From: Michael Brown <mcb30@etherboot.org>
Date: Thu, 31 Aug 2006 13:25:45 +0000 (+0000)
Subject: Check to see if we've reached the end of the map before attempting to
X-Git-Tag: v0.9.3~1060
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=78dd963c1fc423673a890c8b761e40906252bfef;p=thirdparty%2Fipxe.git

Check to see if we've reached the end of the map before attempting to
skip past an empty region, otherwise we end up generating an infinitely
long e820 map.  (Yes, there *are* real systems that provide e820 maps
with a zero-length region at the end...)
---

diff --git a/src/arch/i386/firmware/pcbios/e820mangler.S b/src/arch/i386/firmware/pcbios/e820mangler.S
index 89030a49e..21d1bb9a5 100644
--- a/src/arch/i386/firmware/pcbios/e820mangler.S
+++ b/src/arch/i386/firmware/pcbios/e820mangler.S
@@ -361,7 +361,12 @@ int15_e820:
 	pushl	%edx	
 	call	split_e820
 	pushfw
+	/* Skip empty region checking if we've reached the end of the
+	 * map or hit an error, to avoid a potential endless loop.
+	 */
 	jc	1f
+	testl	%ebx, %ebx
+	jz	1f
 	/* Check for an empty region */
 	pushl	%eax
 	movl	%es:8(%di), %eax