[ros-diffs] [tfaber] 66243: [WIN32K:NTUSER] - Assert sanity of object reference counts in UserReferenceObject, UserDereferenceObject and UserDeleteObject. If you hit a cLockObj < 0x10000 assertion failure, you...

Author: tfaber
Date: Fri Feb 13 10:11:50 2015
New Revision: 66243

URL: http://svn.reactos.org/svn/reactos?rev=66243&view=rev
Log:
[WIN32K:NTUSER]
- Assert sanity of object reference counts in UserReferenceObject, UserDereferenceObject
and UserDeleteObject. If you hit a cLockObj < 0x10000 assertion failure, you found
yourself a use after free (RtlFreeHeap will put a LIST_ENTRY in this location, so a freed
item has a kernel pointer there).
See CORE-8703 for an example.

Modified:
    trunk/reactos/win32ss/user/ntuser/object.c

Modified: trunk/reactos/win32ss/user/ntuser/object.c
URL:
http://svn.reactos.org/svn/reactos/trunk/reactos/win32ss/user/ntuser/object…
==============================================================================
--- trunk/reactos/win32ss/user/ntuser/object.c	[iso-8859-1] (original)
+++ trunk/reactos/win32ss/user/ntuser/object.c	[iso-8859-1] Fri Feb 13 10:11:50 2015
@@ -586,9 +586,10 @@
 FASTCALL
 UserDereferenceObject(PVOID Object)
 {
-    PHEAD ObjHead = (PHEAD)Object;
+    PHEAD ObjHead = Object;
 
     ASSERT(ObjHead->cLockObj >= 1);
+    ASSERT(ObjHead->cLockObj < 0x10000);
 
     if (--ObjHead->cLockObj == 0)
     {
@@ -663,6 +664,7 @@
    if (!body) return FALSE;
 
    ASSERT( ((PHEAD)body)->cLockObj >= 1);
+   ASSERT( ((PHEAD)body)->cLockObj < 0x10000);
 
    return UserFreeHandle(gHandleTable, h);
 }
@@ -671,9 +673,11 @@
 FASTCALL
 UserReferenceObject(PVOID obj)
 {
-   ASSERT(((PHEAD)obj)->cLockObj >= 0);
-
-   ((PHEAD)obj)->cLockObj++;
+   PHEAD ObjHead = obj;
+   ASSERT(ObjHead->cLockObj >= 0);
+   ASSERT(ObjHead->cLockObj < 0x10000);
+
+   ObjHead->cLockObj++;
 }
 
 PVOID