From: H. Peter Anvin <hpa@zytor.com>
Date: Fri, 21 Sep 2007 23:22:58 +0000 (-0700)
Subject: comboot: fix memory overwrite bug
X-Git-Tag: syslinux-3.52-pre9~2
X-Git-Url: http://git.kernel.org/?p=boot%2Fsyslinux%2Fsyslinux.git;a=commitdiff_plain;h=426d986dbc77abf2247b08c44c18bf9a478c2e8e

comboot: fix memory overwrite bug

Fix memory overwrite bug, specifically, the use of BP after it might
have gotten clobbered.  Since at the point of use, BP is supposed to
be == SP, we can just add "mov bp,sp".
---

diff --git a/comboot.inc b/comboot.inc
index 3c9df5f..ffc9425 100644
--- a/comboot.inc
+++ b/comboot.inc
@@ -187,6 +187,7 @@ comboot_int21:	cli
 		clc
 		call ax			; Call the invoked function
 comboot_resume:
+		mov bp,sp		; In case the function clobbers BP
 		setc P_FLAGSL		; Propagate CF->error
 		popad
 		pop gs