In the Linux kernel, the following vulnerability has been resolved: keys: Avoid the owner account dereference in named keyring lookup Named keyring lookup must keep the storage containing the owner UID alive through the namespace mapping check. find_keyring_by_name() reads keyring->user->uid under keyring_name_lock, but that lock protects the keyring's name entry and allocation, not its separate key_user. A named session-keyring join can overlap a privileged KEYCTL_CHOWN on another CPU. If the keyring holds the last reference to its old dynamic key_user and the ownership transfer succeeds, the following ordering is possible: Named join Chown find_keyring_by_name() keyctl_chown_key() read_loc