| From | Greg Kroah-Hartman <> | Subject | [PATCH 5.3 135/166] net: sched: taprio: Fix potential integer overflow in taprio_set_picos_per_byte | Date | Sun, 6 Oct 2019 19:21:41 +0200 |
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From: Vladimir Oltean <olteanv@gmail.com>
[ Upstream commit 68ce6688a5baefde30914fc07fc27292dbbe8320 ]
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> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> --- net/sched/sch_taprio.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-)
--- a/net/sched/sch_taprio.c +++ b/net/sched/sch_taprio.c @@ -965,8 +965,7 @@ static void taprio_set_picos_per_byte(st 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",
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