[PATCH] qom: fix NULL pointer in object_initialize_with_type()

[alexjlzheng]

From: Jinliang Zheng <alexjlzheng@tencent.com>

Currently, object_initialize_with_type() calls object_class_property_init_all()
before initializing Object->properties. This may cause Object->properties to
still be NULL when we call object_property_add() on Object.

For exmaple, if we extend DEFINE_PROP_ARRAY() to a version with a default value
other than 0:
        #define DEFINE_PROP_ARRAY_EXAMPLE(_name, _state, _field,        \
                                _arrayfield, _arrayprop, _arraytype)    \
                DEFINE_PROP((PROP_ARRAY_LEN_PREFIX _name),              \
                        _state, _field, qdev_prop_arraylen_virtio_net,  \
                        uint32_t,                                       \
                        .set_default = true,                            \
                        .defval.u = <non-zero>,                         \
                        .arrayinfo = &(_arrayprop),                     \
                        .arrayfieldsize = sizeof(_arraytype),           \
                        .arrayoffset = offsetof(_state, _arrayfield))
We should have:
        object_initialize_with_type
          object_class_property_init_all
            ObjectProperty->init() / object_property_init_defval
              ...
                set_prop_arraylen
                  object_property_add
                    object_property_try_add
                      g_hash_table_insert(Object->properties)   <- NULL
          obj->properties = g_hash_table_new_full()             <- initializing

This patch fixes the above problem by exchanging the order of Ojbect->properties
initialization and object_class_property_init_all().

Signed-off-by: Jinliang Zheng <alexjlzheng@tencent.com>
---
 qom/object.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/qom/object.c b/qom/object.c
index 157a45c5f8..734b52f048 100644
--- a/qom/object.c
+++ b/qom/object.c
@@ -556,9 +556,9 @@ static void object_initialize_with_type(Object *obj, size_t 
size, TypeImpl *type
     memset(obj, 0, type->instance_size);
     obj->class = type->class;
     object_ref(obj);
-    object_class_property_init_all(obj);
     obj->properties = g_hash_table_new_full(g_str_hash, g_str_equal,
                                             NULL, object_property_free);
+    object_class_property_init_all(obj);
     object_init_with_type(obj, type);
     object_post_init_with_type(obj, type);
 }
-- 
2.41.1