pkt_sched: fq: avoid hang when quantum 0

Configuring fq with quantum 0 hangs the system, presumably because of a
non-interruptible infinite loop. Either way quantum 0 does not make sense.

Reproduce with:
sudo tc qdisc add dev lo root fq quantum 0 initial_quantum 0
ping 127.0.0.1

Signed-off-by: Kenneth Klette Jonassen <kennetkl@ifi.uio.no>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/sched/sch_fq.c b/net/sched/sch_fq.c
index 9b05924cc386ecc2cdb9816be27e439637fb37b3..333cd94ba381ff62f9512d6b95474a2aecc3ea88 100644 (file)
--- a/net/sched/sch_fq.c
+++ b/net/sched/sch_fq.c
@@ -670,8 +670,14 @@ static int fq_change(struct Qdisc *sch, struct nlattr *opt)
        if (tb[TCA_FQ_FLOW_PLIMIT])
                q->flow_plimit = nla_get_u32(tb[TCA_FQ_FLOW_PLIMIT]);
 
-       if (tb[TCA_FQ_QUANTUM])
-               q->quantum = nla_get_u32(tb[TCA_FQ_QUANTUM]);
+       if (tb[TCA_FQ_QUANTUM]) {
+               u32 quantum = nla_get_u32(tb[TCA_FQ_QUANTUM]);
+
+               if (quantum > 0)
+                       q->quantum = quantum;
+               else
+                       err = -EINVAL;
+       }
 
        if (tb[TCA_FQ_INITIAL_QUANTUM])
                q->initial_quantum = nla_get_u32(tb[TCA_FQ_INITIAL_QUANTUM]);