[PATCH 1/3] sched/rt: check integer overflow at usec to nsec conversion

[Konstantin Khlebnikov <khlebnikov@yandex-team.ru>]

Example of unhandled overflows:

# echo 18446744073709651 > cpu.rt_runtime_us
# cat cpu.rt_runtime_us
99

# echo 18446744073709900 > cpu.rt_period_us
# cat cpu.rt_period_us
348

After this patch they will fail with -EINVAL.

Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
---
 kernel/sched/rt.c |    5 +++++
 1 file changed, 5 insertions(+)

diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c
index e4f398ad9e73..aa7ee3a0bf90 100644
--- a/kernel/sched/rt.c
+++ b/kernel/sched/rt.c
@@ -2555,6 +2555,8 @@ int sched_group_set_rt_runtime(struct task_group *tg, long rt_runtime_us)
 	rt_runtime = (u64)rt_runtime_us * NSEC_PER_USEC;
 	if (rt_runtime_us < 0)
 		rt_runtime = RUNTIME_INF;
+	else if ((u64)rt_runtime_us > U64_MAX / NSEC_PER_USEC)
+		return -EINVAL;
 
 	return tg_set_rt_bandwidth(tg, rt_period, rt_runtime);
 }
@@ -2575,6 +2577,9 @@ int sched_group_set_rt_period(struct task_group *tg, u64 rt_period_us)
 {
 	u64 rt_runtime, rt_period;
 
+	if (rt_period_us > U64_MAX / NSEC_PER_USEC)
+		return -EINVAL;
+
 	rt_period = rt_period_us * NSEC_PER_USEC;
 	rt_runtime = tg->rt_bandwidth.rt_runtime;