netfilter: xt_TCPOPTSTRIP: don't use tcp_hdr()
In (bc6bcb5
netfilter: xt_TCPOPTSTRIP: fix possible mangling beyond
packet boundary), the use of tcp_hdr was introduced. However, we
cannot assume that skb->transport_header is set for non-local packets.
Cc: Florian Westphal <fw@strlen.de>
Reported-by: Phil Oester <kernel@linuxace.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
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@ -48,11 +48,13 @@ tcpoptstrip_mangle_packet(struct sk_buff *skb,
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return NF_DROP;
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len = skb->len - tcphoff;
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if (len < (int)sizeof(struct tcphdr) ||
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tcp_hdr(skb)->doff * 4 > len)
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if (len < (int)sizeof(struct tcphdr))
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return NF_DROP;
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tcph = (struct tcphdr *)(skb_network_header(skb) + tcphoff);
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if (tcph->doff * 4 > len)
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return NF_DROP;
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opt = (u_int8_t *)tcph;
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/*
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