[PATCH 4.4 015/146] mnt: fs_fully_visible test the proper mount for MNT_LOCKED

From: Greg Kroah-Hartman
Date: Mon Jul 25 2016 - 17:06:40 EST

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


From: Eric W. Biederman <ebiederm@xxxxxxxxxxxx>

commit d71ed6c930ac7d8f88f3cef6624a7e826392d61f upstream.

MNT_LOCKED implies on a child mount implies the child is locked to the
parent. So while looping through the children the children should be
tested (not their parent).

Typically an unshare of a mount namespace locks all mounts together
making both the parent and the slave as locked but there are a few
corner cases where other things work.

Fixes: ceeb0e5d39fc ("vfs: Ignore unlocked mounts in fs_fully_visible")
Reported-by: Seth Forshee <seth.forshee@xxxxxxxxxxxxx>
Signed-off-by: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

fs/namespace.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -3262,7 +3262,7 @@ static bool fs_fully_visible(struct file
list_for_each_entry(child, &mnt->mnt_mounts, mnt_child) {
struct inode *inode = child->mnt_mountpoint->d_inode;
/* Only worry about locked mounts */
- if (!(mnt_flags & MNT_LOCKED))
+ if (!(child->mnt.mnt_flags & MNT_LOCKED))
/* Is the directory permanetly empty? */
if (!is_empty_dir_inode(inode))