Merge remote-tracking branch 'remotes/kraxel/tags/pull-vnc-20141028-1' into staging

vnc: return directly if no vnc client connected
vnc: sanitize bits_per_pixel from the client (CVE-2014-7815)

# gpg: Signature made Tue 28 Oct 2014 10:52:31 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-20141028-1:
  vnc: return directly if no vnc client connected
  vnc: sanitize bits_per_pixel from the client
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>

ui/vnc.c

@@ -2026,6 +2026,16 @@ static void set_pixel_format(VncState *vs,
         return;
     }
 
+    switch (bits_per_pixel) {
+    case 8:
+    case 16:
+    case 32:
+        break;
+    default:
+        vnc_client_error(vs);
+        return;
+    }
+
     vs->client_pf.rmax = red_max;
     vs->client_pf.rbits = hweight_long(red_max);
     vs->client_pf.rshift = red_shift;
@@ -2768,6 +2778,11 @@ static void vnc_refresh(DisplayChangeListener *dcl)
     VncState *vs, *vn;
     int has_dirty, rects = 0;
 
+    if (QTAILQ_EMPTY(&vd->clients)) {
+        update_displaychangelistener(&vd->dcl, VNC_REFRESH_INTERVAL_MAX);
+        return;
+    }
+
     graphic_hw_update(NULL);
 
     if (vnc_trylock_display(vd)) {
@@ -2783,11 +2798,6 @@ static void vnc_refresh(DisplayChangeListener *dcl)
         /* vs might be free()ed here */
     }
 
-    if (QTAILQ_EMPTY(&vd->clients)) {
-        update_displaychangelistener(&vd->dcl, VNC_REFRESH_INTERVAL_MAX);
-        return;
-    }
-
     if (has_dirty && rects) {
         vd->dcl.update_interval /= 2;
         if (vd->dcl.update_interval < VNC_REFRESH_INTERVAL_BASE) {