Release buf on error path too.
Bug was introduced in 
b35ebdf076d697bc "migration: add postcopy
migration of dirty bitmaps" with the whole function.
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-Id: <
20180427142002.21930-3-vsementsov@virtuozzo.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
CC: qemu-stable@nongnu.org
Signed-off-by: Eric Blake <eblake@redhat.com>
 
         ret = qemu_get_buffer(f, buf, buf_size);
         if (ret != buf_size) {
             error_report("Failed to read bitmap bits");
+            g_free(buf);
             return -EIO;
         }