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Date:   Sun, 10 Apr 2022 17:41:44 +0200
From:   Florian Westphal <fw@strlen.de>
To:     Mark Mielke <mark.mielke@gmail.com>
Cc:     netdev@vger.kernel.org, dev@openvswitch.org,
        Pravin B Shelar <pshelar@ovn.org>,
        "David S. Miller" <davem@davemloft.net>,
        Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>,
        Pablo Neira Ayuso <pablo@netfilter.org>,
        stable@vger.kernel.org
Subject: Re: [PATCH] openvswitch: Ensure nf_ct_put is not called with null
 pointer
Message-ID: <YlL6uN9WDPtFri0p@strlen.de>
References: <20220409094036.20051-1-mark.mielke@gmail.com>
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Mark Mielke <mark.mielke@gmail.com> wrote:
> A recent commit replaced calls to nf_conntrack_put() with calls
> to nf_ct_put(). nf_conntrack_put() permitted the caller to pass
> null without side effects, while nf_ct_put() performs WARN_ON()
> and proceeds to try and de-reference the pointer. ovs-vswitchd
> triggers the warning on startup:
> 
> [   22.178881] WARNING: CPU: 69 PID: 2157 at include/net/netfilter/nf_conntrack.h:176 __ovs_ct_lookup+0x4e2/0x6a0 [openvswitch]
> ...
> [   22.213573] Call Trace:
> [   22.214318]  <TASK>
> [   22.215064]  ovs_ct_execute+0x49c/0x7f0 [openvswitch]
> ...
> Cc: stable@vger.kernel.org
> Fixes: 408bdcfce8df ("net: prefer nf_ct_put instead of nf_conntrack_put")

Actually, no.  As Pablo Neira just pointed out to me Upstream kernel is fine.
The preceeding commit made nf_ct_out() a noop when ct is NULL.