sched/core: Check quota and period overflow at usec to nsec conversion

Large values could overflow u64 and pass following sanity checks.

 # echo 18446744073750000 > cpu.cfs_period_us
 # cat cpu.cfs_period_us
 40448

 # echo 18446744073750000 > cpu.cfs_quota_us
 # cat cpu.cfs_quota_us
 40448

After this patch they will fail with -EINVAL.

Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/155125502079.293431.3947497929372138600.stgit@buzz
Signed-off-by: Ingo Molnar <mingo@kernel.org>

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 685b154..de8ab41 100644 (file)
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -6611,8 +6611,10 @@ static int tg_set_cfs_quota(struct task_group *tg, long cfs_quota_us)
        period = ktime_to_ns(tg->cfs_bandwidth.period);
        if (cfs_quota_us < 0)
                quota = RUNTIME_INF;
-       else
+       else if ((u64)cfs_quota_us <= U64_MAX / NSEC_PER_USEC)
                quota = (u64)cfs_quota_us * NSEC_PER_USEC;
+       else
+               return -EINVAL;
 
        return tg_set_cfs_bandwidth(tg, period, quota);
 }
@@ -6634,6 +6636,9 @@ static int tg_set_cfs_period(struct task_group *tg, long cfs_period_us)
 {
        u64 quota, period;
 
+       if ((u64)cfs_period_us > U64_MAX / NSEC_PER_USEC)
+               return -EINVAL;
+
        period = (u64)cfs_period_us * NSEC_PER_USEC;
        quota = tg->cfs_bandwidth.quota;