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CVE-2026-52990

Estado: AnalizadaMedia (5.5)—

In the Linux kernel, the following vulnerability has been resolved:

fsnotify: fix inode reference leak in fsnotify_recalc_mask()

fsnotify_recalc_mask() fails to handle the return value of __fsnotify_recalc_mask(), which may return an inode pointer that needs to be released via fsnotify_drop_object() when the connector's HAS_IREF flag transitions from set to cleared.

This manifests as a hung task with the following call trace:

The race window that triggers the iref leak:

Fix this by deferring the transition true -> false of HAS_IREF flag from fsnotify_recalc_mask() (Thread A) to fsnotify_put_mark() (thread B).

Detalles técnicos trazas, registros y código del informe original
  INFO: task umount:1234 blocked for more than 120 seconds.
  Call Trace:
   __schedule
   schedule
   fsnotify_sb_delete
   generic_shutdown_super
   kill_anon_super
   cleanup_mnt
   task_work_run
   do_exit
   do_group_exit

  Thread A (adding mark)              Thread B (removing mark)
  ──────────────────────              ────────────────────────
  fsnotify_add_mark_locked():
    fsnotify_add_mark_list():
      spin_lock(conn->lock)
      add mark_B(evictable) to list
      spin_unlock(conn->lock)
    return

    /* ---- gap: no lock held ---- */

                                      fsnotify_detach_mark(mark_A):
                                        spin_lock(mark_A->lock)
                                        clear ATTACHED flag on mark_A
                                        spin_unlock(mark_A->lock)
                                        fsnotify_put_mark(mark_A)

    fsnotify_recalc_mask():
      spin_lock(conn->lock)
      __fsnotify_recalc_mask():
        /* mark_A skipped: ATTACHED cleared */
        /* only mark_B(evictable) remains */
        want_iref = false
        has_iref = true  /* not yet cleared */
        -> HAS_IREF transitions true -> false
        -> returns inode pointer
      spin_unlock(conn->lock)
      /* BUG: return value discarded!
       * iput() and fsnotify_put_sb_watched_objects()
       * are never called */

CVSS

Probabilidad de explotación (EPSS)

EPSS (Exploit Prediction Scoring System, de FIRST) estima la probabilidad de que una vulnerabilidad sea explotada en 30 días. Complementa a CVSS (impacto) y a CISA KEV (explotación confirmada).

Tecnologías afectadas (1)

Linux — Linux Kernel

CWE

Referencias

JSON original (NVD)

Mostrar
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          "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
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      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nfsnotify: fix inode reference leak in fsnotify_recalc_mask()\n\nfsnotify_recalc_mask() fails to handle the return value of\n__fsnotify_recalc_mask(), which may return an inode pointer that needs\nto be released via fsnotify_drop_object() when the connector's HAS_IREF\nflag transitions from set to cleared.\n\nThis manifests as a hung task with the following call trace:\n\n  INFO: task umount:1234 blocked for more than 120 seconds.\n  Call Trace:\n   __schedule\n   schedule\n   fsnotify_sb_delete\n   generic_shutdown_super\n   kill_anon_super\n   cleanup_mnt\n   task_work_run\n   do_exit\n   do_group_exit\n\nThe race window that triggers the iref leak:\n\n  Thread A (adding mark)              Thread B (removing mark)\n  ──────────────────────              ────────────────────────\n  fsnotify_add_mark_locked():\n    fsnotify_add_mark_list():\n      spin_lock(conn->lock)\n      add mark_B(evictable) to list\n      spin_unlock(conn->lock)\n    return\n\n    /* ---- gap: no lock held ---- */\n\n                                      fsnotify_detach_mark(mark_A):\n                                        spin_lock(mark_A->lock)\n                                        clear ATTACHED flag on mark_A\n                                        spin_unlock(mark_A->lock)\n                                        fsnotify_put_mark(mark_A)\n\n    fsnotify_recalc_mask():\n      spin_lock(conn->lock)\n      __fsnotify_recalc_mask():\n        /* mark_A skipped: ATTACHED cleared */\n        /* only mark_B(evictable) remains */\n        want_iref = false\n        has_iref = true  /* not yet cleared */\n        -> HAS_IREF transitions true -> false\n        -> returns inode pointer\n      spin_unlock(conn->lock)\n      /* BUG: return value discarded!\n       * iput() and fsnotify_put_sb_watched_objects()\n       * are never called */\n\nFix this by deferring the transition true -> false of HAS_IREF flag from\nfsnotify_recalc_mask() (Thread A) to fsnotify_put_mark() (thread B)."
    }
  ],
  "lastModified": "2026-07-14T16:42:40.580",
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