Patch "vfs: Ignore unlocked mounts in fs_fully_visible" has been added to the 4.1-stable tree

This is a note to let you know that I've just added the patch titled

vfs: Ignore unlocked mounts in fs_fully_visible

to the 4.1-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:
vfs-ignore-unlocked-mounts-in-fs_fully_visible.patch
and it can be found in the queue-4.1 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: "Eric W. Biederman" <[email protected]>
Date: Wed, 7 Jan 2015 08:10:09 -0600
Subject: vfs: Ignore unlocked mounts in fs_fully_visible

From: "Eric W. Biederman" <[email protected]>

commit ceeb0e5d39fcdf4dca2c997bf225c7fc49200b37 upstream.

Limit the mounts fs_fully_visible considers to locked mounts. Unlocked can always be unmounted so considering them adds hassle but no security benefit.

---
 fs/namespace.c |    8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

@@ -3185,11 +3185,15 @@ bool fs_fully_visible(struct file_system
 		if (mnt->mnt.mnt_root != mnt->mnt.mnt_sb->s_root)
 			continue;
 
-		/* This mount is not fully visible if there are any child mounts
-		 * that cover anything except for empty directories.
+		/* This mount is not fully visible if there are any
+		 * locked child mounts that cover anything except for
+		 * empty directories.
 		 */
 		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->mnt.mnt_flags & MNT_LOCKED))
+				continue;
 			if (!S_ISDIR(inode->i_mode))
 				goto next;
 			if (inode->i_nlink > 2)

Patches currently in stable-queue which might be from [email protected] are

queue-4.1/vfs-ignore-unlocked-mounts-in-fs_fully_visible.patch queue-4.1/vfs-remove-incorrect-debugging-warn-in-prepend_path.patch