int install_process_keyring_to_cred(struct cred *new)
{
	struct key *keyring;

	if (new->process_keyring)
		return -EEXIST;

	keyring = keyring_alloc("_pid", new->uid, new->gid, new,
				KEY_POS_ALL | KEY_USR_VIEW,
				KEY_ALLOC_QUOTA_OVERRUN, NULL);
	if (IS_ERR(keyring))
		return PTR_ERR(keyring);

	new->process_keyring = keyring;
	return 0;
}

The product contains a concurrent code sequence that requires temporary, exclusive access to a shared resource, but a timing window exists in which the shared resource can be modified by another code sequence operating concurrently.