migration/multifd: fix memleaks in multifd_new_send_channel_async

When error happen in multifd_new_send_channel_async, 'sioc' will not be used
to create the multifd_send_thread. Let's free it to avoid a memleak. And also
do error_free after migrate_set_error() to avoid another leak in the same place.

The leak stack:
Direct leak of 2880 byte(s) in 8 object(s) allocated from:
    #0 0x7f20b5118ae8 in __interceptor_malloc (/lib64/libasan.so.5+0xefae8)
    #1 0x7f20b44df1d5 in g_malloc (/lib64/libglib-2.0.so.0+0x531d5)
    #2 0x564133bce18b in object_new_with_type /mnt/sdb/backup/qemu/qom/object.c:683
    #3 0x564133eea950 in qio_channel_socket_new /mnt/sdb/backup/qemu/io/channel-socket.c:56
    #4 0x5641339cfe4f in socket_send_channel_create /mnt/sdb/backup/qemu/migration/socket.c:37
    qemu#5 0x564133a10328 in multifd_save_setup /mnt/sdb/backup/qemu/migration/multifd.c:772
    qemu#6 0x5641339cebed in migrate_fd_connect /mnt/sdb/backup/qemu/migration/migration.c:3530
    qemu#7 0x5641339d15e4 in migration_channel_connect /mnt/sdb/backup/qemu/migration/channel.c:92
    qemu#8 0x5641339cf5b7 in socket_outgoing_migration /mnt/sdb/backup/qemu/migration/socket.c:108

Direct leak of 384 byte(s) in 8 object(s) allocated from:
    #0 0x7f20b5118cf0 in calloc (/lib64/libasan.so.5+0xefcf0)
    #1 0x7f20b44df22d in g_malloc0 (/lib64/libglib-2.0.so.0+0x5322d)
    #2 0x56413406fc17 in error_setv /mnt/sdb/backup/qemu/util/error.c:61
    #3 0x564134070464 in error_setg_errno_internal /mnt/sdb/backup/qemu/util/error.c:109
    #4 0x5641340851be in inet_connect_addr /mnt/sdb/backup/qemu/util/qemu-sockets.c:379
    qemu#5 0x5641340851be in inet_connect_saddr /mnt/sdb/backup/qemu/util/qemu-sockets.c:458
    qemu#6 0x5641340870ab in socket_connect /mnt/sdb/backup/qemu/util/qemu-sockets.c:1105
    qemu#7 0x564133eeaabf in qio_channel_socket_connect_sync /mnt/sdb/backup/qemu/io/channel-socket.c:145
    qemu#8 0x564133eeabf5 in qio_channel_socket_connect_worker /mnt/sdb/backup/qemu/io/channel-socket.c:168

Indirect leak of 360 byte(s) in 8 object(s) allocated from:
    #0 0x7f20b5118ae8 in __interceptor_malloc (/lib64/libasan.so.5+0xefae8)
    #1 0x7f20af901817 in __GI___vasprintf_chk (/lib64/libc.so.6+0x10d817)
    #2 0x7f20b451fa6c in g_vasprintf (/lib64/libglib-2.0.so.0+0x93a6c)
    #3 0x7f20b44f8cd0 in g_strdup_vprintf (/lib64/libglib-2.0.so.0+0x6ccd0)
    #4 0x7f20b44f8d8c in g_strdup_printf (/lib64/libglib-2.0.so.0+0x6cd8c)
    qemu#5 0x56413406fc86 in error_setv /mnt/sdb/backup/qemu/util/error.c:65
    qemu#6 0x564134070464 in error_setg_errno_internal /mnt/sdb/backup/qemu/util/error.c:109
    qemu#7 0x5641340851be in inet_connect_addr /mnt/sdb/backup/qemu/util/qemu-sockets.c:379
    qemu#8 0x5641340851be in inet_connect_saddr /mnt/sdb/backup/qemu/util/qemu-sockets.c:458
    qemu#9 0x5641340870ab in socket_connect /mnt/sdb/backup/qemu/util/qemu-sockets.c:1105
    qemu#10 0x564133eeaabf in qio_channel_socket_connect_sync /mnt/sdb/backup/qemu/io/channel-socket.c:145
    qemu#11 0x564133eeabf5 in qio_channel_socket_connect_worker /mnt/sdb/backup/qemu/io/channel-socket.c:168

Reported-by: Euler Robot <euler.robot@huawei.com>
Signed-off-by: Pan Nengyuan <pannengyuan@huawei.com>
Message-Id: <20200506095416.26099-2-pannengyuan@huawei.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

migration/multifd.c

@@ -727,6 +727,8 @@ static void multifd_new_send_channel_async(QIOTask *task, gpointer opaque)
          * its status.
          */
         p->quit = true;
+        object_unref(OBJECT(sioc));
+        error_free(local_err);
     } else {
         p->c = QIO_CHANNEL(sioc);
         qio_channel_set_delay(p->c, false);