From: John Stultz <john.stultz@linaro.org>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: Kees Cook <keescook@chromium.org>, Xing Gao <xgao01@email.wm.edu>,
Jessica Frazelle <me@jessfraz.com>,
"Eric W. Biederman" <ebiederm@xmission.com>,
Jonathan Corbet <corbet@lwn.net>, Tejun Heo <tj@kernel.org>,
Lai Jiangshan <jiangshanlai@gmail.com>,
Petr Mladek <pmladek@suse.com>,
Andrew Morton <akpm@linux-foundation.org>,
Oleg Nesterov <oleg@redhat.com>,
Nicolas Iooss <nicolas.iooss_linux@m4x.org>,
Nicolas Pitre <nicolas.pitre@linaro.org>,
Richard Cochran <richardcochran@gmail.com>,
"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
Michal Marek <mmarek@suse.com>,
Josh Poimboeuf <jpoimboe@redhat.com>,
Dmitry Vyukov <dvyukov@google.com>,
Olof Johansson <olof@lixom.net>, Shuah Khan <shuah@kernel.org>,
linux-doc@vger.kernel.org, lkml <linux-kernel@vger.kernel.org>,
kernel-hardening@lists.openwall.com
Subject: Re: [PATCH] time: Remove CONFIG_TIMER_STATS
Date: Wed, 8 Feb 2017 10:09:39 -0800 [thread overview]
Message-ID: <CALAqxLU2OTBk1gmiZgoQ2ZzF6eOuOyCGEUNqXXuq+koZ1mYceA@mail.gmail.com> (raw)
In-Reply-To: <alpine.DEB.2.20.1702081122190.3536@nanos>
On Wed, Feb 8, 2017 at 2:24 AM, Thomas Gleixner <tglx@linutronix.de> wrote:
> On Tue, 7 Feb 2017, John Stultz wrote:
>> On Tue, Feb 7, 2017 at 3:40 PM, Kees Cook <keescook@chromium.org> wrote:
>> > Currently CONFIG_TIMER_STATS exposes process information across namespaces:
>> >
>> > kernel/time/timer_list.c print_timer():
>> >
>> > SEQ_printf(m, ", %s/%d", tmp, timer->start_pid);
>> >
>> > /proc/timer_list:
>> >
>> > #11: <0000000000000000>, hrtimer_wakeup, S:01, do_nanosleep, cron/2570
>> >
>> > Given that the tracer can give the same information, this patch entirely
>> > removes CONFIG_TIMER_STATS.
>> >
>> > Suggested-by: Thomas Gleixner <tglx@linutronix.de>
>> > Signed-off-by: Kees Cook <keescook@chromium.org>
>>
>> I don't have an issue with this, but I worry this would break some
>> tooling out there. Should it be marked as deprecated first?
>>
>> Or maybe just pulling the band-aid off is the best way?
>
> I think we should just kill it.
>
> No tools can really rely on the behaviour of that file because it depends
> on CONFIG_TIMER_STATS and the information available there is just a random
> snapshot of queued timers at a given point of time, which is in no way
> usefull.
Fair enough.
Acked-by: John Stultz <john.stultz@linaro.org>
WARNING: multiple messages have this Message-ID (diff)
From: John Stultz <john.stultz@linaro.org>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: Kees Cook <keescook@chromium.org>, Xing Gao <xgao01@email.wm.edu>,
Jessica Frazelle <me@jessfraz.com>,
"Eric W. Biederman" <ebiederm@xmission.com>,
Jonathan Corbet <corbet@lwn.net>, Tejun Heo <tj@kernel.org>,
Lai Jiangshan <jiangshanlai@gmail.com>,
Petr Mladek <pmladek@suse.com>,
Andrew Morton <akpm@linux-foundation.org>,
Oleg Nesterov <oleg@redhat.com>,
Nicolas Iooss <nicolas.iooss_linux@m4x.org>,
Nicolas Pitre <nicolas.pitre@linaro.org>,
Richard Cochran <richardcochran@gmail.com>,
"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
Michal Marek <mmarek@suse.com>,
Josh Poimboeuf <jpoimboe@redhat.com>,
Dmitry Vyukov <dvyukov@google.com>,
Olof Johansson <olof@lixom.net>, Shuah Khan <shuah@kernel.org>,
linux-doc@vger.kernel.org, lkml <linux-kernel@vger.kernel.org>,
kernel-hardening@lists.openwall.com
Subject: [kernel-hardening] Re: [PATCH] time: Remove CONFIG_TIMER_STATS
Date: Wed, 8 Feb 2017 10:09:39 -0800 [thread overview]
Message-ID: <CALAqxLU2OTBk1gmiZgoQ2ZzF6eOuOyCGEUNqXXuq+koZ1mYceA@mail.gmail.com> (raw)
In-Reply-To: <alpine.DEB.2.20.1702081122190.3536@nanos>
On Wed, Feb 8, 2017 at 2:24 AM, Thomas Gleixner <tglx@linutronix.de> wrote:
> On Tue, 7 Feb 2017, John Stultz wrote:
>> On Tue, Feb 7, 2017 at 3:40 PM, Kees Cook <keescook@chromium.org> wrote:
>> > Currently CONFIG_TIMER_STATS exposes process information across namespaces:
>> >
>> > kernel/time/timer_list.c print_timer():
>> >
>> > SEQ_printf(m, ", %s/%d", tmp, timer->start_pid);
>> >
>> > /proc/timer_list:
>> >
>> > #11: <0000000000000000>, hrtimer_wakeup, S:01, do_nanosleep, cron/2570
>> >
>> > Given that the tracer can give the same information, this patch entirely
>> > removes CONFIG_TIMER_STATS.
>> >
>> > Suggested-by: Thomas Gleixner <tglx@linutronix.de>
>> > Signed-off-by: Kees Cook <keescook@chromium.org>
>>
>> I don't have an issue with this, but I worry this would break some
>> tooling out there. Should it be marked as deprecated first?
>>
>> Or maybe just pulling the band-aid off is the best way?
>
> I think we should just kill it.
>
> No tools can really rely on the behaviour of that file because it depends
> on CONFIG_TIMER_STATS and the information available there is just a random
> snapshot of queued timers at a given point of time, which is in no way
> usefull.
Fair enough.
Acked-by: John Stultz <john.stultz@linaro.org>
next prev parent reply other threads:[~2017-02-08 18:09 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-02-07 23:40 [PATCH] time: Remove CONFIG_TIMER_STATS Kees Cook
2017-02-07 23:40 ` [kernel-hardening] " Kees Cook
2017-02-08 4:29 ` John Stultz
2017-02-08 4:29 ` [kernel-hardening] " John Stultz
2017-02-08 10:24 ` Thomas Gleixner
2017-02-08 10:24 ` [kernel-hardening] " Thomas Gleixner
2017-02-08 18:09 ` John Stultz [this message]
2017-02-08 18:09 ` John Stultz
2017-02-08 4:41 ` kbuild test robot
2017-02-08 4:41 ` [kernel-hardening] " kbuild test robot
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