ceph: fix num_ops off-by-one when crypto allocation fails

{
  "id": "f35cdc6beaf4e6e1e9281481c026806bab7fec14c699f86800ca66363717a150",
  "url": "https://osv.dev/vulnerability/CVE-2026-46066",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "ceph: fix num_ops off-by-one when crypto allocation fails",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: ceph: fix num_ops off-by-one when crypto allocation fails move_dirty_folio_in_page_array() may fail if the file is encrypted, the dirty folio is not the first in the batch, and it fails to allocate a bounce buffer to hold the ciphertext. When that happens, ceph_process_folio_batch() simply redirties the folio and flushes the current batch -- it can retry that folio in a future batch. However, if this failed folio is not contiguous with the last folio that did make it into the batch, then ceph_process_folio_batch() has already incremented `ceph_wbc->num_ops`; because it doesn't follow through and add the discontiguous folio to the array, ceph_submit_write() -- which expects that `ceph_wbc->num_ops` accurately reflects the number of contiguous ranges (and therefore the required number of \"write extent\" ops) in the writeback -- will panic the kernel: BUG_ON(ceph_wbc->op_idx + 1 != req->r_num_ops); This issue can be reproduced on affected kernels by writing to fscrypt-enabled CephFS file(s) with a 4KiB-written/4KiB-skipped/repeat pattern (total filesize should not matter) and gradually increasing the system's memory pressure until a bounce buffer allocation fails. Fix this crash by decrementing `ceph_wbc->num_ops` back to the correct value when move_dirty_folio_in_page_array() fails, but the folio already started counting a new (i.e. still-empty) extent. The defect corrected by this patch has existed since 2022 (",
    "evidence": "osv:CVE-2026-46066",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "6.6.160",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.12.114",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.18.30",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "7.0.4",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "unknown",
    "structured": {
      "id": "CVE-2026-46066",
      "aliases": [
        "CVE-2026-46066"
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "type": "GIT",
              "events": [
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                {
                  "fixed": "f65a96fe2467a9b184c6ae963d95a260a202c98e"
                },
                {
                  "fixed": "5dd151799d826d3736ae60c2b22cbc9d96a2a613"
                },
                {
                  "fixed": "6200f41d6fcf2ac7e24866431e381cbc914560e4"
                },
                {
                  "fixed": "ba12c1e578890f6337a415b7dedf476c6d455105"
                },
                {
                  "fixed": "a0d9555bf9eaeba34fe6b6bb86f442fe08ba3842"
                }
              ]
            }
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-46066.json"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.6.0"
                },
                {
                  "fixed": "6.6.160"
                }
              ]
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            {
              "type": "ECOSYSTEM",
              "events": [
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                  "introduced": "6.7.0"
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                {
                  "fixed": "6.12.114"
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            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.13.0"
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                {
                  "fixed": "6.18.30"
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              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.19.0"
                },
                {
                  "fixed": "7.0.4"
                }
              ]
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          ],
          "package": {
            "name": "Kernel",
            "ecosystem": "Linux"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-46066.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:36.873906700Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/5dd151799d826d3736ae60c2b22cbc9d96a2a613",
        "https://git.kernel.org/stable/c/6200f41d6fcf2ac7e24866431e381cbc914560e4",
        "https://git.kernel.org/stable/c/a0d9555bf9eaeba34fe6b6bb86f442fe08ba3842",
        "https://git.kernel.org/stable/c/ba12c1e578890f6337a415b7dedf476c6d455105",
        "https://git.kernel.org/stable/c/f65a96fe2467a9b184c6ae963d95a260a202c98e",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/46xxx/CVE-2026-46066.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-46066",
        "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/2026/46xxx/CVE-2026-46066.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-46066",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": null
  },
  "source_id": "core-osv",
  "document_id": 504360,
  "published_at": "2026-05-27T12:57:41.865+00:00"
}