[PATCH net] netem: fix a use after free
From: Eric Dumazet <hidden>
Date: 2016-06-20 22:58:13
Subsystem:
netem network emulator, networking [general], tc subsystem, the rest · Maintainers:
Stephen Hemminger, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Jamal Hadi Salim, Jiri Pirko, Linus Torvalds
From: Eric Dumazet <edumazet@google.com>
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: 2ccccf5fb43f ("net_sched: update hierarchical backlog too")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: WANG Cong <redacted>
Cc: Jamal Hadi Salim <jhs@mojatatu.com>
Cc: Stephen Hemminger <stephen@networkplumber.org>
---
net/sched/sch_netem.c | 12 ++++++------
1 file changed, 6 insertions(+), 6 deletions(-)
diff --git a/net/sched/sch_netem.c b/net/sched/sch_netem.c
index 205bed00dd34..178f1630a036 100644
--- a/net/sched/sch_netem.c
+++ b/net/sched/sch_netem.c@@ -650,14 +650,14 @@ deliver: #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; }