blk->name isn't an array, but a pointer that can be NULL. Checking for
an anonymous BB must involve a NULL check first, otherwise we get
crashes.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Fam Zheng <famz@redhat.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Jeff Cody <jcody@redhat.com>
---
 block/block-backend.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/block/block-backend.c b/block/block-backend.c
index f3a6008..7d7f369 100644
--- a/block/block-backend.c
+++ b/block/block-backend.c
@@ -168,7 +168,7 @@ static int blk_root_inactivate(BdrvChild *child)
      * this point because the VM is stopped) and unattached monitor-owned
      * BlockBackends. If there is still any other user like a block job, then
      * we simply can't inactivate the image. */
-    if (!blk->dev && !blk->name[0]) {
+    if (!blk->dev && !blk_name(blk)[0]) {
         return -EPERM;
     }
 
-- 
1.8.3.1