[PATCH 5.11 028/210] LOOKUP_MOUNTPOINT: we are cleaning "jumped" flag too late

Greg Kroah-Hartman
2021-04-12T09:22:12Z

From: Al Viro <viro@zeniv.linux.org.uk>

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>
---
fs/namei.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)

--- a/fs/namei.c
+++ b/fs/namei.c
@@ -2330,16 +2330,16 @@ static int path_lookupat(struct nameidat
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;