LOOKUP_MOUNTPOINT: we are cleaning "jumped" flag too late

commit 4f0ed93fb92d3528c73c80317509df3f800a222b upstream.

That (and traversals in case of umount .) should be done before
complete_walk().  Either a braino or mismerge damage on queue
reorders - either way, I should've spotted that much earlier.

Fucked-up-by: Al Viro <viro@zeniv.linux.org.uk>
X-Paperbag: Brown
Fixes: 161aff1d93ab "LOOKUP_MOUNTPOINT: fold path_mountpointat() into path_lookupat()"
Cc: stable@vger.kernel.org # v5.7+
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/fs/namei.c b/fs/namei.c
index 7af66d5..4c9d0c3 100644 (file)
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -2328,16 +2328,16 @@ static int path_lookupat(struct nameidata *nd, unsigned flags, struct path *path
        while (!(err = link_path_walk(s, nd)) &&
               (s = lookup_last(nd)) != NULL)
                ;
+       if (!err && unlikely(nd->flags & LOOKUP_MOUNTPOINT)) {
+               err = handle_lookup_down(nd);
+               nd->flags &= ~LOOKUP_JUMPED; // no d_weak_revalidate(), please...
+       }
        if (!err)
                err = complete_walk(nd);
 
        if (!err && nd->flags & LOOKUP_DIRECTORY)
                if (!d_can_lookup(nd->path.dentry))
                        err = -ENOTDIR;
-       if (!err && unlikely(nd->flags & LOOKUP_MOUNTPOINT)) {
-               err = handle_lookup_down(nd);
-               nd->flags &= ~LOOKUP_JUMPED; // no d_weak_revalidate(), please...
-       }
        if (!err) {
                *path = nd->path;
                nd->path.mnt = NULL;