diff options
| author | Quentin Perret <qperret@google.com> | 2021-04-30 15:14:12 +0000 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2021-05-19 10:13:09 +0200 |
| commit | f7347c85490b92dd144fa1fba9e1eca501656ab3 (patch) | |
| tree | 77dcf659f3a0dd918a9d3c9db66b245271824746 /kernel | |
| parent | 26359d362c93bdca3038f7f70d28d5ed46222a03 (diff) | |
sched: Fix out-of-bound access in uclamp
[ Upstream commit 6d2f8909a5fabb73fe2a63918117943986c39b6c ]
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
Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'kernel')
| -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 3c3554d9ee50..57b236251884 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -936,7 +936,7 @@ 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) |