monitor: move json init from OPEN event to init

At some point in the past, the OPEN event was changed to be issued from a
bottom half.  This creates a small window whereas a data callback registered in
init may be invoked before the OPEN event has been issued.

This is reproducible with:

 echo "{'execute': 'qmp_capabilities'}" | qemu-system-x86_64 -M none -qmp stdio

We can fix this for the monitor by moving the parser initialization to init.

The remaining state that is set in OPEN appears harmless.

Reported-by: Daniel Berrange <berrange@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>

1 files changed, 3 insertions, 1 deletions

diff --git a/monitor.c b/monitor.c
index 480f583f70..b188582057 100644
--- a/monitor.c
+++ b/monitor.c
@@ -4832,7 +4832,6 @@ static void monitor_control_event(void *opaque, int event)
     switch (event) {
     case CHR_EVENT_OPENED:
         mon->mc->command_mode = 0;
-        json_message_parser_init(&mon->mc->parser, handle_qmp_command);
         data = get_qmp_greeting();
         monitor_json_emitter(mon, data);
         qobject_decref(data);
@@ -4840,6 +4839,7 @@ static void monitor_control_event(void *opaque, int event)
         break;
     case CHR_EVENT_CLOSED:
         json_message_parser_destroy(&mon->mc->parser);
+        json_message_parser_init(&mon->mc->parser, handle_qmp_command);
         mon_refcount--;
         monitor_fdsets_cleanup();
         break;
@@ -4951,6 +4951,8 @@ void monitor_init(CharDriverState *chr, int flags)
                               monitor_event, mon);
     }
 
+    json_message_parser_init(&mon->mc->parser, handle_qmp_command);
+
     QLIST_INSERT_HEAD(&mon_list, mon, entry);
     if (!default_mon || (flags & MONITOR_IS_DEFAULT))
         default_mon = mon;