[aandrejevic] 67476: [NTVDM] Also check for BlockData == 0 in RosResizeMemory. This, however, wasn't a crash since we were lucky enough to cast the segment to a WORD before the access.

Author: aandrejevic
Date: Wed Apr 29 00:58:22 2015
New Revision: 67476

URL: http://svn.reactos.org/svn/reactos?rev=67476&view=rev
Log:
[NTVDM]
Also check for BlockData == 0 in RosResizeMemory. This, however, wasn't a crash since
we
were lucky enough to cast the segment to a WORD before the access.


Modified:
    trunk/reactos/subsystems/mvdm/ntvdm/dos/dos32krnl/memory.c

Modified: trunk/reactos/subsystems/mvdm/ntvdm/dos/dos32krnl/memory.c
URL:
http://svn.reactos.org/svn/reactos/trunk/reactos/subsystems/mvdm/ntvdm/dos/…
==============================================================================
--- trunk/reactos/subsystems/mvdm/ntvdm/dos/dos32krnl/memory.c	[iso-8859-1] (original)
+++ trunk/reactos/subsystems/mvdm/ntvdm/dos/dos32krnl/memory.c	[iso-8859-1] Wed Apr 29
00:58:22 2015
@@ -210,7 +210,9 @@
            NewSize);
 
     /* Make sure this is a valid, allocated block */
-    if ((Mcb->BlockType != 'M' && Mcb->BlockType != 'Z') ||
Mcb->OwnerPsp == 0)
+    if (BlockData == 0
+        || (Mcb->BlockType != 'M' && Mcb->BlockType !=
'Z')
+        || Mcb->OwnerPsp == 0)
     {
         Success = FALSE;
         DosLastError = ERROR_INVALID_HANDLE;