{"id":"AZL-100904","summary":"CVE-2026-89655 affecting package kernel 6.6.150.1-1","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nceph: fix UAF in __kick_flushing_caps() on cf entry freed during unlock\n\nlist_for_each_entry() iterates ci-\u003ei_cap_flush_list but drops\ni_ceph_lock to send cap messages.  During the unlock window,\nhandle_cap_flush_ack() can acquire i_ceph_lock, detach cf entries\nwith tid \u003c= flush_tid from the list, release i_ceph_lock, and free\nthem via ceph_free_cap_flush() outside any lock.  When the original\nthread reacquires i_ceph_lock and the for-loop macro advances via\ncf = list_next_entry(cf, i_list), it dereferences cf-\u003ei_list.next\non freed memory.\n\nThe race timeline:\n\n  __kick_flushing_caps()              handle_cap_flush_ack()\n  -----------------------             -----------------------\n  holds i_ceph_lock        \u003c---\n  iterates to cf (tid=10)\n  prepares FLUSH message\n  drops i_ceph_lock        \u003c---\n  __send_cap() ── FLUSH(tid=10)\n\t                              MDS sends FLUSH_ACK(tid=10)\n                           ---\u003e       acquires i_ceph_lock\n                                      cf-\u003etid(10) \u003c= flush_tid(10),\n                                      detaches cf from i_cap_flush_list\n                                      drops i_ceph_lock\n                                      ceph_free_cap_flush(cf) \u003c- frees it!\n  acquires i_ceph_lock     \u003c---\n  for-loop advances:\n    cf = list_next_entry(cf, i_list)\n      -- UAF on freed cf-\u003ei_list.next\n\nThe cf was just sent by __kick_flushing_caps itself via __send_cap().\nThe MDS may respond with FLUSH_ACK quickly enough that\nhandle_cap_flush_ack() frees cf before __kick_flushing_caps can\nfinish the iteration.\n\nFix by converting to a manual while loop: save the next pointer\nunder i_ceph_lock before dropping it, then use the saved pointer\nafter reacquiring, so the potentially-freed cf is never accessed again.","modified":"2026-09-14T05:26:59Z","published":"2026-09-11T20:19:51Z","upstream":["CVE-2026-89655"],"references":[{"type":"WEB","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-89655"}],"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-100904.json"}}],"schema_version":"1.9.0"}