qemu: cgroup: Fix crash if starting nographics guest

We can dereference graphics[0] even if guest has no graphics device
configured. I screwed this up in a216e6487255d3b65d97c7ec1fa5da63dbced902

https://bugzilla.redhat.com/show_bug.cgi?id=1014088

diff --git a/src/qemu/qemu_cgroup.c b/src/qemu/qemu_cgroup.c
index f95c7f2e678f0bc090aa765480c41fa5fa87ce04..ace7e3573a25b2e8c4a1ebbb064a9fe4f033dbc9 100644 (file)
--- a/src/qemu/qemu_cgroup.c
+++ b/src/qemu/qemu_cgroup.c
@@ -490,9 +490,10 @@ qemuSetupDevicesCgroup(virQEMUDriverPtr driver,
 
     if (vm->def->nsounds &&
         ((!vm->def->ngraphics && cfg->nogfxAllowHostAudio) ||
-         ((vm->def->graphics[0]->type == VIR_DOMAIN_GRAPHICS_TYPE_VNC &&
+         (vm->def->graphics &&
+          ((vm->def->graphics[0]->type == VIR_DOMAIN_GRAPHICS_TYPE_VNC &&
            cfg->vncAllowHostAudio) ||
-           (vm->def->graphics[0]->type == VIR_DOMAIN_GRAPHICS_TYPE_SDL)))) {
+           (vm->def->graphics[0]->type == VIR_DOMAIN_GRAPHICS_TYPE_SDL))))) {
         rv = virCgroupAllowDeviceMajor(priv->cgroup, 'c', DEVICE_SND_MAJOR,
                                        VIR_CGROUP_DEVICE_RW);
         virDomainAuditCgroupMajor(vm, priv->cgroup, "allow", DEVICE_SND_MAJOR,