* [PATCH v2 net] net: sched: taprio: Fix potential integer overflow in taprio_set_picos_per_byte
@ 2019-09-28 23:01 Vladimir Oltean
2019-09-30 17:19 ` Vinicius Costa Gomes
2019-10-01 1:33 ` David Miller
0 siblings, 2 replies; 3+ messages in thread
From: Vladimir Oltean @ 2019-09-28 23:01 UTC (permalink / raw)
To: davem, vinicius.gomes; +Cc: jhs, xiyou.wangcong, netdev, Vladimir Oltean
The speed divisor is used in a context expecting an s64, but it is
evaluated using 32-bit arithmetic.
To avoid that happening, instead of multiplying by 1,000,000 in the
first place, simplify the fraction and do a standard 32 bit division
instead.
Fixes: f04b514c0ce2 ("taprio: Set default link speed to 10 Mbps in taprio_set_picos_per_byte")
Reported-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Suggested-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: Vladimir Oltean <olteanv@gmail.com>
---
net/sched/sch_taprio.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)
diff --git a/net/sched/sch_taprio.c b/net/sched/sch_taprio.c
index 2f7b34205c82..2aab46ada94f 100644
--- a/net/sched/sch_taprio.c
+++ b/net/sched/sch_taprio.c
@@ -1048,8 +1048,7 @@ static void taprio_set_picos_per_byte(struct net_device *dev,
speed = ecmd.base.speed;
skip:
- picos_per_byte = div64_s64(NSEC_PER_SEC * 1000LL * 8,
- speed * 1000 * 1000);
+ picos_per_byte = (USEC_PER_SEC * 8) / speed;
atomic64_set(&q->picos_per_byte, picos_per_byte);
netdev_dbg(dev, "taprio: set %s's picos_per_byte to: %lld, linkspeed: %d\n",
--
2.17.1
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH v2 net] net: sched: taprio: Fix potential integer overflow in taprio_set_picos_per_byte
2019-09-28 23:01 [PATCH v2 net] net: sched: taprio: Fix potential integer overflow in taprio_set_picos_per_byte Vladimir Oltean
@ 2019-09-30 17:19 ` Vinicius Costa Gomes
2019-10-01 1:33 ` David Miller
1 sibling, 0 replies; 3+ messages in thread
From: Vinicius Costa Gomes @ 2019-09-30 17:19 UTC (permalink / raw)
To: Vladimir Oltean, davem; +Cc: jhs, xiyou.wangcong, netdev, Vladimir Oltean
Vladimir Oltean <olteanv@gmail.com> writes:
> The speed divisor is used in a context expecting an s64, but it is
> evaluated using 32-bit arithmetic.
>
> To avoid that happening, instead of multiplying by 1,000,000 in the
> first place, simplify the fraction and do a standard 32 bit division
> instead.
>
> Fixes: f04b514c0ce2 ("taprio: Set default link speed to 10 Mbps in taprio_set_picos_per_byte")
> Reported-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
> Suggested-by: Eric Dumazet <eric.dumazet@gmail.com>
> Signed-off-by: Vladimir Oltean <olteanv@gmail.com>
> ---
Acked-by: Vinicius Costa Gomes <vinicius.gomes@intel.com>
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH v2 net] net: sched: taprio: Fix potential integer overflow in taprio_set_picos_per_byte
2019-09-28 23:01 [PATCH v2 net] net: sched: taprio: Fix potential integer overflow in taprio_set_picos_per_byte Vladimir Oltean
2019-09-30 17:19 ` Vinicius Costa Gomes
@ 2019-10-01 1:33 ` David Miller
1 sibling, 0 replies; 3+ messages in thread
From: David Miller @ 2019-10-01 1:33 UTC (permalink / raw)
To: olteanv; +Cc: vinicius.gomes, jhs, xiyou.wangcong, netdev
From: Vladimir Oltean <olteanv@gmail.com>
Date: Sun, 29 Sep 2019 02:01:39 +0300
> The speed divisor is used in a context expecting an s64, but it is
> evaluated using 32-bit arithmetic.
>
> To avoid that happening, instead of multiplying by 1,000,000 in the
> first place, simplify the fraction and do a standard 32 bit division
> instead.
>
> Fixes: f04b514c0ce2 ("taprio: Set default link speed to 10 Mbps in taprio_set_picos_per_byte")
> Reported-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
> Suggested-by: Eric Dumazet <eric.dumazet@gmail.com>
> Signed-off-by: Vladimir Oltean <olteanv@gmail.com>
Applied and queued up for -stable, thanks.
^ permalink raw reply [flat|nested] 3+ messages in thread
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2019-09-30 17:19 ` Vinicius Costa Gomes
2019-10-01 1:33 ` David Miller
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