Re: Why wrapping PIDs is evil [was 32bit]

From: Pavel Machek (pavel@suse.cz)
Date: Sun Jan 16 2000 - 15:32:05 EST


Hi!

> > Sorry, alan. No. Unix is broken with this part.
>
> When you run as root, you run risks and have to be careful.

No. You can't be carefull. Users have full chance to get you in this case.

> thing about Unix is that it wraps pids and does _not_ pick random pids. You shouldn't
> get around to the same pid for at least a reasonable amount of time, unless someone
> is spawning processes _very_ fast.

But someone probably _is_ spawning processes very fast if they want to
screw you.

> > But that's wrong. Pavel may have seen you are going to kill his emacs
> > and may have wrapped pids, killed his emacs himself, and you are now
> > killing _your_ netscape you've just ran.
>
> Erm, too bad that's exactly what _doesn't_ happen under Unix. Your netscape
> you just started will get a new pid, after the latest one taken. No matter if that
> process died or not.

I forgot to mention: of course _pavel_ is evil and created/killed just
enough processes for PIDs to wrap in bad way.

                                                                Pavel

-- 
I'm pavel@ucw.cz. "In my country we have almost anarchy and I don't care."
Panos Katsaloulis describing me w.r.t. patents me at discuss@linmodems.org

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