[PATCH 080/145] netfilter: xt_TCPOPTSTRIP: don't use tcp_hdr()

From: Kamal Mostafa
Date: Wed Jul 17 2013 - 19:12:29 EST


3.8.13.5 -stable review patch. If anyone has any objections, please let me know.

------------------

From: Pablo Neira Ayuso <pablo@xxxxxxxxxxxxx>

commit ed82c437320c48a4032492f4a55a7e2c934158b6 upstream.

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@xxxxxxxxx>
Reported-by: Phil Oester <kernel@xxxxxxxxxxxx>
Signed-off-by: Pablo Neira Ayuso <pablo@xxxxxxxxxxxxx>
Signed-off-by: Luis Henriques <luis.henriques@xxxxxxxxxxxxx>
---
net/netfilter/xt_TCPOPTSTRIP.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/net/netfilter/xt_TCPOPTSTRIP.c b/net/netfilter/xt_TCPOPTSTRIP.c
index 1eb1a44..b68fa19 100644
--- a/net/netfilter/xt_TCPOPTSTRIP.c
+++ b/net/netfilter/xt_TCPOPTSTRIP.c
@@ -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;

/*
--
1.8.1.2

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