Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S937836AbXHLTGc (ORCPT ); Sun, 12 Aug 2007 15:06:32 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S937494AbXHLTF6 (ORCPT ); Sun, 12 Aug 2007 15:05:58 -0400 Received: from www.osadl.org ([213.239.205.134]:33511 "EHLO mail.tglx.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S937371AbXHLTF5 (ORCPT ); Sun, 12 Aug 2007 15:05:57 -0400 Subject: Re: [PATCH 2/4] posix-timers: fix creation race From: Thomas Gleixner To: Oleg Nesterov Cc: Andrew Morton , Ingo Molnar , linux-kernel@vger.kernel.org, stable@kernel.org In-Reply-To: <20070812170522.GA4299@tv-sign.ru> References: <20070812170522.GA4299@tv-sign.ru> Content-Type: text/plain Date: Sun, 12 Aug 2007 21:05:55 +0200 Message-Id: <1186945555.12828.89.camel@chaos> Mime-Version: 1.0 X-Mailer: Evolution 2.10.1 (2.10.1-4.fc7) Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1641 Lines: 40 On Sun, 2007-08-12 at 21:05 +0400, Oleg Nesterov wrote: > sys_timer_create() sets ->it_process and unlocks ->siglock, then checks > tmr->it_sigev_notify to define if get_task_struct() is needed. > > We already passed ->it_id to the caller, another thread can delete this > timer and free its memory in between. > > As a minimal fix, move this code under ->siglock, sys_timer_delete() takes > it too before calling release_posix_timer(). A proper serialization would > be to take ->it_lock, we add a partly initialized timer on posix_timers_id, > not good. > > Signed-off-by: Oleg Nesterov Acked-by: Thomas Gleixner > --- t/kernel/posix-timers.c~2_CREATE 2007-08-12 17:59:17.000000000 +0400 > +++ t/kernel/posix-timers.c 2007-08-12 18:11:33.000000000 +0400 > @@ -547,13 +547,12 @@ sys_timer_create(const clockid_t which_c > new_timer->it_process = process; > list_add(&new_timer->list, > &process->signal->posix_timers); > - spin_unlock_irqrestore(&process->sighand->siglock, flags); > if (new_timer->it_sigev_notify == (SIGEV_SIGNAL|SIGEV_THREAD_ID)) > get_task_struct(process); > } else { > - spin_unlock_irqrestore(&process->sighand->siglock, flags); > process = NULL; > } > + spin_unlock_irqrestore(&process->sighand->siglock, flags); > } > read_unlock(&tasklist_lock); > if (!process) { > - 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/