CVE-2026-89655CVE-2026-89655

In the Linux kernel, the following vulnerability has been resolved: ceph: fix UAF in __kick_flushing_caps() on cf entry freed during unlock list_for_each_entry() iterates ci->i_cap_flush_list but drops i_ceph_lock to send cap messages. During the unlock window, handle_cap_flush_ack() can acquire i_ceph_lock, detach cf entries with tid <= flush_tid from the list, release i_ceph_lock, and free them via ceph_free_cap_flush() outside any lock. When the original thread reacquires i_ceph_lock and the for-loop macro advances via cf = list_next_entry(cf, i_list), it dereferences cf->i_list.next on freed memory. The race timeline: __kick_flushing_caps() handle_cap_flush_ack() ----------------------- ----------------------- holds i_ceph_lock <--- iterates to cf (tid=10) prepares FLUSH message drops i_ceph_lock <--- __send_cap() ── FLUSH(tid=10) MDS sends FLUSH_ACK(tid=10) --->