[hbelusca] 70424: [NTVDM]: Cast all the number-of-sectors computations to DWORD/ULONG to prevent potential overflows. Should fix a strange floppy read/write corruption I noticed.

Author: hbelusca
Date: Sat Dec 26 17:08:13 2015
New Revision: 70424

URL: http://svn.reactos.org/svn/reactos?rev=70424&view=rev
Log:
[NTVDM]: Cast all the number-of-sectors computations to DWORD/ULONG to prevent potential
overflows. Should fix a strange floppy read/write corruption I noticed.

Modified:
    trunk/reactos/subsystems/mvdm/ntvdm/bios/bios32/dskbios32.c
    trunk/reactos/subsystems/mvdm/ntvdm/hardware/disk.c

Modified: trunk/reactos/subsystems/mvdm/ntvdm/bios/bios32/dskbios32.c
URL:
http://svn.reactos.org/svn/reactos/trunk/reactos/subsystems/mvdm/ntvdm/bios…
==============================================================================
--- trunk/reactos/subsystems/mvdm/ntvdm/bios/bios32/dskbios32.c	[iso-8859-1] (original)
+++ trunk/reactos/subsystems/mvdm/ntvdm/bios/bios32/dskbios32.c	[iso-8859-1] Sat Dec 26
17:08:13 2015
@@ -608,8 +608,8 @@
                 setAH(0x03);
 
                 /* Number of 512-byte sectors in CX:DX */
-                NumSectors = DiskImage->DiskInfo.Cylinders *
DiskImage->DiskInfo.Heads
-                                                           *
DiskImage->DiskInfo.Sectors;
+                NumSectors = (ULONG)((ULONG)DiskImage->DiskInfo.Cylinders *
DiskImage->DiskInfo.Heads)
+                                                                          *
DiskImage->DiskInfo.Sectors;
                 setCX(HIWORD(NumSectors));
                 setDX(LOWORD(NumSectors));
             }

Modified: trunk/reactos/subsystems/mvdm/ntvdm/hardware/disk.c
URL:
http://svn.reactos.org/svn/reactos/trunk/reactos/subsystems/mvdm/ntvdm/hard…
==============================================================================
--- trunk/reactos/subsystems/mvdm/ntvdm/hardware/disk.c	[iso-8859-1] (original)
+++ trunk/reactos/subsystems/mvdm/ntvdm/hardware/disk.c	[iso-8859-1] Sat Dec 26 17:08:13
2015
@@ -342,7 +342,7 @@
 
     /* Set position */
     // Compute the offset
-    FilePointer = ((Cylinder * DiskImage->DiskInfo.Heads + Head)
+    FilePointer = (DWORD)((DWORD)((DWORD)Cylinder * DiskImage->DiskInfo.Heads + Head)
                     * DiskImage->DiskInfo.Sectors + (Sector - 1))
                     * DiskImage->DiskInfo.SectorSize;
     FilePointer = SetFilePointer(DiskImage->hDisk, FilePointer, NULL, FILE_BEGIN);
@@ -373,7 +373,7 @@
     if (Result != 0x00)
         return Result;
 
-    BytesToRead = NumSectors * DiskImage->DiskInfo.SectorSize;
+    BytesToRead = (DWORD)NumSectors * DiskImage->DiskInfo.SectorSize;
 
     // FIXME: Consider just looping around filling each time the buffer...
 
@@ -434,7 +434,7 @@
     if (Result != 0x00)
         return Result;
 
-    BytesToWrite = NumSectors * DiskImage->DiskInfo.SectorSize;
+    BytesToWrite = (DWORD)NumSectors * DiskImage->DiskInfo.SectorSize;
 
     // FIXME: Consider just looping around filling each time the buffer...