From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S935682Ab3BOKIU (ORCPT ); Fri, 15 Feb 2013 05:08:20 -0500 Received: from mx1.redhat.com ([209.132.183.28]:10832 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754911Ab3BOKIR (ORCPT ); Fri, 15 Feb 2013 05:08:17 -0500 Date: Fri, 15 Feb 2013 11:08:11 +0100 From: Stanislaw Gruszka To: Oleg Nesterov , Thomas Gleixner Cc: LKML , Dave Jones , John Stultz , Tommi Rantala , Andrew Morton Subject: [PATCH v2 repost] posix-cpu-timers: fix nanosleep task_struct leak Message-ID: <20130215100810.GF4392@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org In do_cpu_nanosleep() we do posic_cpu_timer_create(), but forgot corresponding posix_cpu_timer_del() what lead to task_struct leak. Reported-and-tested-by: Tommi Rantala Signed-off-by: Stanislaw Gruszka Cc: stable@vger.kernel.org --- v1 -> v2: add comments This looks like DoS problem fix, since it's possible to eat kernel memory (very slowly though) by normal user, hence Cc stable. kernel/posix-cpu-timers.c | 23 +++++++++++++++++++++-- 1 file changed, 21 insertions(+), 2 deletions(-) diff --git a/kernel/posix-cpu-timers.c b/kernel/posix-cpu-timers.c index a278cad..942ca27 100644 --- a/kernel/posix-cpu-timers.c +++ b/kernel/posix-cpu-timers.c @@ -1401,8 +1401,10 @@ static int do_cpu_nanosleep(const clockid_t which_clock, int flags, while (!signal_pending(current)) { if (timer.it.cpu.expires.sched == 0) { /* - * Our timer fired and was reset. + * Our timer fired and was reset, below + * deletion can not fail. */ + posix_cpu_timer_del(&timer); spin_unlock_irq(&timer.it_lock); return 0; } @@ -1420,9 +1422,26 @@ static int do_cpu_nanosleep(const clockid_t which_clock, int flags, * We were interrupted by a signal. */ sample_to_timespec(which_clock, timer.it.cpu.expires, rqtp); - posix_cpu_timer_set(&timer, 0, &zero_it, it); + error = posix_cpu_timer_set(&timer, 0, &zero_it, it); + if (!error) { + /* + * Timer is now unarmed, deletion can not fail. + */ + posix_cpu_timer_del(&timer); + } spin_unlock_irq(&timer.it_lock); + while (error == TIMER_RETRY) { + /* + * We need to handle case when timer was or is in the + * middle of firing. In other cases we already freed + * resources. + */ + spin_lock_irq(&timer.it_lock); + error = posix_cpu_timer_del(&timer); + spin_unlock_irq(&timer.it_lock); + } + if ((it->it_value.tv_sec | it->it_value.tv_nsec) == 0) { /* * It actually did fire already. -- 1.7.11.7