From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>

Fix outgoing migration which was crashing in
vmstate_hda_audio_stream_buf_needed, I think the problem
is that we have room for upto 4 streams in the array but only
use 2, when we come to try and save the state of the unused
streams we hit st->state == NULL.

Fixes: 280c1e1cdb24d80ecdfc
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Message-Id: <20180724102215.31866-1-dgilbert@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
---
 hw/audio/hda-codec.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/hw/audio/hda-codec.c b/hw/audio/hda-codec.c
index 2b58c3505b..617a1c1016 100644
--- a/hw/audio/hda-codec.c
+++ b/hw/audio/hda-codec.c
@@ -786,7 +786,7 @@ static void hda_audio_reset(DeviceState *dev)
 static bool vmstate_hda_audio_stream_buf_needed(void *opaque)
 {
     HDAAudioStream *st = opaque;
-    return st->state->use_timer;
+    return st->state && st->state->use_timer;
 }
 
 static const VMStateDescription vmstate_hda_audio_stream_buf = {
-- 
2.17.1