mtd: rfd_ftl: fix use-after-free

del_mtd_blktrans_dev() will kfree part, so after this call both part and
dev point to freed memory. Move the call to avoid use-after-free.
Signed-off-by: Sean Young <sean@mess.org>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20210807214538.14484-5-sean@mess.org

drivers/mtd/rfd_ftl.c

@@ -800,10 +800,10 @@ static void rfd_ftl_remove_dev(struct mtd_blktrans_dev *dev)
 			part->mbd.mtd->name, i, part->blocks[i].erases);
 	}
 
-	del_mtd_blktrans_dev(dev);
 	vfree(part->sector_map);
 	kfree(part->header_cache);
 	kfree(part->blocks);
+	del_mtd_blktrans_dev(dev);
 }
 
 static struct mtd_blktrans_ops rfd_ftl_tr = {