audio/hda: fix guest triggerable assert

Guest writes to a readonly register trigger the assert in
intel_hda_reg_write().  Add a check and just ignore them.

Buglink: https://bugzilla.redhat.com/show_bug.cgi?id=1628433
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-id: 20181123063957.9515-1-kraxel@redhat.com

diff --git a/hw/audio/intel-hda.c b/hw/audio/intel-hda.c
index 23a2cf6..33e333c 100644 (file)
--- a/hw/audio/intel-hda.c
+++ b/hw/audio/intel-hda.c
@@ -23,6 +23,7 @@
 #include "hw/pci/msi.h"
 #include "qemu/timer.h"
 #include "qemu/bitops.h"
+#include "qemu/log.h"
 #include "hw/audio/soundhw.h"
 #include "intel-hda.h"
 #include "intel-hda-defs.h"
@@ -929,6 +930,11 @@ static void intel_hda_reg_write(IntelHDAState *d, const IntelHDAReg *reg, uint32
     if (!reg) {
         return;
     }
+    if (!reg->wmask) {
+        qemu_log_mask(LOG_GUEST_ERROR, "intel-hda: write to r/o reg %s\n",
+                      reg->name);
+        return;
+    }
 
     if (d->debug) {
         time_t now = time(NULL);