CVE-2026-99226

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 lock(keyring name lock) down write(key->sem) load old keyring->user replace key->user and key->uid up write(key->sem) key put(key) key user put(old user): free read old user->uid read unlock(keyring name lock)

Chown neither takes keyring name lock nor key session mutex, so it can free the old account between the pointer load and the UID read. The lookup then reads freed memory even though the keyring itself is alive.

Use keyring->uid for the mapping check. key alloc() initializes this inline owner UID and keyctl chown key() updates it on chown. The existing name lock keeps its containing keyring allocated throughout the check, so lookup no longer depends on the account's lifetime. This also matches the owner UID used by the permission check.

KASAN report as below:

BUG: KASAN: slab-use-after-free in find keyring by name+0x577/0x5d0 Read of size 4 at addr ffff8881128ae2ec by task keycase/500