From: Peter Zijlstra <peterz@infradead.org>
To: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>,
Quentin Perret <qperret@google.com>,
Ingo Molnar <mingo@redhat.com>,
Juri Lelli <juri.lelli@redhat.com>,
Steven Rostedt <rostedt@goodmis.org>,
Ben Segall <bsegall@google.com>, Mel Gorman <mgorman@suse.de>,
Daniel Bristot de Oliveira <bristot@redhat.com>,
Qais Yousef <qais.yousef@arm.com>,
Android Kernel Team <kernel-team@android.com>,
linux-kernel <linux-kernel@vger.kernel.org>,
Patrick Bellasi <patrick.bellasi@matbug.net>
Subject: Re: [PATCH v3] sched: Fix out-of-bound access in uclamp
Date: Mon, 3 May 2021 16:45:16 +0200 [thread overview]
Message-ID: <YJAMfE/cV8zL4tHJ@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <562004ff-9f60-bf37-df4c-547415ae2cd5@arm.com>
On Mon, May 03, 2021 at 12:55:34PM +0200, Dietmar Eggemann wrote:
> On 30/04/2021 17:27, Vincent Guittot wrote:
> > On Fri, 30 Apr 2021 at 17:14, Quentin Perret <qperret@google.com> wrote:
> >>
> >> Util-clamp places tasks in different buckets based on their clamp values
> >> for performance reasons. However, the size of buckets is currently
> >> computed using a rounding division, which can lead to an off-by-one
> >> error in some configurations.
> >>
> >> For instance, with 20 buckets, the bucket size will be 1024/20=51. A
> >> task with a clamp of 1024 will be mapped to bucket id 1024/51=20. Sadly,
> >> correct indexes are in range [0,19], hence leading to an out of bound
> >> memory access.
> >>
> >> Clamp the bucket id to fix the issue.
> >>
> >> Fixes: 69842cba9ace ("sched/uclamp: Add CPU's clamp buckets refcounting")
> >> Suggested-by: Qais Yousef <qais.yousef@arm.com>
> >> Signed-off-by: Quentin Perret <qperret@google.com>
> >
> > Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
> Reviewed-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Thanks!
next prev parent reply other threads:[~2021-05-03 14:47 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-30 15:14 Quentin Perret
2021-04-30 15:27 ` Vincent Guittot
2021-05-03 10:55 ` Dietmar Eggemann
2021-05-03 14:45 ` Peter Zijlstra [this message]
2021-05-06 13:48 ` [tip: sched/urgent] " tip-bot2 for Quentin Perret
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