[PATCH] qio: fix qemu crash when live migration

[yaozhenguo]

qemu will crash in live migration cleanup process at source host.
BT is as below:

0  0x00007f740fc9e165 in g_source_destroy () at /usr/lib64/libglib-2.0.so.0
1  0x000055a2982a0f6e in qio_net_listener_set_client_func_full
2  0x000055a298345130 in tcp_chr_update_read_handler
3  0x000055a298341598 in qemu_chr_fe_set_handlers_full
4  0x000055a298341655 in qemu_chr_fe_set_handlers
5  0x000055a298191e75 in vhost_user_blk_event
6  0x000055a298292b79 in object_deinit
7  object_finalize
8  object_unref
9  0x000055a298292b3c in object_property_del_all
10 object_finalize
11 object_unref
12 0x000055a298291d7d in object_property_del_child
13 object_unparent
14 0x000055a29834a3c4 in qemu_chr_cleanup
15 0x000055a298160d87 in qemu_cleanup
16 0x000055a297e6bff1 in main

Crash reason is that qio_net_listener_finalize is called before
qio_net_listener_set_client_func_full. so, listener->io_source
is used after free. fix this by adding more checks.

Signed-off-by: yaozhenguo <yaozhenguo@jd.com>
---
 io/net-listener.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/io/net-listener.c b/io/net-listener.c
index 47405965a6..c02965f919 100644
--- a/io/net-listener.c
+++ b/io/net-listener.c
@@ -143,6 +143,11 @@ void qio_net_listener_set_client_func_full(QIONetListener 
*listener,
 {
     size_t i;
 
+
+    if (!listener->nsioc || !listener->io_source || !listener->name) {
+        return;
+    }
+
     if (listener->io_notify) {
         listener->io_notify(listener->io_data);
     }
@@ -264,6 +269,10 @@ void qio_net_listener_disconnect(QIONetListener *listener)
 {
     size_t i;
 
+    if (!listener->nsioc || !listener->io_source || !listener->name) {
+        return;
+    }
+
     if (!listener->connected) {
         return;
     }
@@ -301,6 +310,10 @@ static void qio_net_listener_finalize(Object *obj)
     g_free(listener->io_source);
     g_free(listener->sioc);
     g_free(listener->name);
+
+    listener->io_source = NULL;
+    listener->sioc = NULL;
+    listener->name = NULL;
 }
 
 static const TypeInfo qio_net_listener_info = {
-- 
2.43.0