vnc: fix possible uninitialized removals

Some VncState values are not initialized before the Websocket handshake.
If it fails QEMU segfaults during the cleanup. To prevent this behavior
intialization checks are added.

Signed-off-by: Tim Hardeck <thardeck@suse.de>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>

2 files changed, 9 insertions, 3 deletions

diff --git a/ui/vnc.c b/ui/vnc.c
index ee08894f7f..ff4e2ae586 100644
--- a/ui/vnc.c
+++ b/ui/vnc.c
@@ -1053,20 +1053,24 @@ void vnc_disconnect_finish(VncState *vs)
     audio_del(vs);
     vnc_release_modifiers(vs);
 
-    QTAILQ_REMOVE(&vs->vd->clients, vs, next);
+    if (vs->initialized) {
+        QTAILQ_REMOVE(&vs->vd->clients, vs, next);
+        qemu_remove_mouse_mode_change_notifier(&vs->mouse_mode_notifier);
+    }
 
     if (QTAILQ_EMPTY(&vs->vd->clients)) {
         dcl->idle = 1;
     }
 
-    qemu_remove_mouse_mode_change_notifier(&vs->mouse_mode_notifier);
     vnc_remove_timer(vs->vd);
     if (vs->vd->lock_key_sync)
         qemu_remove_led_event_handler(vs->led);
     vnc_unlock_output(vs);
 
     qemu_mutex_destroy(&vs->output_mutex);
-    qemu_bh_delete(vs->bh);
+    if (vs->bh != NULL) {
+        qemu_bh_delete(vs->bh);
+    }
     buffer_free(&vs->jobs_buffer);
 
     for (i = 0; i < VNC_STAT_ROWS; ++i) {
@@ -2749,6 +2753,7 @@ static void vnc_connect(VncDisplay *vd, int csock, int skipauth, bool websocket)
 
 void vnc_init_state(VncState *vs)
 {
+    vs->initialized = true;
     VncDisplay *vd = vs->vd;
 
     vs->ds = vd->ds;
diff --git a/ui/vnc.h b/ui/vnc.h
index f93c89a2f7..45d7686843 100644
--- a/ui/vnc.h
+++ b/ui/vnc.h
@@ -306,6 +306,7 @@ struct VncState
     QEMUPutLEDEntry *led;
 
     bool abort;
+    bool initialized;
     QemuMutex output_mutex;
     QEMUBH *bh;
     Buffer jobs_buffer;