From bdfc87f7d1e253e0a61e2fc6a75ea9d76f7fc03a Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Tue, 11 Sep 2012 13:11:12 +0000 Subject: [PATCH] net-sched: sch_cbq: avoid infinite loop Its possible to setup a bad cbq configuration leading to an infinite loop in cbq_classify() DEV_OUT=eth0 ICMP="match ip protocol 1 0xff" U32="protocol ip u32" DST="match ip dst" tc qdisc add dev $DEV_OUT root handle 1: cbq avpkt 1000 \ bandwidth 100mbit tc class add dev $DEV_OUT parent 1: classid 1:1 cbq \ rate 512kbit allot 1500 prio 5 bounded isolated tc filter add dev $DEV_OUT parent 1: prio 3 $U32 \ $ICMP $DST 192.168.3.234 flowid 1: Reported-by: Denys Fedoryschenko Tested-by: Denys Fedoryschenko Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller --- net/sched/sch_cbq.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/net/sched/sch_cbq.c b/net/sched/sch_cbq.c index 6aabd77d1cf..564b9fc8efd 100644 --- a/net/sched/sch_cbq.c +++ b/net/sched/sch_cbq.c @@ -250,10 +250,11 @@ cbq_classify(struct sk_buff *skb, struct Qdisc *sch, int *qerr) else if ((cl = defmap[res.classid & TC_PRIO_MAX]) == NULL) cl = defmap[TC_PRIO_BESTEFFORT]; - if (cl == NULL || cl->level >= head->level) + if (cl == NULL) goto fallback; } - + if (cl->level >= head->level) + goto fallback; #ifdef CONFIG_NET_CLS_ACT switch (result) { case TC_ACT_QUEUED: -- 2.20.1