From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Wed, 3 Jan 2001 20:52:41 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Wed, 3 Jan 2001 20:52:32 -0500 Received: from Cantor.suse.de ([194.112.123.193]:63236 "HELO Cantor.suse.de") by vger.kernel.org with SMTP id ; Wed, 3 Jan 2001 20:52:22 -0500 Date: Thu, 4 Jan 2001 02:51:53 +0100 From: Andi Kleen To: Alexander Viro Cc: Dan Aloni , linux-kernel , mark@itsolve.co.uk Subject: Re: [RFC] prevention of syscalls from writable segments, breaking bug exploits Message-ID: <20010104025153.A15359@gruyere.muc.suse.de> In-Reply-To: Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.2.5i In-Reply-To: ; from viro@math.psu.edu on Wed, Jan 03, 2001 at 04:54:38PM -0500 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jan 03, 2001 at 04:54:38PM -0500, Alexander Viro wrote: > > Win: 0 > Loss: cost of find_vma() (and down(&mm->mmap_sem), BTW) on every system It could actually be optimized a lot, e.g. by just read/writing to a byte in the caller's current code page and handling the exception. But I agree with you that it's rather useless. It'll break some existing exploits, but it's so easy to workaround that exploit writers would quickly adapt and then you have a ugly check with no purpose after a few weeks. -Andi - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org Please read the FAQ at http://www.tux.org/lkml/