From owner-freebsd-security@FreeBSD.ORG Fri Sep 18 22:15:14 2009 Return-Path: Delivered-To: freebsd-security@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id C0370106566B for ; Fri, 18 Sep 2009 22:15:14 +0000 (UTC) (envelope-from drosih@rpi.edu) Received: from smtp5.server.rpi.edu (smtp5.server.rpi.edu [128.113.2.225]) by mx1.freebsd.org (Postfix) with ESMTP id 0C7DF8FC0C for ; Fri, 18 Sep 2009 22:15:13 +0000 (UTC) Received: from [128.113.24.47] (gilead.netel.rpi.edu [128.113.24.47]) by smtp5.server.rpi.edu (8.13.1/8.13.1) with ESMTP id n8IL0Ngu020233; Fri, 18 Sep 2009 17:00:25 -0400 Mime-Version: 1.0 Message-Id: In-Reply-To: <20090919.001313.110616099.hdk_2@yahoo.co.jp> References: <4AAF4A64.3080906@thedarkside.nl> <20090919.001313.110616099.hdk_2@yahoo.co.jp> Date: Fri, 18 Sep 2009 17:00:22 -0400 To: Hideki EIRAKU , pieter@thedarkside.nl From: Garance A Drosihn Content-Type: text/plain; charset="us-ascii" ; format="flowed" X-Bayes-Prob: 0.0001 (Score 0) X-RPI-SA-Score: 0.00 () [Hold at 20.00] 22490(-25) X-CanItPRO-Stream: outgoing X-Canit-Stats-ID: Bayes signature not available X-Scanned-By: CanIt (www . roaringpenguin . com) on 128.113.2.225 Cc: freebsd-security@freebsd.org Subject: Re: Protecting against kernel NULL-pointer derefs X-BeenThere: freebsd-security@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: "Security issues \[members-only posting\]" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 18 Sep 2009 22:15:14 -0000 At 12:13 AM +0900 9/19/09, Hideki EIRAKU wrote: >From: Pieter de Boer >Subject: Protecting against kernel NULL-pointer derefs >Date: Tue, 15 Sep 2009 10:03:48 +0200 > >> - Are there unwanted side-effects of raising VM_MIN_ADDRESS? > >Mapping at address 0x0 is needed by some softwares using vm86 mode. >For example, emulators/doscmd uses vm86 mode to emulate an old DOS >environment. In this case, the address 0x0 - 0x3ff is used for an >interrupt vector of emulated DOS world. If VM_MIN_ADDRESS is not >zero, doscmd doesn't work. vm86 mode is in 32bit i386 architecture >only, not in amd64 or other architectures. Could we: a) alter those programs so they didn't need that vector in page 0? or b) provide some system call or other facility which would allow *that* process to use page 0? -- Garance Alistair Drosehn = gad@gilead.netel.rpi.edu Senior Systems Programmer or gad@freebsd.org Rensselaer Polytechnic Institute or drosih@rpi.edu