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| author | Quentin Perret <qperret@google.com> | 2021-04-30 17:14:12 +0200 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2021-05-06 15:33:26 +0200 |
| commit | 6d2f8909a5fabb73fe2a63918117943986c39b6c (patch) | |
| tree | 7046c225d90183e5bd49a00a15a95cf703c37716 | |
| parent | psi: Fix psi state corruption when schedule() races with cgroup move (diff) | |
| download | linux-6d2f8909a5fabb73fe2a63918117943986c39b6c.tar.xz linux-6d2f8909a5fabb73fe2a63918117943986c39b6c.zip | |
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
| -rw-r--r-- | kernel/sched/core.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 9143163fa678..5226cc26a095 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -938,7 +938,7 @@ DEFINE_STATIC_KEY_FALSE(sched_uclamp_used); static inline unsigned int uclamp_bucket_id(unsigned int clamp_value) { - return clamp_value / UCLAMP_BUCKET_DELTA; + return min_t(unsigned int, clamp_value / UCLAMP_BUCKET_DELTA, UCLAMP_BUCKETS - 1); } static inline unsigned int uclamp_none(enum uclamp_id clamp_id) |