userfaultfd: fix a crash in UFFDIO_MOVE when PMD is a migration entry

{
  "id": "f163b592f5be43adaee242fb56a1eb662ebf13d5609514f70059a1af5368ddf2",
  "url": "https://osv.dev/vulnerability/CVE-2025-38686",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "userfaultfd: fix a crash in UFFDIO_MOVE when PMD is a migration entry",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: userfaultfd: fix a crash in UFFDIO_MOVE when PMD is a migration entry When UFFDIO_MOVE encounters a migration PMD entry, it proceeds with obtaining a folio and accessing it even though the entry is swp_entry_t. Add the missing check and let split_huge_pmd() handle migration entries. While at it also remove unnecessary folio check. [surenb@google.com: remove extra folio check, per David]",
    "evidence": "osv:CVE-2025-38686",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "6.12.43",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.15.11",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.16.2",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "unknown",
    "structured": {
      "id": "CVE-2025-38686",
      "aliases": [
        "CVE-2025-38686"
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "type": "GIT",
              "events": [
                {
                  "introduced": "adef440691bab824e39c1b17382322d195e1fab0"
                },
                {
                  "fixed": "bb81c18dbd42650c844e160cafa7cbb20243a96a"
                },
                {
                  "fixed": "1202abad7a7ccd28c426d2844771a387b07629a4"
                },
                {
                  "fixed": "7f1101a0a181243ad587ececdffc4845f035549f"
                },
                {
                  "fixed": "aba6faec0103ed8f169be8dce2ead41fcb689446"
                }
              ]
            }
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2025-38686.json"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.8.0"
                },
                {
                  "fixed": "6.12.43"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.13.0"
                },
                {
                  "fixed": "6.15.11"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.16.0"
                },
                {
                  "fixed": "6.16.2"
                }
              ]
            }
          ],
          "package": {
            "name": "Kernel",
            "ecosystem": "Linux"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2025-38686.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:39.625388870Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/1202abad7a7ccd28c426d2844771a387b07629a4",
        "https://git.kernel.org/stable/c/7f1101a0a181243ad587ececdffc4845f035549f",
        "https://git.kernel.org/stable/c/aba6faec0103ed8f169be8dce2ead41fcb689446",
        "https://git.kernel.org/stable/c/bb81c18dbd42650c844e160cafa7cbb20243a96a",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/38xxx/CVE-2025-38686.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2025-38686",
        "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-2025-38686.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2025-38686",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": null
  },
  "source_id": "core-osv",
  "document_id": 507243,
  "published_at": "2025-09-04T15:32:40.771+00:00"
}