[PATCH 5.1 168/405] sched/core: Check quota and period overflow at usec to nsec conversion

[Greg Kroah-Hartman]

[ 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 4778c48a7fda4..89c9c1d7d22c5 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -6661,8 +6661,10 @@ 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);
 }
@@ -6684,6 +6686,9 @@ 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