[Qemu-devel] [PATCH 29/43] qom: dynamic_cast of NULL is always NULL

[Michael Roth]

From: Paolo Bonzini <address@hidden>

Trying to cast a NULL value will cause a crash.  Returning
NULL is also sensible, and it is also what the type-unsafe
DO_UPCAST macro does.

Reported-by: Markus Armbruster <address@hidden>
Signed-off-by: Paolo Bonzini <address@hidden>
Signed-off-by: Anthony Liguori <address@hidden>
(cherry picked from commit b7f43fe46029d8fd0594cd599fa2599dcce0f553)

Signed-off-by: Michael Roth <address@hidden>
---
 qom/object.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/qom/object.c b/qom/object.c
index e3e9242..f33e84d 100644
--- a/qom/object.c
+++ b/qom/object.c
@@ -417,7 +417,7 @@ void object_delete(Object *obj)
 
 Object *object_dynamic_cast(Object *obj, const char *typename)
 {
-    if (object_class_dynamic_cast(object_get_class(obj), typename)) {
+    if (obj && object_class_dynamic_cast(object_get_class(obj), typename)) {
         return obj;
     }
 
@@ -430,7 +430,7 @@ Object *object_dynamic_cast_assert(Object *obj, const char 
*typename)
 
     inst = object_dynamic_cast(obj, typename);
 
-    if (!inst) {
+    if (!inst && obj) {
         fprintf(stderr, "Object %p is not an instance of type %s\n",
                 obj, typename);
         abort();
-- 
1.7.9.5