From d505b8af58912ae1e1a211fabc9995b19bd40828 Mon Sep 17 00:00:00 2001 From: Huaixin Chang Date: Sat, 25 Apr 2020 18:52:48 +0800 Subject: sched: Defend cfs and rt bandwidth quota against overflow When users write some huge number into cpu.cfs_quota_us or cpu.rt_runtime_us, overflow might happen during to_ratio() shifts of schedulable checks. to_ratio() could be altered to avoid unnecessary internal overflow, but min_cfs_quota_period is less than 1 << BW_SHIFT, so a cutoff would still be needed. Set a cap MAX_BW for cfs_quota_us and rt_runtime_us to prevent overflow. Signed-off-by: Huaixin Chang Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Ben Segall Link: https://lkml.kernel.org/r/20200425105248.60093-1-changhuaixin@linux.alibaba.com --- kernel/sched/sched.h | 2 ++ 1 file changed, 2 insertions(+) (limited to 'kernel/sched/sched.h') diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h index 2bd2a222318a..f7ab6334e992 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -1915,6 +1915,8 @@ extern void init_dl_inactive_task_timer(struct sched_dl_entity *dl_se); #define BW_SHIFT 20 #define BW_UNIT (1 << BW_SHIFT) #define RATIO_SHIFT 8 +#define MAX_BW_BITS (64 - BW_SHIFT) +#define MAX_BW ((1ULL << MAX_BW_BITS) - 1) unsigned long to_ratio(u64 period, u64 runtime); extern void init_entity_runnable_average(struct sched_entity *se); -- cgit v1.2.3-59-g8ed1b