Re: [syzbot] general protection fault in _wait_barrier

[Edward Adam Davis <eadavis@sina.com>]

From: Edward Aadm Davis <eadavis@sina.com>

#syz test: upstream 818bebeb63dd

diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
index f0646fb24371..8676b3bc463b 100644
--- a/drivers/md/raid1.c
+++ b/drivers/md/raid1.c
@@ -1692,11 +1692,34 @@ static bool raid1_make_request(struct mddev *mddev, struct bio *bio)
 	if (bio_data_dir(bio) == READ)
 		raid1_read_request(mddev, bio, sectors, NULL);
 	else {
+		int err;
+
 		md_write_start(mddev, bio);
-		if (!raid1_write_request(mddev, bio, sectors))
+		err = mddev_lock(mddev);
+
+		if (err < 0) {
+			md_write_end(mddev);
+			goto done;
+		}
+
+		if (!mddev->private) {
+			mddev_unlock(mddev);
+			md_write_end(mddev);
+			goto done;
+		}
+
+		err = raid1_write_request(mddev, bio, sectors);
+		mddev_unlock(mddev);
+
+		if (!err)
 			md_write_end(mddev);
 	}
+out:
 	return true;
+done:
+	bio->bi_status = BLK_STS_OFFLINE;
+	bio_endio(bio);
+	goto out;
 }
 
 static void raid1_status(struct seq_file *seq, struct mddev *mddev)