[PATCH] UBI: fix use after free in ubi_remove_volume()

[Wen Yang]

We can't use "vol" after it has been freed.

Fixes: 493cfaeaa0c9 ("mtd: utilize new cdev_device_add helper function")
Signed-off-by: Wen Yang <wenyang@xxxxxxxxxxxxxxxxx>
Cc: Richard Weinberger <richard@xxxxxx>
Cc: Miquel Raynal <miquel.raynal@xxxxxxxxxxx>
Cc: Vignesh Raghavendra <vigneshr@xxxxxx>
Cc: linux-mtd@xxxxxxxxxxxxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx
---
 drivers/mtd/ubi/vmt.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/mtd/ubi/vmt.c b/drivers/mtd/ubi/vmt.c
index 139ee13..8ff1478 100644
--- a/drivers/mtd/ubi/vmt.c
+++ b/drivers/mtd/ubi/vmt.c
@@ -375,7 +375,6 @@ int ubi_remove_volume(struct ubi_volume_desc *desc, int no_vtbl)
 	}
 
 	cdev_device_del(&vol->cdev, &vol->dev);
-	put_device(&vol->dev);
 
 	spin_lock(&ubi->volumes_lock);
 	ubi->rsvd_pebs -= reserved_pebs;
@@ -388,6 +387,8 @@ int ubi_remove_volume(struct ubi_volume_desc *desc, int no_vtbl)
 	if (!no_vtbl)
 		self_check_volumes(ubi);
 
+	put_device(&vol->dev);
+
 	return 0;
 
 out_err:
-- 
1.8.3.1