From: Pablo Neira Ayuso <pablo@netfilter.org>
To: Florian Westphal <fw@strlen.de>
Cc: netfilter-devel@vger.kernel.org
Subject: Re: [PATCH nf] netfilter: fix possible bug_on with enable_hooks=1
Date: Wed, 10 May 2023 08:33:14 +0200 [thread overview]
Message-ID: <ZFs6qpQB8rfK0kPd@calendula> (raw)
In-Reply-To: <20230504125502.22512-1-fw@strlen.de>
On Thu, May 04, 2023 at 02:55:02PM +0200, Florian Westphal wrote:
> I received a bug report (no reproducer so far) where we trip over
>
> 712 rcu_read_lock();
> 713 ct_hook = rcu_dereference(nf_ct_hook);
> 714 BUG_ON(ct_hook == NULL); // here
>
> In nf_conntrack_destroy().
>
> First turn this BUG_ON into a WARN. I think it was triggered
> via enable_hooks=1 flag.
>
> When this flag is turned on, the conntrack hooks are registered
> before nf_ct_hook pointer gets assigned.
> This opens a short window where packets enter the conntrack machinery,
> can have skb->_nfct set up and a subsequent kfree_skb might occur
> before nf_ct_hook is set.
>
> Call nf_conntrack_init_end() to set nf_ct_hook before we register the
> pernet ops.
Applied to nf, thanks
prev parent reply other threads:[~2023-05-10 6:33 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-05-04 12:55 [PATCH nf] netfilter: fix possible bug_on with enable_hooks=1 Florian Westphal
2023-05-10 6:33 ` Pablo Neira Ayuso [this message]
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