This is a note to let you know that I've just added the patch titled
namespace: update event counter when umounting a deleted dentry
to the 4.6-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
namespace-update-event-counter-when-umounting-a-deleted-dentry.patch
and it can be found in the queue-4.6 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From e06b933e6ded42384164d28a2060b7f89243b895 Mon Sep 17 00:00:00 2001
From: Andrey Ulanov <andreyu@xxxxxxxxxx>
Date: Fri, 15 Apr 2016 14:24:41 -0700
Subject: namespace: update event counter when umounting a deleted dentry
From: Andrey Ulanov <andreyu@xxxxxxxxxx>
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 <andreyu@xxxxxxxxxx>
Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
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) {
Patches currently in stable-queue which might be from andreyu@xxxxxxxxxx are
queue-4.6/namespace-update-event-counter-when-umounting-a-deleted-dentry.patch
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