Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751201AbXAZKkK (ORCPT ); Fri, 26 Jan 2007 05:40:10 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932566AbXAZKkK (ORCPT ); Fri, 26 Jan 2007 05:40:10 -0500 Received: from ecfrec.frec.bull.fr ([129.183.4.8]:45990 "EHLO ecfrec.frec.bull.fr" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751201AbXAZKkI convert rfc822-to-8bit (ORCPT ); Fri, 26 Jan 2007 05:40:08 -0500 Date: Fri, 26 Jan 2007 11:39:06 +0100 From: =?ISO-8859-1?Q?S=E9bastien_Dugu=E9?= To: Oleg Nesterov Cc: Zach Brown , Suparna Bhattacharya , Benjamin LaHaise , Ulrich Drepper , Ingo Molnar , Thomas Gleixner , Andrew Morton , linux-kernel@vger.kernel.org Subject: Re: + make-good_sigevent-non-static.patch added to -mm tree Message-ID: <20070126113906.0505a734@frecb000686> In-Reply-To: <20070126100801.GA94@tv-sign.ru> References: <20070125154324.GA183@tv-sign.ru> <20070126103208.78c4937f@frecb000686> <20070126100801.GA94@tv-sign.ru> X-Mailer: Sylpheed-Claws 2.6.0 (GTK+ 2.8.20; i486-pc-linux-gnu) Mime-Version: 1.0 X-MIMETrack: Itemize by SMTP Server on ECN002/FR/BULL(Release 5.0.12 |February 13, 2003) at 26/01/2007 11:40:58, Serialize by Router on ECN002/FR/BULL(Release 5.0.12 |February 13, 2003) at 26/01/2007 11:40:58, Serialize complete at 26/01/2007 11:40:58 Content-Transfer-Encoding: 8BIT Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1872 Lines: 60 On Fri, 26 Jan 2007 13:08:01 +0300 Oleg Nesterov wrote: > On 01/26, S?bastien Dugu? wrote: > > > > On Thu, 25 Jan 2007 18:43:24 +0300 Oleg Nesterov wrote: > > > > > SИbastien DuguИ wrote: > > > > > > > > +struct task_struct *good_sigevent(sigevent_t *event) > > > > +{ > > > > + struct task_struct *task = current->group_leader; > > > > + > > > > + if ((event->sigev_notify & SIGEV_THREAD_ID) == SIGEV_THREAD_ID) { > > > > + task = find_task_by_pid(event->sigev_notify_thread_id); > > > > + > > > > + if (!task || task->tgid != current->tgid) > > > > + return NULL; > > > > + } else if (event->sigev_notify == SIGEV_SIGNAL) { > > > > > > No, no, we can't use "else" here, > > > > > > > + if (event->sigev_signo <= 0 || event->sigev_signo > SIGRTMAX) > > > > > > because we skip the check above in SIGEV_THREAD_ID case. > > > > Right, will fix this. > > > > > > > > This way any user can crash the kernel with a minimal effort. > > > > Well I tried, no crash, just the signal failing to be delivered. > > sigaddset: > > set->sig[sig / _NSIG_BPW] |= 1UL << (sig % _NSIG_BPW); > > This writes to ->sig[event->sigev_signo / _NSIG_BPW] location, so we can > corrupt the memory if ->sigev_signo > _NSIG. Gawd, right. > > Btw, since you are exporting this function, may I suggest to rename it? > No, I can't suggest a better name :) But "good_sigevent" is a bit confusing > imho. I agree, there was a discussion concerning this a while back but nothing came out of it and I left it as is. I will try to find something more suggestive. Thanks, Sébastien. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/