[PATCH 4/7] hw/audio/asc: fix SIGSEGV in asc_realize()

["Volker Rümelin" <vr_qemu@t-online.de>]

AUD_open_out() may fail and return NULL. This may then lead to
a segmentation fault in memset() below. The memset() behaviour
is undefined if the pointer to the destination object is a null
pointer.

Add the missing error handling code.

Signed-off-by: Volker Rümelin <vr_qemu@t-online.de>
---
 hw/audio/asc.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/hw/audio/asc.c b/hw/audio/asc.c
index 18382ccf6a..03dee0fcc7 100644
--- a/hw/audio/asc.c
+++ b/hw/audio/asc.c
@@ -12,6 +12,7 @@
 
 #include "qemu/osdep.h"
 #include "qemu/timer.h"
+#include "qapi/error.h"
 #include "hw/sysbus.h"
 #include "hw/irq.h"
 #include "audio/audio.h"
@@ -653,6 +654,12 @@ static void asc_realize(DeviceState *dev, Error **errp)
 
     s->voice = AUD_open_out(&s->card, s->voice, "asc.out", s, asc_out_cb,
                             &as);
+    if (!s->voice) {
+        asc_unrealize(dev);
+        error_setg(errp, "Initializing audio stream failed");
+        return;
+    }
+
     s->shift = 1;
     s->samples = AUD_get_buffer_size_out(s->voice) >> s->shift;
     s->mixbuf = g_malloc0(s->samples << s->shift);
-- 
2.43.0