Merge remote-tracking branch 'remotes/kraxel/tags/pull-vnc-20151126-1…

…' into staging

vnc: fix segfault

# gpg: Signature made Thu 26 Nov 2015 07:37:43 GMT using RSA key ID D3E87138
# gpg: Good signature from "Gerd Hoffmann (work) <kraxel@redhat.com>"
# gpg:                 aka "Gerd Hoffmann <gerd@kraxel.org>"
# gpg:                 aka "Gerd Hoffmann (private) <kraxel@gmail.com>"

* remotes/kraxel/tags/pull-vnc-20151126-1:
  vnc: fix segfault

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

ui/vnc.c

@@ -931,6 +931,11 @@ static void vnc_dpy_copy(DisplayChangeListener *dcl,
     int i, x, y, pitch, inc, w_lim, s;
     int cmp_bytes;
 
+    if (!vd->server) {
+        /* no client connected */
+        return;
+    }
+
     vnc_refresh_server_surface(vd);
     QTAILQ_FOREACH_SAFE(vs, &vd->clients, next, vn) {
         if (vnc_has_feature(vs, VNC_FEATURE_COPYRECT)) {