[PATCH 4.4 45/50] ovl: fix getcwd() failure after unsuccessful rmdir

[Greg Kroah-Hartman]

4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Rui Wang <rui.y.wang@xxxxxxxxx>

commit ce9113bbcbf45a57c082d6603b9a9f342be3ef74 upstream.

ovl_remove_upper() should do d_drop() only after it successfully
removes the dir, otherwise a subsequent getcwd() system call will
fail, breaking userspace programs.

This is to fix: https://bugzilla.kernel.org/show_bug.cgi?id=110491

Signed-off-by: Rui Wang <rui.y.wang@xxxxxxxxx>
Reviewed-by: Konstantin Khlebnikov <koct9i@xxxxxxxxx>
Signed-off-by: Miklos Szeredi <miklos@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>


---
 fs/overlayfs/dir.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/fs/overlayfs/dir.c
+++ b/fs/overlayfs/dir.c
@@ -618,7 +618,8 @@ static int ovl_remove_upper(struct dentr
 	 * sole user of this dentry.  Too tricky...  Just unhash for
 	 * now.
 	 */
-	d_drop(dentry);
+	if (!err)
+		d_drop(dentry);
 	mutex_unlock(&dir->i_mutex);
 
 	return err;