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-rw-r--r--checkov.pl80
1 files changed, 80 insertions, 0 deletions
diff --git a/checkov.pl b/checkov.pl
new file mode 100644
index 00000000..b9ebf7be
--- /dev/null
+++ b/checkov.pl
@@ -0,0 +1,80 @@
+#!/usr/bin/perl
+#
+# checkov.pl
+#
+# Check NASM map output for overflow
+#
+# This assumes that a section for which start != vstart, both
+# ranges need to be checked for overflow (true for SYSLINUX)
+#
+
+($in, $target) = @ARGV;
+
+sub overlap($$$$) {
+ my($s1,$e1,$s2,$e2) = @_;
+
+ return 1 if ( $s2 < $e1 && $e2 > $s1 );
+ return 1 if ( $s1 < $e2 && $e1 > $s2 );
+
+ return 0;
+}
+
+open(IN, '<', $in) or die "$0: Cannot open input file: $in\n";
+
+$section = undef;
+while ( $line = <IN> ) {
+ if ( $line =~ /^-/ ) {
+ if ( $line =~ /^\-\-\-\- Section (\S+) / ) {
+ $section = $1;
+ } else {
+ $section = undef;
+ }
+ } elsif ( defined($section) ) {
+ if ( $line =~ /^length\:\s*(\S+)/ ) {
+ $length{$section} = hex $1;
+ } elsif ( $line =~ /^start\:\s*(\S+)/ ) {
+ $start{$section} = hex $1;
+ } elsif ( $line =~ /^vstart\:\s*(\S+)/ ) {
+ $vstart{$section} = hex $1;
+ }
+ }
+}
+close(IN);
+
+$err = 0;
+
+foreach $s ( keys(%start) ) {
+ $sstart = $start{$s};
+ $svstart = $vstart{$s};
+ $send = $sstart + $length{$s};
+ $svend = $svstart + $length{$s};
+
+ if ( $send > 0x10000 || $svend > 0x10000 ) {
+ print STDERR "$target: 16-bit overflow on section $s\n";
+ $err++;
+ }
+
+ foreach $o ( keys(%start) ) {
+ next if ( $s ge $o );
+
+ $ostart = $start{$o};
+ $ovstart = $vstart{$o};
+ $oend = $ostart + $length{$o};
+ $ovend = $ovstart + $length{$o};
+
+ if ( overlap($sstart, $send, $ostart, $oend) ||
+ overlap($svstart, $svend, $ostart, $oend) ||
+ overlap($sstart, $send, $ovstart, $ovend) ||
+ overlap($svstart, $svend, $ovstart, $ovend) ) {
+ print STDERR "$target: section $s overlaps section $o\n";
+ $err++;
+ }
+ }
+}
+
+if ( $err ) {
+ unlink($target);
+ exit(1);
+} else {
+ exit(0);
+}