Patchwork [29/43] qom: dynamic_cast of NULL is always NULL

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Submitter Michael Roth
Date Dec. 3, 2012, 10:25 p.m.
Message ID <1354573559-26274-2-git-send-email-mdroth@linux.vnet.ibm.com>
Download mbox | patch
Permalink /patch/203464/
State New
Headers show

Comments

Michael Roth - Dec. 3, 2012, 10:25 p.m.
From: Paolo Bonzini <pbonzini@redhat.com>

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 <armbru@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
(cherry picked from commit b7f43fe46029d8fd0594cd599fa2599dcce0f553)

Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
---
 qom/object.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

Patch

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();