From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755794Ab0J0TVV (ORCPT ); Wed, 27 Oct 2010 15:21:21 -0400 Received: from 74-93-104-97-Washington.hfc.comcastbusiness.net ([74.93.104.97]:42103 "EHLO sunset.davemloft.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752698Ab0J0TVT (ORCPT ); Wed, 27 Oct 2010 15:21:19 -0400 Date: Wed, 27 Oct 2010 12:21:43 -0700 (PDT) Message-Id: <20101027.122143.02260950.davem@davemloft.net> To: nelhage@ksplice.com Cc: robert.olsson@its.uu.se, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, eugene@redhat.com Subject: Re: [PATCH] pktgen: Remove a dangerous debug print. From: David Miller In-Reply-To: <1288206788-21063-1-git-send-email-nelhage@ksplice.com> References: <1288206788-21063-1-git-send-email-nelhage@ksplice.com> X-Mailer: Mew version 6.3 on Emacs 23.1 / Mule 6.0 (HANACHIRUSATO) Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Nelson Elhage Date: Wed, 27 Oct 2010 15:13:08 -0400 > We were allocating an arbitrarily-large buffer on the stack, which would allow a > buggy or malicious userspace program to overflow the kernel stack. > > Since the debug printk() was just printing exactly the text passed from > userspace, it's probably just as easy for anyone who might use it to augment (or > just strace(1)) the program writing to the pktgen file, so let's just not bother > trying to print the whole buffer. > > Signed-off-by: Nelson Elhage Only root can write to the pktgen control file. Also, the debug feature really is used by people's pktgen scripts, you can't just turn it off.