diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
index f0646fb24371..d35efa876274 100644
--- a/drivers/md/raid1.c
+++ b/drivers/md/raid1.c
@@ -3050,6 +3050,11 @@ static struct r1conf *setup_conf(struct mddev *mddev)
  struct md_rdev *rdev;
  size_t r1bio_size;
  int err = -ENOMEM;
+
+        /* check if mddev->raid_disks is valid before passsing through