Patchwork [-stable-3.9,11/15] netfilter: xt_TCPMSS: Fix missing fragmentation handling

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Submitter Pablo Neira
Date July 2, 2013, 2:51 p.m.
Message ID <1372776665-6795-11-git-send-email-pablo@netfilter.org>
Download mbox | patch
Permalink /patch/256441/
State Awaiting Upstream
Headers show

Comments

Pablo Neira - July 2, 2013, 2:51 p.m.
From: Phil Oester <kernel@linuxace.com>

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>
---
Cherry-pick: b396966c4688522863572927cb30aa874b3ec504

 net/netfilter/xt_TCPMSS.c |    4 ++++
 1 file changed, 4 insertions(+)

Patch

diff --git a/net/netfilter/xt_TCPMSS.c b/net/netfilter/xt_TCPMSS.c
index 4960b66..a77d786 100644
--- a/net/netfilter/xt_TCPMSS.c
+++ b/net/netfilter/xt_TCPMSS.c
@@ -55,6 +55,10 @@  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;