Subject: Re: Boot netbsd on playstation2 with modchip
To: None <>
From: der Mouse <mouse@Rodents.Montreal.QC.CA>
List: port-playstation2
Date: 12/17/2006 22:23:41
>> I'd certainly appreciate any work done on lifting [the dependence on
>> the Sony Linux kit].  I'd be very interested in booting NetBSD on
>> mine via some variant of the Independence Day exploit [...]
> How does the ID exploit work?

Note that the following is second-hand knowledge, except where I
specifically mention my own case.  While my machine behaves more or
less as though it were accurate, I have not dug deep enough to verify
the details myself.

It's a classic smash-the-stack buffer overflow.  When booting a PS1
game, it takes the game's ID (eg, SCUS 63524 - an invented but
plausible-looking example - these are usually present on the game's
jewel case packaging) and looks on any PS2 memory cards in place,
looking for a file with a fixed name I forget.  If it find the file, it
reads thorugh it, looking for a line giving the game's ID.  If found,
the rest of the line is treated as various options - this is presumably
intended to allow specifying quirks for cases where the default PS1
emulation is not quite good enough for the game, though I don't know of
any examples.

But the line, if found, is copied into a fixed-size buffer on the
stack, which turns out to always be at the same address.  Trivial to
exploit.  The only hard part is getting a suitable file onto your
memory card in the first place.  Someone who already has it installed
can write it for you (that's how I got started); there's a commercial
product called HDloader which also suffices, if you have Linux on your
house LAN and a disk (not necessarily the Sony one) in your PS2 - the
disk might not actually be necessary.  I conjecture the Linux kit also
works; I would expect a PS2 dev station to work as well, but I
understand Sony is downright paranoid about their getting into
unconsecrated hands.

> Of course, the one nice thing you do get with the Linux kit is the
> VGA adapter.. although I suppose this isn't as big of a deal these
> days with HDTVs becoming cheaper and cheaper.

I don't expect to buy an HDTV because (almost?) all of them here would
come from the States and thus contain DRM crippling.  But a friend of
mine (the one who first got me into console gaming, by giving me a
PSone) gave me a scan doubler which turns a TV signal into something a
typical VGA monitor can handle.

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