From: Aleksandar Andrejevic <aandrejevic@reactos.org>
Date: Wed, 29 Apr 2015 00:58:22 +0000 (+0000)
Subject: [NTVDM]
X-Git-Tag: backups/colins-printing-for-freedom@73041~141
X-Git-Url: https://git.reactos.org/?p=reactos.git;a=commitdiff_plain;h=eba20f3ad83b98015bdfb03f976bf88138d35b6b;ds=sidebyside

[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.


svn path=/trunk/; revision=67476
---

diff --git a/reactos/subsystems/mvdm/ntvdm/dos/dos32krnl/memory.c b/reactos/subsystems/mvdm/ntvdm/dos/dos32krnl/memory.c
index 892bbbd3ffd..4a96255724d 100644
--- a/reactos/subsystems/mvdm/ntvdm/dos/dos32krnl/memory.c
+++ b/reactos/subsystems/mvdm/ntvdm/dos/dos32krnl/memory.c
@@ -210,7 +210,9 @@ BOOLEAN DosResizeMemory(WORD BlockData, WORD NewSize, WORD *MaxAvailable)
            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;