From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S267175AbUBSKiS (ORCPT ); Thu, 19 Feb 2004 05:38:18 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S267177AbUBSKiS (ORCPT ); Thu, 19 Feb 2004 05:38:18 -0500 Received: from fw.osdl.org ([65.172.181.6]:40326 "EHLO mail.osdl.org") by vger.kernel.org with ESMTP id S267175AbUBSKiN (ORCPT ); Thu, 19 Feb 2004 05:38:13 -0500 Date: Thu, 19 Feb 2004 02:38:13 -0800 From: Andrew Morton To: Nikita Danilov Cc: linux-kernel@vger.kernel.org, ltp-list@lists.sourceforge.net, error27@email.com Subject: Re: [Announce] Strace Test Message-Id: <20040219023813.2d4b0ced.akpm@osdl.org> In-Reply-To: <16436.35563.593635.277584@laputa.namesys.com> References: <20040216052257.A2C971D7214@ws3-3.us4.outblaze.com> <16436.35563.593635.277584@laputa.namesys.com> X-Mailer: Sylpheed version 0.9.4 (GTK+ 1.2.10; i686-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Nikita Danilov wrote: > > > Strace Test uses a modified version of strace 4.5.1. > > Instead of printing out information about system calls, > > the modified version calls the syscalls with improper > > values. > > It immediately DoSes kernel by calling sys_sysctl() with huge nlen: > printk() consumes all CPU. Something like this? --- 25/kernel/sysctl.c~sysctl-nlen-check 2004-02-19 02:36:20.000000000 -0800 +++ 25-akpm/kernel/sysctl.c 2004-02-19 02:37:40.000000000 -0800 @@ -913,6 +913,9 @@ asmlinkage long sys_sysctl(struct __sysc if (copy_from_user(&tmp, args, sizeof(tmp))) return -EFAULT; + + if (tmp.nlen < 0 || tmp.nlen > CTL_MAXNAME) + return -EINVAL; if (tmp.nlen != 2 || copy_from_user(name, tmp.name, sizeof(name)) || name[0] != CTL_KERN || name[1] != KERN_VERSION) { _