From: Shaohua Li <shli@fb.com>
Date: Thu, 28 Jul 2016 16:06:34 +0000 (-0700)
Subject: MD: fix null pointer deference
X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=5d8817833c7609c24da9a92f71c53caa9c1424eb;p=linux-beck.git

MD: fix null pointer deference

The md device might not have personality (for example, ddf raid array). The
issue is introduced by 8430e7e0af9a15(md: disconnect device from personality
before trying to remove it)

Reported-by: kernel test robot <xiaolong.ye@intel.com>
Signed-off-by: Shaohua Li <shli@fb.com>
---

diff --git a/drivers/md/md.c b/drivers/md/md.c
index f77cad854044..c059f17b44d2 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -2595,8 +2595,10 @@ state_store(struct md_rdev *rdev, const char *buf, size_t len)
 		else
 			err = -EBUSY;
 	} else if (cmd_match(buf, "remove")) {
-		clear_bit(Blocked, &rdev->flags);
-		remove_and_add_spares(rdev->mddev, rdev);
+		if (rdev->mddev->pers) {
+			clear_bit(Blocked, &rdev->flags);
+			remove_and_add_spares(rdev->mddev, rdev);
+		}
 		if (rdev->raid_disk >= 0)
 			err = -EBUSY;
 		else {