Merge tag 'v6.17.8' into linux-6.17.ylinux-6.17.y

This is the 6.17.8 stable release

1 files changed, 21 insertions, 1 deletions

diff --git a/fs/overlayfs/dir.c b/fs/overlayfs/dir.c
index dbd63a74df4b..039e829aa7de 100644
--- a/fs/overlayfs/dir.c
+++ b/fs/overlayfs/dir.c
@@ -205,12 +205,32 @@ struct dentry *ovl_create_real(struct ovl_fs *ofs, struct dentry *parent,
 			err = -EPERM;
 		}
 	}
-	if (!err && WARN_ON(!newdentry->d_inode)) {
+	if (err)
+		goto out;
+
+	if (WARN_ON(!newdentry->d_inode)) {
 		/*
 		 * Not quite sure if non-instantiated dentry is legal or not.
 		 * VFS doesn't seem to care so check and warn here.
 		 */
 		err = -EIO;
+	} else if (d_unhashed(newdentry)) {
+		struct dentry *d;
+		/*
+		 * Some filesystems (i.e. casefolded) may return an unhashed
+		 * negative dentry from the ovl_lookup_upper() call before
+		 * ovl_create_real().
+		 * In that case, lookup again after making the newdentry
+		 * positive, so ovl_create_upper() always returns a hashed
+		 * positive dentry.
+		 */
+		d = ovl_lookup_upper(ofs, newdentry->d_name.name, parent,
+				     newdentry->d_name.len);
+		dput(newdentry);
+		if (IS_ERR_OR_NULL(d))
+			err = d ? PTR_ERR(d) : -ENOENT;
+		else
+			return d;
 	}
 out:
 	if (err) {