io_uring/query: cap user size passed to copy_struct_to_user

{
  "id": "cb095f7002c9e807f3bb1a41622fc8ae755cf48a28ce6a8ed656dbde5da409d0",
  "url": "https://osv.dev/vulnerability/CVE-2026-81009",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "io_uring/query: cap user size passed to copy_struct_to_user",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: io_uring/query: cap user size passed to copy_struct_to_user io_handle_query_entry() clamps hdr.size for the inbound copy_from_user() but keeps the original user value as usize. copy_struct_to_user() uses that usize and, when it is larger than the kernel result, clear_user()s the trailing bytes. As hdr.size is a __u32, a query can request nearly 4 GiB of zeroing, including on the error path where res_size stays 0. The interface is reachable without a ring via IORING_REGISTER_QUERY. Reject sizes larger than PAGE_SIZE, as recommended for copy_struct_* interfaces.",
    "evidence": "osv:CVE-2026-81009",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "6.18.50",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "7.2.4",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "unknown",
    "structured": {
      "id": "CVE-2026-81009",
      "aliases": [
        "CVE-2026-81009"
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "type": "GIT",
              "events": [
                {
                  "introduced": "c265ae75f900cea4e415230a77b5d152377627dd"
                },
                {
                  "fixed": "417e02f7b6051765b91cf1289071882eebd172e0"
                },
                {
                  "fixed": "2b8ad4981ecedb14c1fdd811ab977010b23933e6"
                },
                {
                  "fixed": "ba77efee1b95b4ad7559b1cdbe7cd7fa36dca95b"
                }
              ]
            }
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-81009.json"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.18.0"
                },
                {
                  "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-2026-81009.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:25.042386198Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/2b8ad4981ecedb14c1fdd811ab977010b23933e6",
        "https://git.kernel.org/stable/c/417e02f7b6051765b91cf1289071882eebd172e0",
        "https://git.kernel.org/stable/c/ba77efee1b95b4ad7559b1cdbe7cd7fa36dca95b",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/81xxx/CVE-2026-81009.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-81009",
        "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/2026/81xxx/CVE-2026-81009.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-81009",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": null
  },
  "source_id": "core-osv",
  "document_id": 491666,
  "published_at": "2026-09-11T19:43:00.074+00:00"
}