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Date:   Mon, 14 Aug 2023 00:17:30 +0200
From:   Florian Westphal <fw@strlen.de>
To:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc:     stable@vger.kernel.org, patches@lists.linux.dev,
        Florian Westphal <fw@strlen.de>,
        Pablo Neira Ayuso <pablo@netfilter.org>
Subject: Re: [PATCH 6.4 090/206] netfilter: nf_tables: dont skip expired
 elements during walk
Message-ID: <20230813221730.GA22068@breakpoint.cc>
References: <20230813211724.969019629@linuxfoundation.org>
 <20230813211727.651202695@linuxfoundation.org>
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Greg Kroah-Hartman <gregkh@linuxfoundation.org> wrote:
> From: Florian Westphal <fw@strlen.de>
> 
> commit 24138933b97b055d486e8064b4a1721702442a9b upstream.

Just FYI, this change is not correct.

> There is an asymmetry between commit/abort and preparation phase if the
> following conditions are met:

> 1. set is a verdict map ("1.2.3.4 : jump foo")
> 2. timeouts are enabled

[..]

> --- a/net/netfilter/nft_set_pipapo.c
> +++ b/net/netfilter/nft_set_pipapo.c
> @@ -566,8 +566,7 @@ next_match:
>  			goto out;
>  
>  		if (last) {
> -			if (nft_set_elem_expired(&f->mt[b].e->ext) ||
> -			    (genmask &&
> +			if ((genmask &&
>  			     !nft_set_elem_active(&f->mt[b].e->ext, genmask)))
>  				goto next_match;

This part is bonkers, it papers over the real issue and introduces
another bug while at it (insertions for key K will fail if we have
a key K that is already expired).

A patch to resolve it is queued on the mailing list and I'll make sure
it gets passed to the net tree by this wednesday.

Sorry for the inconvenience, I hope this doesn't interefere with
-stable release plans and this is leaves enough time for
the fix to make it to -stable too.