From 69895c5ea0ca2e8d7de1e6d36965d0ab9730787f Mon Sep 17 00:00:00 2001
From: Herbert Xu <herbert@gondor.apana.org.au>
Date: Fri, 15 Dec 2017 16:40:44 +1100
Subject: [PATCH] xfrm: Reinject transport-mode packets through tasklet

commit acf568ee859f098279eadf551612f103afdacb4e upstream.

This is an old bugbear of mine:

https://www.mail-archive.com/netdev@vger.kernel.org/msg03894.html

By crafting special packets, it is possible to cause recursion
in our kernel when processing transport-mode packets at levels
that are only limited by packet size.

The easiest one is with DNAT, but an even worse one is where
UDP encapsulation is used in which case you just have to insert
an UDP encapsulation header in between each level of recursion.

This patch avoids this problem by reinjecting tranport-mode packets
through a tasklet.

Fixes: b05e106698d9 ("[IPV4/6]: Netfilter IPsec input hooks")
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
[bwh: Backported to 3.2:
 - netfilter finish callbacks only receive an sk_buff pointer
 - Adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
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