nfsd: validate sockaddr length per family in listener_set

{
  "id": "6cfb4e8e97de143964070c6c50937579f429f833db69c45d5ce77ded505bd071",
  "url": "https://osv.dev/vulnerability/CVE-2026-89700",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "nfsd: validate sockaddr length per family in listener_set",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: nfsd: validate sockaddr length per family in listener_set nfsd_sock_nl_policy declares NFSD_A_SOCK_ADDR as a bare NLA_BINARY attribute with no minimum length. A CAP_NET_ADMIN caller can send a 16-byte NFSD_A_SOCK_ADDR with sa_family=AF_INET6, causing a 12-byte OOB read across three consumers (rpc_cmp_addr_port, svc_find_listener, kernel_bind). nfsd_nl_listener_set_doit() also parsed and validated each listener entry inline in two separate loops, interleaved with mutating the running listener configuration. The validation was duplicated, used an open-coded \"nla_len < sizeof(struct sockaddr)\" check that was too short for AF_INET6, and handled a malformed entry inconsistently depending on which loop noticed it. Add an nfsd_nl_validate_listeners() helper that walks the entire list once and confirms each entry parses, carries both an address and a transport name, and is long enough for its address family (sizeof(struct sockaddr_in) for AF_INET, sizeof(struct sockaddr_in6) for AF_INET6, -EAFNOSUPPORT otherwise). Call it before taking nfsd_mutex or creating the serv, so a malformed request fails cleanly with no side effects. Since every entry is known valid by the time the two existing loops run, drop the redundant presence and per-family length checks from both, leaving only the nla_parse_nested() call needed to extract the data.",
    "evidence": "osv:CVE-2026-89700",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "6.12.111",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.18.50",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "7.2.4",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "unknown",
    "structured": {
      "id": "CVE-2026-89700",
      "aliases": [
        "CVE-2026-89700"
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "type": "GIT",
              "events": [
                {
                  "introduced": "16a471177496c8e04a9793812c187a2c1a2192fa"
                },
                {
                  "fixed": "bf85a0f1e45258f90ceeec14772b5769697dfd75"
                },
                {
                  "fixed": "2aca70c18c5f5d06004122861fb151d5fcc57faf"
                },
                {
                  "fixed": "22d0e4752ca88fd84196d22ebeedc905e6540440"
                },
                {
                  "fixed": "bdcc85c2b05a9378d8bd2d65f9fc41440a3cf464"
                }
              ]
            }
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-89700.json"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.10.0"
                },
                {
                  "fixed": "6.12.111"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.13.0"
                },
                {
                  "fixed": "6.18.50"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.19.0"
                },
                {
                  "fixed": "7.2.4"
                }
              ]
            }
          ],
          "package": {
            "name": "Kernel",
            "ecosystem": "Linux"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-89700.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:45.337379901Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/22d0e4752ca88fd84196d22ebeedc905e6540440",
        "https://git.kernel.org/stable/c/2aca70c18c5f5d06004122861fb151d5fcc57faf",
        "https://git.kernel.org/stable/c/bdcc85c2b05a9378d8bd2d65f9fc41440a3cf464",
        "https://git.kernel.org/stable/c/bf85a0f1e45258f90ceeec14772b5769697dfd75",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/89xxx/CVE-2026-89700.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-89700",
        "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/2026/89xxx/CVE-2026-89700.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-89700",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": null
  },
  "source_id": "core-osv",
  "document_id": 513437,
  "published_at": "2026-09-11T19:46:18.076+00:00"
}