From: Florian Westphal <fw@strlen.de>
To: Bui Viet Dung <dungvn2345@gmail.com>
Cc: Pablo Neira Ayuso <pablo@netfilter.org>,
Phil Sutter <phil@nwl.cc>,
netfilter-devel@vger.kernel.org, coreteam@netfilter.org,
linux-kernel@vger.kernel.org, stable@vger.kernel.org
Subject: Re: [PATCH] netfilter: nft_set_pipapo: skip transaction elements during GC
Date: Thu, 8 Oct 2026 11:05:05 +0200 [thread overview]
Message-ID: <asdcwQRmKVA6rVyZ@strlen.de> (raw)
In-Reply-To: <20261007182057.332512-1-dungvn2345@gmail.com>
Bui Viet Dung <dungvn2345@gmail.com> wrote:
> Since nft_set_commit_update() runs set commit callbacks before processing
> NEWSETELEM transactions, pipapo_gc_scan() can observe elements added by
> the transaction being committed.
>
> The scan evaluates elements in priv->clone without checking the element's
> transaction state. Expired elements are deactivated, dropped from
> priv->clone, and queued for GC reclaim via pipapo_gc_queue().
>
> When the transaction loop in nf_tables_commit() subsequently processes
> NFT_MSG_NEWSETELEM, it calls nft_setelem_activate() on an element pointer
> that has already been handed off to GC reclaim, causing a
> slab-use-after-free.
Can you send a reproducer? I don't understand how we can add
already-expired elements, it should not be permitted?
next prev parent reply other threads:[~2026-10-08 9:05 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-10-07 18:20 [PATCH] netfilter: nft_set_pipapo: skip transaction elements during GC Bui Viet Dung
2026-10-07 19:45 ` Pablo Neira Ayuso
2026-10-08 9:05 ` Florian Westphal [this message]
2026-10-08 11:18 ` Bui Viet Dung
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