netfilter: nf_conntrack: fix crash due to removal of uninitialised entry

{
  "id": "1299822a778a5c202bb1bee1024aef97f5aa697e1acd4f4675837ef5f43bdd56",
  "url": "https://osv.dev/vulnerability/CVE-2025-38472",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "netfilter: nf_conntrack: fix crash due to removal of uninitialised entry",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: netfilter: nf_conntrack: fix crash due to removal of uninitialised entry A crash in conntrack was reported while trying to unlink the conntrack entry from the hash bucket list: [exception RIP: __nf_ct_delete_from_lists+172] [..] #7 [ff539b5a2b043aa0] nf_ct_delete at ffffffffc124d421 [nf_conntrack] #8 [ff539b5a2b043ad0] nf_ct_gc_expired at ffffffffc124d999 [nf_conntrack] #9 [ff539b5a2b043ae0] __nf_conntrack_find_get at ffffffffc124efbc [nf_conntrack] [..] The nf_conn struct is marked as allocated from slab but appears to be in a partially initialised state: ct hlist pointer is garbage; looks like the ct hash value (hence crash). ct->status is equal to IPS_CONFIRMED|IPS_DYING, which is expected ct->timeout is 30000 (=30s), which is unexpected. Everything else looks like normal udp conntrack entry. If we ignore ct->status and pretend its 0, the entry matches those that are newly allocated but not yet inserted into the hash: - ct hlist pointers are overloaded and store/cache the raw tuple hash - ct->timeout matches the relative time expected for a new udp flow rather than the absolute 'jiffies' value. If it were not for the presence of IPS_CONFIRMED, __nf_conntrack_find_get() would have skipped the entry. Theory is that we did hit following race: cpu x cpu y cpu z found entry E found entry E E is expired nf_ct_delete() return E to rcu slab init_conntrack E is re-inited, ct->status set to 0 reply tuplehash hnnode.",
    "evidence": "osv:CVE-2025-38472",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "6.1.147",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.6.100",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.12.40",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.15.8",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "critical",
    "structured": {
      "id": "CVE-2025-38472",
      "aliases": [
        "CVE-2025-38472"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"
        }
      ],
      "affected": [
        {
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              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "type": "GIT",
              "events": [
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                  "fixed": "a47ef874189d47f934d0809ae738886307c0ea22"
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                {
                  "fixed": "76179961c423cd698080b5e4d5583cf7f4fcdde9"
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                {
                  "fixed": "fc38c249c622ff5e3011b8845fd49dbfd9289afc"
                },
                {
                  "fixed": "938ce0e8422d3793fe30df2ed0e37f6bc0598379"
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                  "fixed": "2d72afb340657f03f7261e9243b44457a9228ac7"
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              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
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              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
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          "versions": [
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            "v5.18.18",
            "v5.18.17",
            "v5.18.16",
            "v5.18.15",
            "v5.18.14",
            "v5.18.13"
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          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2025-38472.json"
          }
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        {
          "ranges": [
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              "type": "ECOSYSTEM",
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                  "introduced": "6.13.0"
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          "package": {
            "name": "Kernel",
            "ecosystem": "Linux"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2025-38472.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:45.997329695Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/2d72afb340657f03f7261e9243b44457a9228ac7",
        "https://git.kernel.org/stable/c/76179961c423cd698080b5e4d5583cf7f4fcdde9",
        "https://git.kernel.org/stable/c/938ce0e8422d3793fe30df2ed0e37f6bc0598379",
        "https://git.kernel.org/stable/c/a47ef874189d47f934d0809ae738886307c0ea22",
        "https://git.kernel.org/stable/c/fc38c249c622ff5e3011b8845fd49dbfd9289afc",
        "https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/38xxx/CVE-2025-38472.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2025-38472",
        "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/2025/38xxx/CVE-2025-38472.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2025-38472",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 513975,
  "published_at": "2025-07-28T11:21:33.977+00:00"
}