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From: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
To: Peter Zijlstra <peterz@infradead.org>,
	Ingo Molnar <mingo@redhat.com>,
	linux-kernel@vger.kernel.org
Subject: [PATCH 3/3] sched/core: check quota and period overflow at usec to nsec conversion
Date: Wed, 27 Feb 2019 11:10:20 +0300
Message-ID: <155125502079.293431.3947497929372138600.stgit@buzz> (raw)
In-Reply-To: <155125501739.293431.5252197504404771496.stgit@buzz>

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>
---
 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 a626fbd9fdc7..5f46aa335b28 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -6606,8 +6606,10 @@ 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);
 }
@@ -6629,6 +6631,9 @@ 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;
 


  parent reply index

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-02-27  8:10 [PATCH 1/3] sched/rt: check integer " Konstantin Khlebnikov
2019-02-27  8:10 ` [PATCH 2/3] sched/core: handle overflow in cpu_shares_write_u64 Konstantin Khlebnikov
2019-04-19 12:16   ` [tip:sched/core] sched/core: Handle " tip-bot for Konstantin Khlebnikov
2019-02-27  8:10 ` Konstantin Khlebnikov [this message]
2019-04-19 12:17   ` [tip:sched/core] sched/core: Check quota and period overflow at usec to nsec conversion tip-bot for Konstantin Khlebnikov
2019-04-19 12:16 ` [tip:sched/core] sched/rt: Check integer " tip-bot for Konstantin Khlebnikov

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