4.4-stable review patch. If anyone has any objections, please let me know.
------------------ From: Andrey Ulanov <[email protected]> commit e06b933e6ded42384164d28a2060b7f89243b895 upstream. - m_start() in fs/namespace.c expects that ns->event is incremented each time a mount added or removed from ns->list. - umount_tree() removes items from the list but does not increment event counter, expecting that it's done before the function is called. - There are some codepaths that call umount_tree() without updating "event" counter. e.g. from __detach_mounts(). - When this happens m_start may reuse a cached mount structure that no longer belongs to ns->list (i.e. use after free which usually leads to infinite loop). This change fixes the above problem by incrementing global event counter before invoking umount_tree(). Change-Id: I622c8e84dcb9fb63542372c5dbf0178ee86bb589 Signed-off-by: Andrey Ulanov <[email protected]> Signed-off-by: Al Viro <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]> --- fs/namespace.c | 1 + 1 file changed, 1 insertion(+) --- a/fs/namespace.c +++ b/fs/namespace.c @@ -1562,6 +1562,7 @@ void __detach_mounts(struct dentry *dent goto out_unlock; lock_mount_hash(); + event++; while (!hlist_empty(&mp->m_list)) { mnt = hlist_entry(mp->m_list.first, struct mount, mnt_mp_list); if (mnt->mnt.mnt_flags & MNT_UMOUNT) {
