{
  "affected": [
    {
      "ecosystem_specific": {
        "urgency": "not yet assigned"
      },
      "package": {
        "ecosystem": "Debian:12",
        "name": "linux"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "ecosystem_specific": {
        "urgency": "not yet assigned"
      },
      "package": {
        "ecosystem": "Debian:13",
        "name": "linux"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "ecosystem_specific": {
        "urgency": "not yet assigned"
      },
      "package": {
        "ecosystem": "Debian:14",
        "name": "linux"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "details": "In the Linux kernel, the following vulnerability has been resolved:  nfsd: fix UAF in async copy cancel and shutdown  An async copy could be freed or used after free while a teardown caller (OFFLOAD_CANCEL, nfsd4_shutdown_copy, nfsd4_cancel_copy_by_sb) raced the copy kthread:    - find_async_copy() bumped copy-\u003erefcount but left the copy on     clp-\u003easync_copies, so the reaper's cleanup_async_copy() could run     release_copy_files() concurrently with a cancel/shutdown caller. Both     put and NULL nf_src/nf_dst without a common lock, double-putting the     nfsd_file and freeing it early.    - nfsd4_do_async_copy() set NFSD4_COPY_F_STOPPED before its final uses     of the copy (nfsd_update_cmtime_attr() on copy-\u003enf_dst,     nfsd4_send_cb_offload()). nfsd4_stop_copy() treats a set STOPPED bit     as \"kthread done, skip kthread_stop()\", so a teardown caller ran     release_copy_files() -- which puts and NULLs nf_dst -- while the     kthread still dereferenced it (NULL/UAF).    - copy-\u003ecopy_task was never pinned. The one-shot kthread self-reaps on     return, so kthread_stop()'s get_task_struct() could touch a freed     task_struct.    - co_cb is embedded in the copy, but nfsd4_send_cb_offload() held a     reference only on the client, so a concurrent teardown could free     the copy while the CB_OFFLOAD callback was in flight.  Fix the teardown lifetime as a whole:    - find_async_copy() unlinks the copy (clear cp_clp, list_del_init)     under async_lock; the cancel, shutdown, and sb-cancel paths drop the     list-membership reference via nfs4_put_copy() after nfsd4_stop_copy().     Drop the now-redundant list_del fixup from cleanup_async_copy().    - Because unlinking hides the copy from the reaper, its     cleanup_async_copy() can no longer remove the copy's s2s_cp_stateids     entry; the cancel/shutdown/sb-cancel paths now call     nfs4_free_copy_state() themselves (while cp_clp is still valid) so     the entry does not dangle at freed memory for the laundromat and     manage_cpntf_state() to dereference.    - Give the kthread its own reference, taken in nfsd4_copy() before     wake_up_process() and dropped at the end of nfsd4_do_async_copy();     call wake_up_process() before list_add().    - Pin the task_struct with get_task_struct() in nfsd4_copy(), released     in nfs4_put_copy(), so kthread_stop() is safe whenever the kthread     exits. Set NFSD4_COPY_F_STOPPED only in nfsd4_stop_copy(), which now     always kthread_stop()s before release_copy_files(); completion is     still reported via NFSD4_COPY_F_COMPLETED, so     nfsd4_has_active_async_copies() is unaffected. Each teardown caller     removes the copy from clp-\u003easync_copies first, so kthread_stop() runs     exactly once.    - Take a copy reference in nfsd4_send_cb_offload(), dropped in     nfsd4_cb_offload_release(). The kthread still holds its own reference     there, so the refcount_inc() cannot race the final free.    - Read cp_clp with smp_load_acquire() to pair with the unordered     set_bit()/clear_bit() writers (Documentation/atomic_bitops.rst).",
  "id": "DEBIAN-CVE-2026-89675",
  "modified": "2026-09-14T08:47:42.451144776Z",
  "published": "2026-09-11T20:19:54.143Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://security-tracker.debian.org/tracker/CVE-2026-89675"
    }
  ],
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ],
  "upstream": [
    "CVE-2026-89675"
  ]
}