From: Phil Oester <kernel@linuxace.com>
Date: Wed, 12 Jun 2013 08:58:20 +0000 (+0200)
Subject: netfilter: xt_TCPMSS: Fix missing fragmentation handling
X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=b396966c4688522863572927cb30aa874b3ec504;p=linux-beck.git

netfilter: xt_TCPMSS: Fix missing fragmentation handling

Similar to commit bc6bcb59 ("netfilter: xt_TCPOPTSTRIP: fix
possible mangling beyond packet boundary"), add safe fragment
handling to xt_TCPMSS.

Signed-off-by: Phil Oester <kernel@linuxace.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---

diff --git a/net/netfilter/xt_TCPMSS.c b/net/netfilter/xt_TCPMSS.c
index 6640a224f9fb..7011c71646f0 100644
--- a/net/netfilter/xt_TCPMSS.c
+++ b/net/netfilter/xt_TCPMSS.c
@@ -57,6 +57,10 @@ tcpmss_mangle_packet(struct sk_buff *skb,
 	u16 newmss;
 	u8 *opt;
 
+	/* This is a fragment, no TCP header is available */
+	if (par->fragoff != 0)
+		return XT_CONTINUE;
+
 	if (!skb_make_writable(skb, skb->len))
 		return -1;