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Date: Wed, 25 Mar 2026 18:28:58 +0100
From: Florian Westphal <fw@strlen.de>
To: Pablo Neira Ayuso <pablo@netfilter.org>
Cc: netdev@vger.kernel.org, Paolo Abeni <pabeni@redhat.com>,
	"David S. Miller" <davem@davemloft.net>,
	Eric Dumazet <edumazet@google.com>,
	Jakub Kicinski <kuba@kernel.org>, netfilter-devel@vger.kernel.org
Subject: Re: [PATCH net 10/14] netfilter: ctnetlink: ensure safe access to
 master conntrack
Message-ID: <acQbWvJUK20gbTWg@strlen.de>
References: <20260325131108.23045-1-fw@strlen.de>
 <20260325131108.23045-11-fw@strlen.de>
 <acQa30IdYh3PeLAh@chamomile>
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In-Reply-To: <acQa30IdYh3PeLAh@chamomile>

Pablo Neira Ayuso <pablo@netfilter.org> wrote:
> Sorry for this late followup incremental fix.

I'm tired.

> diff --git a/net/netfilter/nf_conntrack_expect.c b/net/netfilter/nf_conntrack_expect.c
> index 509d3eb6f56a..cf39662c4b97 100644
> --- a/net/netfilter/nf_conntrack_expect.c
> +++ b/net/netfilter/nf_conntrack_expect.c
> @@ -325,7 +325,9 @@ void nf_ct_expect_init(struct nf_conntrack_expect *exp, unsigned int class,
>  		       u_int8_t proto, const __be16 *src, const __be16 *dst)
>  {
>  	struct net *net = read_pnet(&exp->master->ct_net);
> -
> +	struct nf_conntrack_helper *helper;
> +	struct nf_conn *ct = exp->master;
> +	struct nf_conn_help *help;
>  	int len;
>  
>  	if (family == AF_INET)
> @@ -336,7 +338,14 @@ void nf_ct_expect_init(struct nf_conntrack_expect *exp, unsigned int class,
>  	exp->flags = 0;
>  	exp->class = class;
>  	exp->expectfn = NULL;
> -	rcu_assign_pointer(exp->helper, nfct_help(exp->master)->helper);
> +	help = nfct_help(ct);

Do we have a reference here? Is that safe?

I'm not looking forward to a new PR.