[PATCH 4.9 065/128] sched/core: Check quota and period overflow at usec to nsec conversion

From: Greg Kroah-Hartman
Date: Wed May 29 2019 - 23:33:20 EST


[ Upstream commit 1a8b4540db732ca16c9e43ac7c08b1b8f0b252d8 ]

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@xxxxxxxxxxxxxx>
Acked-by: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Link: http://lkml.kernel.org/r/155125502079.293431.3947497929372138600.stgit@buzz
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
kernel/sched/core.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 50e80b1be2c8f..4617ede80f020 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -8611,8 +8611,10 @@ 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);
}
@@ -8634,6 +8636,9 @@ 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;

--
2.20.1