block: skip sync_blockdev() on surprise removal in bdev_mark_dead()

{
  "id": "c4170866665e5efcbadd768a913f95be2fa25893b84608688fc918d943471bd0",
  "url": "https://osv.dev/vulnerability/CVE-2026-64326",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "block: skip sync_blockdev() on surprise removal in bdev_mark_dead()",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: block: skip sync_blockdev() on surprise removal in bdev_mark_dead() bdev_mark_dead()'s @surprise == true means the device is already gone. The filesystem callback fs_bdev_mark_dead() honours this and skips sync_filesystem(), but the bare block device path (no ->mark_dead op) lost its !surprise guard when the holder ->mark_dead callback was wired up (see Fixes), and now calls sync_blockdev() unconditionally, which can hang forever waiting on writeback that can no longer complete. syzkaller hit this via nvme_reset_work()'s \"I/O queues lost\" path: nvme_mark_namespaces_dead() -> blk_mark_disk_dead() -> bdev_mark_dead(bdev, true) -> sync_blockdev() blocks in folio_wait_writeback(), wedging the reset worker and every task waiting on it. Skip the sync on surprise removal, matching fs_bdev_mark_dead(); invalidate_bdev() still runs. Orderly removal (surprise == false) is unchanged. Found by FuzzNvme(Syzkaller with FEMU fuzzing framework).",
    "evidence": "osv:CVE-2026-64326",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "6.6.145",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.12.96",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.18.39",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "7.1.4",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "unknown",
    "structured": {
      "id": "CVE-2026-64326",
      "aliases": [
        "CVE-2026-64326"
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "type": "GIT",
              "events": [
                {
                  "introduced": "d8530de5a6e82be0ce17a5fdf727a394bcf6444c"
                },
                {
                  "fixed": "d6998ddd507c81e3829489a6ead23f17f5acb7fe"
                },
                {
                  "fixed": "f41cf35ee2a1e31374b3f54e7579c55153506e70"
                },
                {
                  "fixed": "9818bcae3c0ca1dde4b9a334125c46676e0a9b29"
                },
                {
                  "fixed": "aa4c4a9315764b2b7a7182e72cc5ea87520436b4"
                },
                {
                  "fixed": "49f06cff50a4ccf3b7a1a662ceb892b3b21a527a"
                }
              ]
            }
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-64326.json"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.6.0"
                },
                {
                  "fixed": "6.6.145"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.7.0"
                },
                {
                  "fixed": "6.12.96"
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              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.13.0"
                },
                {
                  "fixed": "6.18.39"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.19.0"
                },
                {
                  "fixed": "7.1.4"
                }
              ]
            }
          ],
          "package": {
            "name": "Kernel",
            "ecosystem": "Linux"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-64326.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:46.494476778Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/49f06cff50a4ccf3b7a1a662ceb892b3b21a527a",
        "https://git.kernel.org/stable/c/9818bcae3c0ca1dde4b9a334125c46676e0a9b29",
        "https://git.kernel.org/stable/c/aa4c4a9315764b2b7a7182e72cc5ea87520436b4",
        "https://git.kernel.org/stable/c/d6998ddd507c81e3829489a6ead23f17f5acb7fe",
        "https://git.kernel.org/stable/c/f41cf35ee2a1e31374b3f54e7579c55153506e70",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/64xxx/CVE-2026-64326.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-64326",
        "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/2026/64xxx/CVE-2026-64326.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-64326",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": null
  },
  "source_id": "core-osv",
  "document_id": 514462,
  "published_at": "2026-07-25T08:49:54.327+00:00"
}