fuse-uring: fix moving cancelled entry to ent_in_userspace list

{
  "id": "f9405521f941d1fe7446015c9182d6f8549cec797af279b0ddce4e886fbac01a",
  "url": "https://osv.dev/vulnerability/CVE-2026-64263",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "fuse-uring: fix moving cancelled entry to ent_in_userspace list",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: fuse-uring: fix moving cancelled entry to ent_in_userspace list fuse_uring_cancel() moves entries that are available (these have no reqs attached) to the ent_in_userspace list. ent_list_request_expired() checks the first entry on ent_in_userspace and dereferences ent->fuse_req unconditionally, which will crash on a cancelled entry that was moved to this list. Fix this by freeing the entry and dropping queue_refs directly in fuse_uring_cancel(). This is safe because cancel is the cancel handler itself - after io_uring_cmd_done(), no more cancels will be dispatched for this command, and teardown serializes with cancel via queue->lock. Since cancel now decrements queue_refs, fuse_uring_abort() must no longer gate fuse_uring_abort_end_requests() on queue_refs > 0, as cancelled entries may have already dropped queue_refs while requests are still queued. Remove the gate so abort always flushes requests and stops queues.",
    "evidence": "osv:CVE-2026-64263",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "6.18.39",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "7.1.4",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "unknown",
    "structured": {
      "id": "CVE-2026-64263",
      "aliases": [
        "CVE-2026-64263"
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "type": "GIT",
              "events": [
                {
                  "introduced": "4fea593e625cd50d4d11be227007849b12f17bfb"
                },
                {
                  "fixed": "50f3e03db823cabc41fe35c27d77c2bdb112baad"
                },
                {
                  "fixed": "e8afc85acdf329361b2d8df2ad9b52364686235f"
                },
                {
                  "fixed": "198f45eeb9f78b2a2d6d8be95e4e43468eb2c6bc"
                }
              ]
            }
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-64263.json"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.16.0"
                },
                {
                  "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-2026-64263.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:23.500476488Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/198f45eeb9f78b2a2d6d8be95e4e43468eb2c6bc",
        "https://git.kernel.org/stable/c/50f3e03db823cabc41fe35c27d77c2bdb112baad",
        "https://git.kernel.org/stable/c/e8afc85acdf329361b2d8df2ad9b52364686235f",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/64xxx/CVE-2026-64263.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-64263",
        "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-2026-64263.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-64263",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": null
  },
  "source_id": "core-osv",
  "document_id": 489917,
  "published_at": "2026-07-25T08:49:13.217+00:00"
}