diff options
| author | Huaixin Chang <changhuaixin@linux.alibaba.com> | 2020-04-25 13:52:48 +0300 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2020-05-19 21:34:14 +0300 |
| commit | d505b8af58912ae1e1a211fabc9995b19bd40828 (patch) | |
| tree | d3eb4c4bd5d8670ee6aaaa56993a8ed366160de7 /kernel/sched/rt.c | |
| parent | dbe9337109c2705f08e6a00392f991eb2d2570a5 (diff) | |
| download | linux-d505b8af58912ae1e1a211fabc9995b19bd40828.tar.xz | |
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 <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
Diffstat (limited to 'kernel/sched/rt.c')
| -rw-r--r-- | kernel/sched/rt.c | 12 |
1 files changed, 11 insertions, 1 deletions
diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c index df11d88c9895..6d60ba21ed29 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); @@ -2585,6 +2587,12 @@ 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); err = __rt_schedulable(tg, rt_period, rt_runtime); if (err) @@ -2702,7 +2710,9 @@ 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; |