From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1161044AbWBYSZs (ORCPT ); Sat, 25 Feb 2006 13:25:48 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1161045AbWBYSZs (ORCPT ); Sat, 25 Feb 2006 13:25:48 -0500 Received: from smtpout.mac.com ([17.250.248.86]:17612 "EHLO smtpout.mac.com") by vger.kernel.org with ESMTP id S1161044AbWBYSZs (ORCPT ); Sat, 25 Feb 2006 13:25:48 -0500 In-Reply-To: <200602241237.21628.mbuesch@freenet.de> References: <200602241237.21628.mbuesch@freenet.de> Mime-Version: 1.0 (Apple Message framework v746.2) Content-Type: text/plain; charset=US-ASCII; delsp=yes; format=flowed Message-Id: Cc: Jan Engelhardt , Linux Kernel Mailing List Content-Transfer-Encoding: 7bit From: Kyle Moffett Subject: Re: Mapping to 0x0 Date: Sat, 25 Feb 2006 13:25:33 -0500 To: Michael Buesch X-Mailer: Apple Mail (2.746.2) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Feb 24, 2006, at 06:37:21, Michael Buesch wrote: > I am playing around with it. I did the attached code. It is a > usermode program, which tries to map NULL, and a kernel module, > which calls a NULL pointer. The file badcode.bin contains an i386 > ud2 instruction. When loading the kernel module, while the usermode > program is executing, I get the usual NULL pointer dereference oops: You need to trigger the null pointer dereference from within the userspace program that maps NULL. The reason your test doesn't do anything is that it is the insmod tool whose address space gets used, as opposed to your nulltest program. Cheers, Kyle Moffett