{"cve":"CVE-2026-52990","nvd":{"published":"2026-06-24T17:17:09.833","modified":"2026-10-21T13:19:07.667","status":"Modified","description":"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).","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","score":5.5},"cwes":[],"references":["https://git.kernel.org/stable/c/4aca914ac152f5d055ddcb36704d1e539ac08977","https://git.kernel.org/stable/c/5c80289503da3658e3df80280598c68d181eadbd","https://git.kernel.org/stable/c/8c8afa6444e6bdc145d2bf2f3aeeca6da3e36b42","https://git.kernel.org/stable/c/926ec3937b28d30c08427053c8d8af7f9e086d82","https://git.kernel.org/stable/c/b740cc86816bbc87902ae9db74cd21abde3c8d63"],"products":["linux:linux_kernel"],"source":"nvd","synced_at":"2026-10-22T16:41:11.231219466+00:00"},"epss":{"cve":"CVE-2026-52990","score":0.00128,"percentile":0.02417,"date":"2026-10-25"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}