diff options
author | Huaixin Chang <changhuaixin@linux.alibaba.com> | 2020-04-25 18:52:48 +0800 |
---|---|---|
committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2020-06-22 09:31:07 +0200 |
commit | 9fa3b0bd9914133cf362a1719af522fa3fddee1e (patch) | |
tree | 7de697fdab6566cc33097ad0b3a9bd9ed6964fc4 /kernel/sched | |
parent | fecf17b609a7edc68c6ef8fa4750d2e75223a6b4 (diff) |
sched: Defend cfs and rt bandwidth quota against overflow
[ Upstream commit d505b8af58912ae1e1a211fabc9995b19bd40828 ]
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 <changhuaixin@linux.alibaba.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Ben Segall <bsegall@google.com>
Link: https://lkml.kernel.org/r/20200425105248.60093-1-changhuaixin@linux.alibaba.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'kernel/sched')
-rw-r--r-- | kernel/sched/core.c | 8 | ||||
-rw-r--r-- | kernel/sched/rt.c | 12 | ||||
-rw-r--r-- | kernel/sched/sched.h | 2 |
3 files changed, 21 insertions, 1 deletions
diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 4874e1468279..361cbc2dc966 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -7374,6 +7374,8 @@ static DEFINE_MUTEX(cfs_constraints_mutex); const u64 max_cfs_quota_period = 1 * NSEC_PER_SEC; /* 1s */ static const u64 min_cfs_quota_period = 1 * NSEC_PER_MSEC; /* 1ms */ +/* More than 203 days if BW_SHIFT equals 20. */ +static const u64 max_cfs_runtime = MAX_BW * NSEC_PER_USEC; static int __cfs_schedulable(struct task_group *tg, u64 period, u64 runtime); @@ -7402,6 +7404,12 @@ static int tg_set_cfs_bandwidth(struct task_group *tg, u64 period, u64 quota) return -EINVAL; /* + * Bound quota to defend quota against overflow during bandwidth shift. + */ + if (quota != RUNTIME_INF && quota > max_cfs_runtime) + return -EINVAL; + + /* * Prevent race between setting of cfs_rq->runtime_enabled and * unthrottle_offline_cfs_rqs(). */ diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c index 7bf917e4d63a..5b04bba4500d 100644 --- a/kernel/sched/rt.c +++ b/kernel/sched/rt.c @@ -9,6 +9,8 @@ int sched_rr_timeslice = RR_TIMESLICE; int sysctl_sched_rr_timeslice = (MSEC_PER_SEC / HZ) * RR_TIMESLICE; +/* More than 4 hours if BW_SHIFT equals 20. */ +static const u64 max_rt_runtime = MAX_BW; static int do_sched_rt_period_timer(struct rt_bandwidth *rt_b, int overrun); @@ -2513,6 +2515,12 @@ static int tg_set_rt_bandwidth(struct task_group *tg, if (rt_period == 0) return -EINVAL; + /* + * Bound quota to defend quota against overflow during bandwidth shift. + */ + if (rt_runtime != RUNTIME_INF && rt_runtime > max_rt_runtime) + return -EINVAL; + mutex_lock(&rt_constraints_mutex); read_lock(&tasklist_lock); err = __rt_schedulable(tg, rt_period, rt_runtime); @@ -2634,7 +2642,9 @@ static int sched_rt_global_validate(void) return -EINVAL; if ((sysctl_sched_rt_runtime != RUNTIME_INF) && - (sysctl_sched_rt_runtime > sysctl_sched_rt_period)) + ((sysctl_sched_rt_runtime > sysctl_sched_rt_period) || + ((u64)sysctl_sched_rt_runtime * + NSEC_PER_USEC > max_rt_runtime))) return -EINVAL; return 0; diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h index c7e7481968bf..570659f1c6e2 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -1889,6 +1889,8 @@ extern void init_dl_rq_bw_ratio(struct dl_rq *dl_rq); #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); |