[Qemu-stable] [PATCH 25/56] qom: Fix class cast of NULL classes

[Michael Roth]

From: Peter Crosthwaite <address@hidden>

Its clear from the implementation that class casting is supposed to work
with a NULL class argument. Guard all dereferences of the class argument
against NULL accordingly.

Signed-off-by: Peter Crosthwaite <address@hidden>
Message-id: address@hidden
Signed-off-by: Anthony Liguori <address@hidden>
(cherry picked from commit 9d6a3d58e4d1431ab3809ff621cfd1f9ec75eef5)

Signed-off-by: Michael Roth <address@hidden>
---
 qom/object.c |    6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/qom/object.c b/qom/object.c
index 803b94b..b7ecb9f 100644
--- a/qom/object.c
+++ b/qom/object.c
@@ -531,14 +531,14 @@ ObjectClass *object_class_dynamic_cast_assert(ObjectClass 
*class,
 #ifdef CONFIG_QOM_CAST_DEBUG
     int i;
 
-    for (i = 0; i < OBJECT_CLASS_CAST_CACHE; i++) {
+    for (i = 0; class && i < OBJECT_CLASS_CAST_CACHE; i++) {
         if (class->cast_cache[i] == typename) {
             ret = class;
             goto out;
         }
     }
 #else
-    if (!class->interfaces) {
+    if (!class || !class->interfaces) {
         return class;
     }
 #endif
@@ -551,7 +551,7 @@ ObjectClass *object_class_dynamic_cast_assert(ObjectClass 
*class,
     }
 
 #ifdef CONFIG_QOM_CAST_DEBUG
-    if (ret == class) {
+    if (class && ret == class) {
         for (i = 1; i < OBJECT_CLASS_CAST_CACHE; i++) {
             class->cast_cache[i - 1] = class->cast_cache[i];
         }
-- 
1.7.9.5