fsnotify: fix inode reference leak in fsnotify_recalc_mask()

Summary

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: 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 The race window that triggers the iref leak: 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 */ Fix this by deferring the transition true -> false of HAS_IREF flag from fsnotify_recalc_mask() (Thread A) to fsnotify_put_mark() (thread B).

Timeline

1. Jun 24, 2026, 4:29 PM UTCCVE published
2. Oct 21, 2026, 12:41 PM UTCRecord last updated

Affected versions

• Linux Linux

  From c3638b5b13740fa31762d414bbce8b7a694e582a · fixed in 926ec3937b28d30c08427053c8d8af7f9e086d82; From c3638b5b13740fa31762d414bbce8b7a694e582a · fixed in 8c8afa6444e6bdc145d2bf2f3aeeca6da3e36b42; From c3638b5b13740fa31762d414bbce8b7a694e582a · fixed in b740cc86816bbc87902ae9db74cd21abde3c8d63; From c3638b5b13740fa31762d414bbce8b7a694e582a · fixed in 5c80289503da3658e3df80280598c68d181eadbd; From c3638b5b13740fa31762d414bbce8b7a694e582a · fixed in 4aca914ac152f5d055ddcb36704d1e539ac08977; From 5.10.220 · fixed in 5.11; From 5.15.154 · fixed in 5.16

• Linux Linux

  5.19

• KernelLinux

  From 5.19.0 · fixed in 6.6.160; From 6.7.0 · fixed in 6.12.91; From 6.13.0 · fixed in 6.18.33; From 6.19.0 · fixed in 7.0.10

References 5