kho: fix size calculation in kho_preserved_memory_reserve()

{
  "id": "e8f93cfd748c6fceee7d272c67221ae059218228576be8c714cdcebdda28712e",
  "url": "https://osv.dev/vulnerability/CVE-2026-89568",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "kho: fix size calculation in kho_preserved_memory_reserve()",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: kho: fix size calculation in kho_preserved_memory_reserve() kho_preserved_memory_reserve() calculates the size of a preservation by doing 1 << (order + PAGE_SHIFT). Since the '1' is a 32-bit integer, it can only be shifted by 31. That is, it will only work for preservations up to 2 GiB. Larger preservations will trigger undefined behaviour. While preservations larger than 2 GiB can't be obtained via folios currently, they can be obtained via kho_preserve_pages(). For example, memblock reserve_mem uses kho_preserve_pages(). Reservations larger than 2 GiB are valid and will trigger this bug if properly aligned. Fix it by using 1UL for shifting.",
    "evidence": "osv:CVE-2026-89568",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "6.18.57",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "7.2.4",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "unknown",
    "structured": {
      "id": "CVE-2026-89568",
      "aliases": [
        "CVE-2026-89568"
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "type": "GIT",
              "events": [
                {
                  "introduced": "fc33e4b44b2717feba2f6f07ce7943a96499c9ec"
                },
                {
                  "fixed": "0692a8fdf0222af130c8ea97426f1c3bf3814905"
                },
                {
                  "fixed": "42a6f03cf352eb6e6dbeef95e75e686f4cdb9bd1"
                },
                {
                  "fixed": "3a0b8fa2eb36afc88b62a95f33f0c77c71fa5ded"
                }
              ]
            }
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-89568.json"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.16.0"
                },
                {
                  "fixed": "6.18.57"
                }
              ]
            },
            {
              "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-2026-89568.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:41.288205036Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/0692a8fdf0222af130c8ea97426f1c3bf3814905",
        "https://git.kernel.org/stable/c/3a0b8fa2eb36afc88b62a95f33f0c77c71fa5ded",
        "https://git.kernel.org/stable/c/42a6f03cf352eb6e6dbeef95e75e686f4cdb9bd1",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/89xxx/CVE-2026-89568.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-89568",
        "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-2026-89568.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-89568",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": null
  },
  "source_id": "core-osv",
  "document_id": 509140,
  "published_at": "2026-09-11T19:44:38.078+00:00"
}