From d940902921d277f53338dddd5068840893e9b372 Mon Sep 17 00:00:00 2001
From: Eric Dumazet <edumazet@google.com>
Date: Fri, 17 Mar 2017 08:05:28 -0700
Subject: [PATCH] sch_dsmark: fix invalid skb_cow() usage

commit aea92fb2e09e29653b023d4254ac9fbf94221538 upstream.

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 <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
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