From: Michael Brown <mcb30@etherboot.org>
Date: Wed, 27 Aug 2008 19:36:30 +0000 (+0100)
Subject: [util] Fix interpretation of short jumps in Option::ROM
X-Git-Tag: v0.9.4~38
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=bd5189a96d88a27f8c7da29491876ec3790af138;p=thirdparty%2Fipxe.git

[util] Fix interpretation of short jumps in Option::ROM

Option::ROM was assuming that ROM images using a short jump
instruction for the init entry point would have a zero byte at offset
5; this is not necessarily true.
---

diff --git a/src/util/Option/ROM.pm b/src/util/Option/ROM.pm
index 7a1bb8838..a86d32620 100644
--- a/src/util/Option/ROM.pm
+++ b/src/util/Option/ROM.pm
@@ -192,10 +192,12 @@ sub unpack_init {
   my $instr = shift;
 
   # Accept both short and near jumps
-  ( my $jump, my $offset ) = unpack ( "CS", $instr );
+  my $jump = unpack ( "C", $instr );
   if ( $jump == JMP_SHORT ) {
+    my $offset = unpack ( "xC", $instr );
     return ( $offset + 5 );
   } elsif ( $jump == JMP_NEAR ) {
+    my $offset = unpack ( "xS", $instr );
     return ( $offset + 6 );
   } elsif ( $jump == 0 ) {
     return 0;