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netem: fix a use after free 

If the packet was dropped by lower qdisc, then we must not
access it later.

Save qdisc_pkt_len(skb) in a temp variable.

Fixes: 2ccccf5fb4 ("net_sched: update hierarchical backlog too")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: WANG Cong <xiyou.wangcong@gmail.com>
Cc: Jamal Hadi Salim <jhs@mojatatu.com>
Cc: Stephen Hemminger <stephen@networkplumber.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet 2016-06-20 15:00:43 -07:00 committed by David S. Miller
parent 817e9f2c5c
commit 21de12ee55
1 changed files with 6 additions and 6 deletions
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12
net/sched/sch_netem.c
View File

@ -650,14 +650,14 @@ static struct sk_buff *netem_dequeue(struct Qdisc *sch)
#endif
if (q->qdisc) {
unsigned int pkt_len = qdisc_pkt_len(skb);
int err = qdisc_enqueue(skb, q->qdisc);
if (unlikely(err != NET_XMIT_SUCCESS)) {
if (net_xmit_drop_count(err)) {
qdisc_qstats_drop(sch);
qdisc_tree_reduce_backlog(sch, 1,
qdisc_pkt_len(skb));
}
if (err != NET_XMIT_SUCCESS &&
net_xmit_drop_count(err)) {
qdisc_qstats_drop(sch);
qdisc_tree_reduce_backlog(sch, 1,
pkt_len);
}
goto tfifo_dequeue;
}