From 1f9db2243c1b987c834fe559a8e73b3178f50c2b Mon Sep 17 00:00:00 2001
From: Peter Lieven <pl@kamp.de>
Date: Tue, 24 Sep 2013 15:35:09 +0200
Subject: [PATCH] block/get_block_status: avoid segfault if there is no
 backing_hd

Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Peter Lieven <pl@kamp.de>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 block.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/block.c b/block.c
index 9b444b3443..3366017aea 100644
--- a/block.c
+++ b/block.c
@@ -3169,7 +3169,7 @@ static int64_t coroutine_fn bdrv_co_get_block_status(BlockDriverState *bs,
     if (!(ret & BDRV_BLOCK_DATA)) {
         if (bdrv_has_zero_init(bs)) {
             ret |= BDRV_BLOCK_ZERO;
-        } else {
+        } else if (bs->backing_hd) {
             BlockDriverState *bs2 = bs->backing_hd;
             int64_t length2 = bdrv_getlength(bs2);
             if (length2 >= 0 && sector_num >= (length2 >> BDRV_SECTOR_BITS)) {