#!/usr/bin/perl -wl
use strict;

my $hashref = { foo => { bar => 'xyzzy' } };

sub name_me {
    # Note: there is no $hashref->{foo}{foo}
    return \ $hashref->{foo}{foo};
}

print ${ name_me() };

# Note: I narrowed it down to this code. The original code
# was about 50 lines. Because this is just a fragment, I couldn't
# think of a proper name for the sub. Sorry :)

##</code><code>##

2;0 juerd@ouranos:~$ perl -e'undef christmas'
Segmentation fault
2;139 juerd@ouranos:~$