From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752786AbeDSK7i (ORCPT ); Thu, 19 Apr 2018 06:59:38 -0400 Received: from terminus.zytor.com ([198.137.202.136]:36453 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752695AbeDSK7O (ORCPT ); Thu, 19 Apr 2018 06:59:14 -0400 Date: Thu, 19 Apr 2018 03:58:56 -0700 From: tip-bot for Laura Abbott Message-ID: Cc: linux-kernel@vger.kernel.org, hpa@zytor.com, labbott@redhat.com, m@max.pm, tglx@linutronix.de, mingo@kernel.org, john.stultz@linaro.org Reply-To: hpa@zytor.com, linux-kernel@vger.kernel.org, labbott@redhat.com, m@max.pm, tglx@linutronix.de, mingo@kernel.org, john.stultz@linaro.org In-Reply-To: <20180417215742.2521-1-labbott@redhat.com> References: <20180417215742.2521-1-labbott@redhat.com> To: linux-tip-commits@vger.kernel.org Subject: [tip:timers/urgent] posix-cpu-timers: Ensure set_process_cpu_timer is always evaluated Git-Commit-ID: c3bca5d450b620dd3d36e14b5e1f43639fd47d6b 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: c3bca5d450b620dd3d36e14b5e1f43639fd47d6b Gitweb: https://git.kernel.org/tip/c3bca5d450b620dd3d36e14b5e1f43639fd47d6b Author: Laura Abbott AuthorDate: Tue, 17 Apr 2018 14:57:42 -0700 Committer: Thomas Gleixner CommitDate: Thu, 19 Apr 2018 12:54:57 +0200 posix-cpu-timers: Ensure set_process_cpu_timer is always evaluated Commit a9445e47d897 ("posix-cpu-timers: Make set_process_cpu_timer() more robust") moved the check into the 'if' statement. Unfortunately, it did so on the right side of an && which means that it may get short circuited and never evaluated. This is easily reproduced with: $ cat loop.c void main() { struct rlimit res; /* set the CPU time limit */ getrlimit(RLIMIT_CPU,&res); res.rlim_cur = 2; res.rlim_max = 2; setrlimit(RLIMIT_CPU,&res); while (1); } Which will hang forever instead of being killed. Fix this by pulling the evaluation out of the if statement but checking the return value instead. Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1568337 Fixes: a9445e47d897 ("posix-cpu-timers: Make set_process_cpu_timer() more robust") Signed-off-by: Laura Abbott Signed-off-by: Thomas Gleixner Cc: stable@vger.kernel.org Cc: "Max R . P . Grossmann" Cc: John Stultz Link: https://lkml.kernel.org/r/20180417215742.2521-1-labbott@redhat.com --- kernel/time/posix-cpu-timers.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/kernel/time/posix-cpu-timers.c b/kernel/time/posix-cpu-timers.c index 2541bd89f20e..5a6251ac6f7a 100644 --- a/kernel/time/posix-cpu-timers.c +++ b/kernel/time/posix-cpu-timers.c @@ -1205,10 +1205,12 @@ void set_process_cpu_timer(struct task_struct *tsk, unsigned int clock_idx, u64 *newval, u64 *oldval) { u64 now; + int ret; WARN_ON_ONCE(clock_idx == CPUCLOCK_SCHED); + ret = cpu_timer_sample_group(clock_idx, tsk, &now); - if (oldval && cpu_timer_sample_group(clock_idx, tsk, &now) != -EINVAL) { + if (oldval && ret != -EINVAL) { /* * We are setting itimer. The *oldval is absolute and we update * it to be relative, *newval argument is relative and we update