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Date:   Mon, 25 Apr 2022 12:53:54 +0200
From:   Florian Westphal <fw@strlen.de>
To:     Ilya Maximets <i.maximets@ovn.org>
Cc:     Florian Westphal <fw@strlen.de>,
        Mark Mielke <mark.mielke@gmail.com>, dev@openvswitch.org,
        netdev@vger.kernel.org, stable@vger.kernel.org,
        Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>,
        "David S. Miller" <davem@davemloft.net>,
        Pablo Neira Ayuso <pablo@netfilter.org>,
        Antti Antinoja <antti@fennosys.fi>
Subject: Re: [ovs-dev] [PATCH] openvswitch: Ensure nf_ct_put is not called
 with null pointer
Message-ID: <20220425105354.GC26757@breakpoint.cc>
References: <20220409094036.20051-1-mark.mielke@gmail.com>
 <YlL6uN9WDPtFri0p@strlen.de>
 <590d44a1-ca27-c171-de87-fe57fc07dff5@ovn.org>
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Ilya Maximets <i.maximets@ovn.org> wrote:
> Hi, Florian.
> 
> There is a problem on 5.15 longterm tree where the offending commit
> got backported, but the previous one was not, so it triggers an issue
> while loading the openvswitch module.
> 
> To be more clear, v5.15.35 contains the following commit:
>   408bdcfce8df ("net: prefer nf_ct_put instead of nf_conntrack_put")
> backported as commit 72dd9e61fa319bc44020c2d365275fc8f6799bff, but
> it doesn't have the previous one:
>   6ae7989c9af0 ("netfilter: conntrack: avoid useless indirection during conntrack destruction")
> that adds the NULL pointer check to the nf_ct_put().
> 
> Either 6ae7989c9af0 should be backported to 5.15 or 72dd9e61fa31
> reverted on that tree.

The commit was never meant to be backported to stable, it doesn't fix any bug.

I suspect it was done to take 'net/sched: act_ct: fix ref leak when
switching zones' without munging it.

I suggest to add stable-only patch that makes nf_ct_put(NULL)
legal, like in linux.git, but I don't know stable team preferences.