net: sched: cbs: Avoid division by zero when calculating the port rate

[ Upstream commit 83c8c3cf45163f0c823db37be6ab04dfcf8ac751 ]

As explained in the "net: sched: taprio: Avoid division by zero on
invalid link speed" commit, it is legal for the ethtool API to return
zero as a link speed. So guard against it to ensure we don't perform a
division by zero in kernel.

Fixes: e0a7683d30e9 ("net/sched: cbs: fix port_rate miscalculation")
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>

diff --git a/net/sched/sch_cbs.c b/net/sched/sch_cbs.c
index 4a403d35438f6439c390674fae8bca30139b0dd9..284ab2dcf47fb37710392fc397bafb0b471c0bb0 100644 (file)
--- a/net/sched/sch_cbs.c
+++ b/net/sched/sch_cbs.c
@@ -306,7 +306,7 @@ static void cbs_set_port_rate(struct net_device *dev, struct cbs_sched_data *q)
        if (err < 0)
                goto skip;
 
-       if (ecmd.base.speed != SPEED_UNKNOWN)
+       if (ecmd.base.speed && ecmd.base.speed != SPEED_UNKNOWN)
                speed = ecmd.base.speed;
 
 skip: