[PATCH] missing check in do_add_mount()

Make sure that we don't end up with symlink mounted over something

(mount --bind is safe since we use LOOKUP_FOLLOW in pathname resolution
there).

diff --git a/fs/namespace.c b/fs/namespace.c
index c2b8d730e6088b046e6c01bda2312b057ee32355..e29f147fa274c2d3c140d0070bfae95b7b4a3429 100644 (file)
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -681,6 +681,10 @@ static int do_add_mount(struct nameidata *nd, char *type, int flags,
        if (nd->mnt->mnt_sb == mnt->mnt_sb && nd->mnt->mnt_root == nd->dentry)
                goto unlock;
 
+       err = -EINVAL;
+       if (S_ISLNK(mnt->mnt_root->d_inode->i_mode))
+               goto unlock;
+
        mnt->mnt_flags = mnt_flags;
        err = graft_tree(mnt, nd);
 unlock: