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net-sched: sch_cbq: avoid infinite loop

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[ Upstream commit bdfc87f7d1 ]

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 <denys@visp.net.lb>
Tested-by: Denys Fedoryschenko <denys@visp.net.lb>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Eric Dumazet
2012-09-11 13:11:12 +00:00
committed by Greg Kroah-Hartman
parent b89ea13784
commit 829f2161f7
1 changed files with 3 additions and 2 deletions
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5
net/sched/sch_cbq.c
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@@ -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: