From: Florian Westphal <fw@strlen.de>
To: Daehyeon Ko <4ncienth@gmail.com>
Cc: pablo@netfilter.org, phil@nwl.cc,
netfilter-devel@vger.kernel.org, coreteam@netfilter.org,
netdev@vger.kernel.org, stable@vger.kernel.org
Subject: Re: [PATCH v2 net] netfilter: conntrack: reject nested ctnetlink master chains
Date: Fri, 2 Oct 2026 19:35:17 +0200 [thread overview]
Message-ID: <ar_j7KcFDHntcF39@strlen.de> (raw)
In-Reply-To: <20261002165601.1754467-1-4ncienth@gmail.com>
Daehyeon Ko <4ncienth@gmail.com> wrote:
> Conntracks created through ctnetlink can reference another conntrack as
> their master. Userspace can repeat this to build an unbounded chain whose
> recursive destruction exhausts the kernel stack.
>
> Stop the repeatable userspace paths. Reject a direct master that already
> has a master, and reject NFQUEUE-attached expectations for such conntracks.
> Keep regular ctnetlink and kernel helper expectations unchanged.
>
> Fixes: 5faa1f4cb5a1 ("[NETFILTER]: nf_conntrack_netlink: add support to related connections")
> Cc: stable@vger.kernel.org
> Suggested-by: Florian Westphal <fw@strlen.de>
> Suggested-by: Pablo Neira Ayuso <pablo@netfilter.org>
> Assisted-by: LLM
> Signed-off-by: Daehyeon Ko <4ncienth@gmail.com>
LGTM. FWIW I think we should also apply the other patch to
destroy iteratively instead of recursing.
Reviewed-by: Florian Westphal <fw@strlen.de>
next prev parent reply other threads:[~2026-10-02 17:35 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-10-01 18:02 [PATCH net] netfilter: conntrack: avoid recursive master destruction Daehyeon Ko
2026-10-01 19:19 ` Florian Westphal
2026-10-02 5:39 ` Daehyeon Ko
2026-10-02 9:56 ` Pablo Neira Ayuso
2026-10-02 9:55 ` Pablo Neira Ayuso
2026-10-02 9:55 ` Pablo Neira Ayuso
2026-10-02 16:56 ` [PATCH v2 net] netfilter: conntrack: reject nested ctnetlink master chains Daehyeon Ko
2026-10-02 16:58 ` netdev-bot+sinfo
2026-10-02 17:35 ` Florian Westphal [this message]
2026-10-06 7:57 ` netdev-bot+sashiko
2026-10-07 1:33 ` Daehyeon Ko
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