerability/CVE-2026-53013",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "macvlan: fix macvlan_get_size() not reserving space for IFLA_MACVLAN_BC_CUTOFF",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: macvlan: fix macvlan_get_size() not reserving space for IFLA_MACVLAN_BC_CUTOFF macvlan_get_size() does not account for IFLA_MACVLAN_BC_CUTOFF, but macvlan_fill_info() conditionally includes it when port->bc_cutoff != 1. This causes nla_put_s32() to fail with -EMSGSIZE when the netlink skb runs out of space, triggering a WARN_ON in rtnetlink and preventing the interface from being dumped. The bug can be reproduced with: ip link add macvlan0 link eth0 type macvlan mode bridge ip link set macvlan0 type macvlan bc_cutoff 0 ip -d link show macvlan0 # fails with -EMSGSIZE The bc_cutoff feature was added in commit 954d1fa1ac93 (\"macvlan: Add netlink attribute for broadcast cutoff\"), which added the nla_put_s32() call in macvlan_fill_info() but missed adding the corresponding nla_total_size(4) in macvlan_get_size(). A follow-up commit 55cef78c244d (\"macvlan: add forgotten nla_policy for IFLA_MACVLAN_BC_CUTOFF\") fixed the missing nla_policy entry but still did not fix the size calculation.",
    "evidence": "osv:CVE-2026-53013",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "6.6.141",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.12.91",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.18.33",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "7.0.10",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "unknown",
    "structured": {
      "id": "CVE-2026-53013",
      "aliases": [
        "CVE-2026-53013"
      ],
      "affected": [
        {
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              "type": "GIT",
              "events": [
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                {
                  "fixed": "4979252758387b338ca968ba7e0515b0ae2257e3"
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                {
                  "fixed": "77ecfa4e27f282d224215895ddfbeb916fc75e24"
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                {
                  "fixed": "b6b7154e9f5d75b608ceb2d05b376de8c638c40e"
                },
                {
                  "fixed": "1c004f14ccdc11585625c168bb9a7c5e1b8afb0c"
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                {
                  "fixed": "fa92a77b0ed4d5f11a71665a232ac5a54a4b055d"
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          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
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                  "introduced": "6.4.0"
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            {
              "type": "ECOSYSTEM",
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                  "fixed": "6.18.33"
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              "type": "ECOSYSTEM",
              "events": [
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                  "introduced": "6.19.0"
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                {
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          ],
          "package": {
            "name": "Kernel",
            "ecosystem": "Linux"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-53013.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:49.723262151Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/1c004f14ccdc11585625c168bb9a7c5e1b8afb0c",
        "https://git.kernel.org/stable/c/4979252758387b338ca968ba7e0515b0ae2257e3",
        "https://git.kernel.org/stable/c/77ecfa4e27f282d224215895ddfbeb916fc75e24",
        "https://git.kernel.org/stable/c/b6b7154e9f5d75b608ceb2d05b376de8c638c40e",
        "https://git.kernel.org/stable/c/fa92a77b0ed4d5f11a71665a232ac5a54a4b055d",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/53xxx/CVE-2026-53013.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-53013",
        "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
      ],
      "provider_metadata": {
        "cna_assigner": "Linux",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/53xxx/CVE-2026-53013.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-53013",
        "evidence": "/id"
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    ],
    "security_relevant": true,
    "severity_evidence": null
  },
  "source_id": "core-osv",
  "document_id": 517888,
  "published_at": "2026-06-24T16:29:23.856+00:00"
}