core: When checking for DS:SI validity, we're using paragraph units

We are comparing DS:SI for a sane range, but we're operating in paragraph units, so the comparison needs to be done that way, too. Reported-by: Keshav P.R. <skodabenz@gmail.com> Debugged-by: Michal Soltys <soltys@ziu.info> Signed-off-by: H. Peter Anvin <hpa@zytor.com>
mcb30 · Feb 21, 2011 · 102b58a · 102b58a
1 parent 5c93089
commit 102b58a
Showing 1 changed file with 2 additions and 2 deletions.
diff --git a/core/diskboot.inc b/core/diskboot.inc
@@ -1,7 +1,7 @@
 ; -----------------------------------------------------------------------
 ;
 ;   Copyright 1994-2009 H. Peter Anvin - All Rights Reserved
-;   Copyright 2009-2010 Intel Corporation; author: H. Peter Anvin
+;   Copyright 2009-2011 Intel Corporation; author: H. Peter Anvin
 ;
 ;   This program is free software; you can redistribute it and/or modify
 ;   it under the terms of the GNU General Public License as published by
@@ -185,7 +185,7 @@ harddisk:
 		shr si,4
 		jz .no_partition	; SI == 0 -> assume no partition
 		add dx,si
-		cmp dx,1024		; DS:SI < 1K (inside the IVT)?
+		cmp dx,1024 >> 4	; DS:SI < 1K (inside the IVT)?
 		jb .no_partition
 		cmp dx,PartInfo >> 4	; DS:SI in overwritten memory?
 		jae .no_partition