From e06b933e6ded42384164d28a2060b7f89243b895 Mon Sep 17 00:00:00 2001 From: Andrey Ulanov Date: Fri, 15 Apr 2016 14:24:41 -0700 Subject: [PATCH] namespace: update event counter when umounting a deleted dentry - 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 Cc: stable@vger.kernel.org Signed-off-by: Andrey Ulanov Signed-off-by: Al Viro --- fs/namespace.c | 1 + 1 file changed, 1 insertion(+) diff --git a/fs/namespace.c b/fs/namespace.c index 4fb1691b4355..298618b88bba 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -1562,6 +1562,7 @@ void __detach_mounts(struct dentry *dentry) 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) {