| From | Ben Hutchings <> | Date | Sun, 11 Feb 2018 04:20:06 +0000 | Subject | [PATCH 3.2 62/79] netfilter: xt_TCPOPTSTRIP: don't use tcp_hdr() |
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3.2.99-rc1 review patch. If anyone has any objections, please let me know.
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From: Pablo Neira Ayuso <pablo@netfilter.org>
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@strlen.de> Reported-by: Phil Oester <kernel@linuxace.com> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org> Signed-off-by: Ben Hutchings <ben@decadent.org.uk> --- net/netfilter/xt_TCPOPTSTRIP.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-)
--- a/net/netfilter/xt_TCPOPTSTRIP.c +++ b/net/netfilter/xt_TCPOPTSTRIP.c @@ -48,11 +48,13 @@ tcpoptstrip_mangle_packet(struct sk_buff 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; /*
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