nbd: fix possible memory leak

commit ff6b8090 upstream.

we have already allocated memory for nbd_dev, but we were not
releasing that memory and just returning the error value.
Signed-off-by: Sudip Mukherjee <sudip@vectorindia.org>
Acked-by: Paul Clements <Paul.Clements@SteelEye.com>
Signed-off-by: Markus Pargmann <mpa@pengutronix.de>
Signed-off-by: Zefan Li <lizefan@huawei.com>

drivers/block/nbd.c

@@ -773,10 +773,6 @@ static int __init nbd_init(void)
 		return -EINVAL;
 	}
 
-	nbd_dev = kcalloc(nbds_max, sizeof(*nbd_dev), GFP_KERNEL);
-	if (!nbd_dev)
-		return -ENOMEM;
-
 	part_shift = 0;
 	if (max_part > 0) {
 		part_shift = fls(max_part);
@@ -798,6 +794,10 @@ static int __init nbd_init(void)
 	if (nbds_max > 1UL << (MINORBITS - part_shift))
 		return -EINVAL;
 
+	nbd_dev = kcalloc(nbds_max, sizeof(*nbd_dev), GFP_KERNEL);
+	if (!nbd_dev)
+		return -ENOMEM;
+
 	for (i = 0; i < nbds_max; i++) {
 		struct gendisk *disk = alloc_disk(1 << part_shift);
 		if (!disk)