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netfilter: xt_TCPOPTSTRIP: don't use tcp_hdr()

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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>
This commit is contained in:
Pablo Neira Ayuso 2013-06-11 01:51:31 +02:00
parent a8241c6351
commit ed82c43732
1 changed files with 4 additions and 2 deletions
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6
net/netfilter/xt_TCPOPTSTRIP.c
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@ -48,11 +48,13 @@ tcpoptstrip_mangle_packet(struct sk_buff *skb,
return NF_DROP;
len = skb->len - tcphoff;
if (len < (int)sizeof(struct tcphdr) ||
tcp_hdr(skb)->doff * 4 > len)
if (len < (int)sizeof(struct tcphdr))
return NF_DROP;
tcph = (struct tcphdr *)(skb_network_header(skb) + tcphoff);
if (tcph->doff * 4 > len)
return NF_DROP;
opt = (u_int8_t *)tcph;
/*