From mboxrd@z Thu Jan  1 00:00:00 1970
From: David Miller <davem@davemloft.net>
Subject: Re: [PATCH net] ip6_tunnel: be careful when accessing the inner
 header
Date: Wed, 19 Sep 2018 21:25:04 -0700 (PDT)
Message-ID: <20180919.212504.1074082892099388965.davem@davemloft.net>
References: <78ef06b7731007ff16b00962c58f36f87d689d65.1537362057.git.pabeni@redhat.com>
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To: pabeni@redhat.com
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From: Paolo Abeni <pabeni@redhat.com>
Date: Wed, 19 Sep 2018 15:02:07 +0200

> the ip6 tunnel xmit ndo assumes that the processed skb always
> contains an ip[v6] header, but syzbot has found a way to send
> frames that fall short of this assumption, leading to the following splat:
 ...
> This change addresses the issue adding the needed check before
> accessing the inner header.
> 
> The ipv4 side of the issue is apparently there since the ipv4 over ipv6
> initial support, and the ipv6 side predates git history.
> 
> Fixes: c4d3efafcc93 ("[IPV6] IP6TUNNEL: Add support to IPv4 over IPv6 tunnel.")
> Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
> Reported-by: syzbot+3fde91d4d394747d6db4@syzkaller.appspotmail.com
> Tested-by: Alexander Potapenko <glider@google.com>
> Signed-off-by: Paolo Abeni <pabeni@redhat.com>

Applied and queued up for -stable.