From aea92fb2e09e29653b023d4254ac9fbf94221538 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Fri, 17 Mar 2017 08:05:28 -0700 Subject: [PATCH] sch_dsmark: fix invalid skb_cow() usage skb_cow(skb, sizeof(ip header)) is not very helpful in this context. First we need to use pskb_may_pull() to make sure the ip header is in skb linear part, then use skb_try_make_writable() to address clones issues. Fixes: 4c30719f4f55 ("[PKT_SCHED] dsmark: handle cloned and non-linear skb's") Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller --- net/sched/sch_dsmark.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) diff --git a/net/sched/sch_dsmark.c b/net/sched/sch_dsmark.c index 802ac7c2e5e8..5334e309f17f 100644 --- a/net/sched/sch_dsmark.c +++ b/net/sched/sch_dsmark.c @@ -201,9 +201,13 @@ static int dsmark_enqueue(struct sk_buff *skb, struct Qdisc *sch, pr_debug("%s(skb %p,sch %p,[qdisc %p])\n", __func__, skb, sch, p); if (p->set_tc_index) { + int wlen = skb_network_offset(skb); + switch (tc_skb_protocol(skb)) { case htons(ETH_P_IP): - if (skb_cow_head(skb, sizeof(struct iphdr))) + wlen += sizeof(struct iphdr); + if (!pskb_may_pull(skb, wlen) || + skb_try_make_writable(skb, wlen)) goto drop; skb->tc_index = ipv4_get_dsfield(ip_hdr(skb)) @@ -211,7 +215,9 @@ static int dsmark_enqueue(struct sk_buff *skb, struct Qdisc *sch, break; case htons(ETH_P_IPV6): - if (skb_cow_head(skb, sizeof(struct ipv6hdr))) + wlen += sizeof(struct ipv6hdr); + if (!pskb_may_pull(skb, wlen) || + skb_try_make_writable(skb, wlen)) goto drop; skb->tc_index = ipv6_get_dsfield(ipv6_hdr(skb)) -- 2.20.1