eCryptfs: use after free in ecryptfs_release_messaging()

commit db86be3a12d0b6e5c5b51c2ab2a48f06329cb590 upstream.

We're freeing the list iterator so we should be using the _safe()
version of hlist_for_each_entry().

Fixes: 88b4a07e ("[PATCH] eCryptfs: Public key transport mechanism")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Tyler Hicks <tyhicks@canonical.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>