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Date: Thu, 23 Jul 2026 10:09:49 -0700
From: Jakub Kicinski <kuba@kernel.org>
To: "Xiang Mei (Microsoft)" <xmei5@asu.edu>
Cc: Andrea Mayer <andrea.mayer@uniroma2.it>, "David S . Miller"
 <davem@davemloft.net>, Eric Dumazet <edumazet@google.com>, Paolo Abeni
 <pabeni@redhat.com>, Simon Horman <horms@kernel.org>,
 netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Pablo Neira Ayuso
 <pablo@netfilter.org>, Ryoga Saito <contact@proelbtn.com>,
 AutonomousCodeSecurity@microsoft.com, tgopinath@linux.microsoft.com,
 kys@microsoft.com
Subject: Re: [PATCH net] seg6: fix NULL deref in
 input_action_end_dx{4,6}_finish() after nf hook
Message-ID: <20260723100949.4443811e@kernel.org>
In-Reply-To: <20260720204430.1886091-1-xmei5@asu.edu>
References: <20260720204430.1886091-1-xmei5@asu.edu>
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On Mon, 20 Jul 2026 20:44:29 +0000 Xiang Mei (Microsoft) wrote:
> When nf_hooks_lwtunnel is enabled, the End.DX4/End.DX6 actions dispatch
> the decapsulated inner packet through the NF_INET_PRE_ROUTING hook chain
> with input_action_end_dx{4,6}_finish() as the okfn. Both functions read
> the lwtunnel state via orig_dst = skb_dst(skb) and dereference
> orig_dst->lwtstate.

Per Sashiko's feedback - we need to validate not only that the dst 
is there but also that it is of the expected type, no?
-- 
pw-bot: cr