| From | Ben Hutchings <> | Date | Sat, 13 Aug 2016 18:42:51 +0100 | Subject | [PATCH 3.16 192/305] netem: fix a use after free |
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3.16.37-rc1 review patch. If anyone has any objections, please let me know.
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From: Eric Dumazet <edumazet@google.com>
commit 21de12ee5568fd1aec47890c72967abf791ac80a upstream.
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 <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> [bwh: Backported to 3.16: not using qdisc_qstats_drop()] Signed-off-by: Ben Hutchings <ben@decadent.org.uk> --- net/sched/sch_netem.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-)
--- a/net/sched/sch_netem.c +++ b/net/sched/sch_netem.c @@ -606,14 +606,14 @@ 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)) { - sch->qstats.drops++; - qdisc_tree_reduce_backlog(sch, 1, - qdisc_pkt_len(skb)); - } + if (err != NET_XMIT_SUCCESS && + net_xmit_drop_count(err)) { + sch->qstats.drops++; + qdisc_tree_reduce_backlog(sch, 1, + pkt_len); } goto tfifo_dequeue; }
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