From owner-freebsd-security  Tue Sep 15 07:40:04 1998
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Date: Tue, 15 Sep 1998 10:40:38 -0400
From: "Jason J. Horton" <jason@intercom.com>
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To: Jay Tribick <netadmin@fastnet.co.uk>
CC: security@FreeBSD.ORG
Subject: Re: grep ohdear /dev/zero in a tight loop freezes FreeBSD && OpenBSD
References: <Pine.BSF.3.96.980915114336.342D-100000@bofh.fast.net.uk>
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Don't allow users on your system.

	-J

Jay Tribick wrote:
> 
> Background
> ----------
> FreeBSD bofh.fast.net.uk 2.2.6-RELEASE FreeBSD 2.2.6-RELEASE #0
> root@bofh.fast.net.uk:/usr/src/sys/compile/GENERIC  i386
> 
> login.conf (ulimit) restrictions:
> 
> lockd:\
>         :priority=20:\
>         :openfiles=32:\
>         :openfiles-cur=32:\
>         :memoryuse-cur=10M:\
>         :maxproc-cur=32:\
>         :cputime=1h:\
>         :stacksize=2M:\
>         :memorylocked=4M:\
>         :memoryuse=10M:\
>         :coredumpsize=0M:\
>         :welcome=/etc/motd.lusers:
> 
> Problem
> -------
> Executing the following shell script effectively freezes a
> BSD box (tested on FreeBSD 2.2.6 & latest OpenBSD) regardless of the above
> process, cpu and memory restrictions within 15-30 seconds:
> 
> #!/bin/bash
> while() do
>         grep ohdear /dev/zero &
> done
> 
> Any ideas on how to fix this or secure against it?
> Regards,
> 
> Jay Tribick <netadmin@fastnet.co.uk>
> --
> [| Network Admin | FastNet International | http://fast.net.uk/ |]
> [| Finger netadmin@fastnet.co.uk for contact info & PGP PubKey |]
> [|   +44 (0)1273 T: 677633 F: 621631 e: netadmin@fast.net.uk   |]
> 
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