[aandrejevic] 67707: [NTVDM] Fill the part of the buffer that was supposed to receive memory data above the MAX_ADDRESS with 0xFF.

Author: aandrejevic
Date: Wed May 13 23:23:17 2015
New Revision: 67707

URL: http://svn.reactos.org/svn/reactos?rev=67707&view=rev
Log:
[NTVDM]
Fill the part of the buffer that was supposed to receive memory data
above the MAX_ADDRESS with 0xFF.

Modified:
    trunk/reactos/subsystems/mvdm/ntvdm/emulator.c

Modified: trunk/reactos/subsystems/mvdm/ntvdm/emulator.c
URL: http://svn.reactos.org/svn/reactos/trunk/reactos/subsystems/mvdm/ntvdm/emula...
==============================================================================
--- trunk/reactos/subsystems/mvdm/ntvdm/emulator.c	[iso-8859-1] (original)
+++ trunk/reactos/subsystems/mvdm/ntvdm/emulator.c	[iso-8859-1] Wed May 13 23:23:17 2015
@@ -73,8 +73,16 @@
     /* If the A20 line is disabled, mask bit 20 */
     if (!A20Line) Address &= ~(1 << 20);

-    if (Address >= MAX_ADDRESS) return;
-    Size = min(Size, MAX_ADDRESS - Address);
+    if ((Address + Size - 1) >= MAX_ADDRESS)
+    {
+        ULONG ExtraStart = (Address < MAX_ADDRESS) ? MAX_ADDRESS - Address : 0;
+
+        /* Fill the memory that was above the limit with 0xFF */
+        RtlFillMemory((PVOID)((ULONG_PTR)Buffer + ExtraStart), Size - ExtraStart, 0xFF);
+
+        if (Address < MAX_ADDRESS) Size = MAX_ADDRESS - Address;
+        else return;
+    }

/* Read while calling fast memory hooks */
     MemRead(Address, Buffer, Size);