From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752017AbdFTTno (ORCPT ); Tue, 20 Jun 2017 15:43:44 -0400 Received: from terminus.zytor.com ([65.50.211.136]:48159 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751025AbdFTTnm (ORCPT ); Tue, 20 Jun 2017 15:43:42 -0400 Date: Tue, 20 Jun 2017 12:40:02 -0700 From: tip-bot for Thomas Gleixner Message-ID: Cc: john.stultz@linaro.org, peterz@infradead.org, tglx@linutronix.de, hpa@zytor.com, qiuxishi@huawei.com, linux-kernel@vger.kernel.org, mingo@kernel.org Reply-To: tglx@linutronix.de, peterz@infradead.org, hpa@zytor.com, qiuxishi@huawei.com, linux-kernel@vger.kernel.org, mingo@kernel.org, john.stultz@linaro.org In-Reply-To: <20170620154113.588276707@linutronix.de> References: <20170620154113.588276707@linutronix.de> To: linux-tip-commits@vger.kernel.org Subject: [tip:timers/core] posix-cpu-timers: Make timespec to nsec conversion safe Git-Commit-ID: 098b0e01a91c42aaaf0425605cd126b03fcb0bcf X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: 098b0e01a91c42aaaf0425605cd126b03fcb0bcf Gitweb: http://git.kernel.org/tip/098b0e01a91c42aaaf0425605cd126b03fcb0bcf Author: Thomas Gleixner AuthorDate: Tue, 20 Jun 2017 17:37:36 +0200 Committer: Thomas Gleixner CommitDate: Tue, 20 Jun 2017 21:33:56 +0200 posix-cpu-timers: Make timespec to nsec conversion safe The expiry time of a posix cpu timer is supplied through sys_timer_set() via a struct timespec. The timespec is validated for correctness. In the actual set timer implementation the timespec is converted to a scalar nanoseconds value. If the tv_sec part of the time spec is large enough the conversion to nanoseconds (sec * NSEC_PER_SEC) overflows 64bit. Mitigate that by using the timespec_to_ktime() conversion function, which checks the tv_sec part for a potential mult overflow and clamps the result to KTIME_MAX, which is about 292 years. Signed-off-by: Thomas Gleixner Cc: Peter Zijlstra Cc: Xishi Qiu Cc: John Stultz Link: http://lkml.kernel.org/r/20170620154113.588276707@linutronix.de --- kernel/time/posix-cpu-timers.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/kernel/time/posix-cpu-timers.c b/kernel/time/posix-cpu-timers.c index 9df618e..60cb24a 100644 --- a/kernel/time/posix-cpu-timers.c +++ b/kernel/time/posix-cpu-timers.c @@ -580,7 +580,11 @@ static int posix_cpu_timer_set(struct k_itimer *timer, int timer_flags, WARN_ON_ONCE(p == NULL); - new_expires = timespec64_to_ns(&new->it_value); + /* + * Use the to_ktime conversion because that clamps the maximum + * value to KTIME_MAX and avoid multiplication overflows. + */ + new_expires = ktime_to_ns(timespec64_to_ktime(new->it_value)); /* * Protect against sighand release/switch in exit/exec and p->cpu_timers