From owner-freebsd-security Tue Jul 10 21: 3:44 2001 Delivered-To: freebsd-security@freebsd.org Received: from sneakerz.org (sneakerz.org [216.33.66.254]) by hub.freebsd.org (Postfix) with ESMTP id 04F5437B401 for ; Tue, 10 Jul 2001 21:03:41 -0700 (PDT) (envelope-from bright@sneakerz.org) Received: by sneakerz.org (Postfix, from userid 1092) id D43585D01F; Tue, 10 Jul 2001 23:03:29 -0500 (CDT) Date: Tue, 10 Jul 2001 23:03:29 -0500 From: Alfred Perlstein To: "Robert E. Lee" Cc: Dag-Erling Smorgrav , Ted Mittelstaedt , js43064n@pace.edu, freebsd-security@FreeBSD.ORG Subject: Re: Kernel Panic Message-ID: <20010710230329.A1894@sneakerz.org> References: Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.2i In-Reply-To: ; from rel@gulbransen.com on Tue, Jul 10, 2001 at 08:54:19PM -0700 Sender: owner-freebsd-security@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.org * Robert E. Lee [010710 22:54] wrote: > On 24 Jun 2001, Dag-Erling Smorgrav wrote: > > "Ted Mittelstaedt" writes: > > A disk error would not crash the system. Please stop spouting > > unfounded (though highly imaginative) bullshit. > > Not to get into a pissing contest, but I have had disk errors in the past > that made my system crash. > > On the original thread, when you have a local account on a box, you can > usually use this script as an effective DoS: > > $ more foo.sh > #!/bin/sh > > while [ 1 -eq 1 ]; do > find / -name foo & > done > > The default settings for most Unix OS's allow that type of script to > consume enough resources to make the system unusable. It'd be almost trivial to limit the amount of outstanding IO on a per uid basis. Have time for a patch? :) Hint: store the amount of IO in the uidinfo struct, if you go out of bounds, sleep on the outstanding buf counter address for a short time (*), if the user completes IO, then issue a wakeup. (*) the reason you can not sleep inifinitely is because you may cause a deadlock situation against yourself when writing out dirty buffers, or maybe not.. ? Anyhow, that should allow for throttling. -- -Alfred Perlstein [alfred@freebsd.org] Ok, who wrote this damn function called '??'? And why do my programs keep crashing in it? To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-security" in the body of the message