Messages in this thread | | | Date | Mon, 3 May 2021 16:45:16 +0200 | From | Peter Zijlstra <> | Subject | Re: [PATCH v3] sched: Fix out-of-bound access in uclamp |
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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!
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