vfs: Ignore unlocked mounts in fs_fully_visible
Limit the mounts fs_fully_visible considers to locked mounts.
Unlocked can always be unmounted so considering them adds hassle
but no security benefit.
Cc: stable@vger.kernel.org
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
diff --git a/fs/namespace.c b/fs/namespace.c
index 63b9806..8c7b8e0 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -3205,11 +3205,15 @@
((mnt->mnt.mnt_flags & MNT_ATIME_MASK) != (new_flags & MNT_ATIME_MASK)))
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)