[PATCH 4.1 061/123] mnt: In detach_mounts detach the appropriate unmounted mount

From: Greg Kroah-Hartman
Date: Sat Aug 08 2015 - 18:31:03 EST

4.1-stable review patch. If anyone has any objections, please let me know.


From: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx>

commit fe78fcc85a2046c51f1535710996860557eeec20 upstream.

The handling of in detach_mounts of unmounted but connected mounts is
buggy and can lead to an infinite loop.

Correct the handling of unmounted mounts in detach_mount. When the
mountpoint of an unmounted but connected mount is connected to a
dentry, and that dentry is deleted we need to disconnect that mount
from the parent mount and the deleted dentry.

Nothing changes for the unmounted and connected children. They can be
safely ignored.

Fixes: ce07d891a0891d3c0d0c2d73d577490486b809e1 mnt: Honor MNT_LOCKED when detaching mounts
Signed-off-by: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

fs/namespace.c | 7 ++-----
1 file changed, 2 insertions(+), 5 deletions(-)

--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -1554,11 +1554,8 @@ void __detach_mounts(struct dentry *dent
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) {
- struct mount *p, *tmp;
- list_for_each_entry_safe(p, tmp, &mnt->mnt_mounts, mnt_child) {
- hlist_add_head(&p->mnt_umount.s_list, &unmounted);
- umount_mnt(p);
- }
+ hlist_add_head(&mnt->mnt_umount.s_list, &unmounted);
+ umount_mnt(mnt);
else umount_tree(mnt, UMOUNT_CONNECTED);

To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/