Quentin Perret 6d2f8909a5 sched: Fix out-of-bound access in uclamp
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>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Reviewed-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Link: https://lkml.kernel.org/r/20210430151412.160913-1-qperret@google.com
2021-05-06 15:33:26 +02:00
..
2021-04-27 13:42:11 -07:00
2021-04-27 18:09:44 -07:00
2021-04-26 09:41:15 -07:00
2021-04-22 14:36:03 +02:00
2021-04-27 18:14:38 -07:00
2021-04-08 19:37:21 +02:00
2021-03-24 12:11:48 -04:00
2021-04-27 13:50:58 -07:00
2021-04-08 16:04:20 -07:00
2021-04-28 14:56:09 -07:00
2021-03-29 15:56:48 +02:00
2021-04-08 16:04:20 -07:00
2021-04-08 16:04:20 -07:00
2020-12-14 16:40:27 -08:00
2020-11-14 11:26:04 -08:00
2020-12-17 13:01:31 -08:00
2020-12-14 16:40:27 -08:00
2021-04-20 10:13:58 +02:00
2020-07-27 14:31:12 -04:00
2020-12-01 10:30:28 +00:00
2021-04-28 13:33:57 -07:00
2021-01-22 15:09:42 +01:00
2021-04-28 12:00:13 -07:00
2021-03-17 15:51:17 +01:00
\n
2021-04-29 11:06:13 -07:00
2021-02-09 12:27:29 -05:00
2020-08-19 14:14:12 +02:00
2020-08-19 14:13:20 +02:00
2021-04-27 10:16:46 -07:00