From 7f053a6a745557b3f3ad63e9d28ba85c3c0b1563 Mon Sep 17 00:00:00 2001
From: Shaohua Li <shli@fb.com>
Date: Fri, 23 Jun 2017 09:19:49 -0700
Subject: [PATCH] MD: fix a null dereference

rdev->mddev could be null in start time.

Reported-by: Ming Lei <ming.lei@redhat.com>
Fix: 5a85071c2cbc(md: use a separate bio_set for synchronous IO.)
Cc: NeilBrown <neilb@suse.com>
Signed-off-by: Shaohua Li <shli@fb.com>
---
 drivers/md/md.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/md/md.c b/drivers/md/md.c
index 65ad837aeb54..092b48f8095e 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -205,7 +205,7 @@ EXPORT_SYMBOL_GPL(bio_alloc_mddev);
 
 static struct bio *md_bio_alloc_sync(struct mddev *mddev)
 {
-	if (!mddev->sync_set)
+	if (!mddev || !mddev->sync_set)
 		return bio_alloc(GFP_NOIO, 1);
 
 	return bio_alloc_bioset(GFP_NOIO, 1, mddev->sync_set);
-- 
2.20.1