From owner-freebsd-stable@FreeBSD.ORG Mon Jun 11 20:54:29 2007 Return-Path: X-Original-To: freebsd-stable@freebsd.org Delivered-To: freebsd-stable@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [69.147.83.52]) by hub.freebsd.org (Postfix) with ESMTP id C2CFF16A469 for ; Mon, 11 Jun 2007 20:54:29 +0000 (UTC) (envelope-from cswiger@mac.com) Received: from mail-out4.apple.com (mail-out4.apple.com [17.254.13.23]) by mx1.freebsd.org (Postfix) with ESMTP id AB35413C4CB for ; Mon, 11 Jun 2007 20:54:29 +0000 (UTC) (envelope-from cswiger@mac.com) Received: from relay5.apple.com (relay5.apple.com [17.128.113.35]) by mail-out4.apple.com (Postfix) with ESMTP id A10EE8B77F3; Mon, 11 Jun 2007 13:54:29 -0700 (PDT) Received: from relay5.apple.com (unknown [127.0.0.1]) by relay5.apple.com (Symantec Mail Security) with ESMTP id 8E48529C003; Mon, 11 Jun 2007 13:54:29 -0700 (PDT) X-AuditID: 11807123-9e01ebb000000a23-82-466db685e7b8 Received: from [17.214.13.96] (cswiger1.apple.com [17.214.13.96]) (using TLSv1 with cipher AES128-SHA (128/128 bits)) (No client certificate requested) by relay5.apple.com (Apple SCV relay) with ESMTP id 7CDBE30400E; Mon, 11 Jun 2007 13:54:29 -0700 (PDT) In-Reply-To: <002b01c7ac50$6cd44400$467ccc00$@ca> References: <468d29450706110830k5faf022n9a417157bcf3f544@mail.gmail.com> <002b01c7ac50$6cd44400$467ccc00$@ca> Mime-Version: 1.0 (Apple Message framework v752.2) Content-Type: text/plain; charset=US-ASCII; delsp=yes; format=flowed Message-Id: <7F6FEDFB-EB48-4882-B033-5026EB037641@mac.com> Content-Transfer-Encoding: 7bit From: Chuck Swiger Date: Mon, 11 Jun 2007 13:54:28 -0700 To: Kevin K. X-Mailer: Apple Mail (2.752.2) X-Brightmail-Tracker: AAAAAA== Cc: freebsd-stable@freebsd.org Subject: Re: DDoS in FreeBSD 6.2-STABLE And Problen With The Clock X-BeenThere: freebsd-stable@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Production branch of FreeBSD source code List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 11 Jun 2007 20:54:29 -0000 On Jun 11, 2007, at 10:46 AM, Kevin K. wrote: >> There are some problems, first DDoS (hardware DDoS) in the system. > > I'd like to know what you mean by "hardware DDoS" I'm not sure what the OP meant, but I can provide examples of a hardware DDoS. Way back when, certain machines were equipped with a Motorola/TI 56001 DSP, which had three separate, parallel execution units, and was an early example of SIMD/VLIW design. It turns out that if you issued an instruction to all three pipelines [1] which loaded or saved to the same memory address, you would fry the DSP chip. The compiler used to generate the code for the 56K DSP chip would prevent this unfortunate event by reordering instructions if needed, but if you wrote your own assembly, you could in fact do a hardware DDoS if you weren't careful. :-) -- -Chuck [1] IIRC, it could deal with two pipelines hitting the same address, but not all three.