{"id":"AZL-90509","summary":"CVE-2026-52990 affecting package kernel 6.6.150.1-1","details":"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-\u003elock)\n      add mark_B(evictable) to list\n      spin_unlock(conn-\u003elock)\n    return\n\n    /* ---- gap: no lock held ---- */\n\n                                      fsnotify_detach_mark(mark_A):\n                                        spin_lock(mark_A-\u003elock)\n                                        clear ATTACHED flag on mark_A\n                                        spin_unlock(mark_A-\u003elock)\n                                        fsnotify_put_mark(mark_A)\n\n    fsnotify_recalc_mask():\n      spin_lock(conn-\u003elock)\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        -\u003e HAS_IREF transitions true -\u003e false\n        -\u003e returns inode pointer\n      spin_unlock(conn-\u003elock)\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 -\u003e false of HAS_IREF flag from\nfsnotify_recalc_mask() (Thread A) to fsnotify_put_mark() (thread B).","modified":"2026-09-03T05:27:10Z","published":"2026-06-24T17:17:09Z","upstream":["CVE-2026-52990"],"references":[{"type":"WEB","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-52990"}],"affected":[{"package":{"name":"kernel","ecosystem":"Azure Linux:3","purl":"pkg:rpm/azure-linux/kernel"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"last_affected":"6.6.150.1-1"}]}],"database_specific":{"source":"https://github.com/microsoft/AzureLinuxVulnerabilityData/blob/main/osv/AZL-90509.json"}}],"schema_version":"1.9.0"}