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Date: Tue, 3 Feb 2026 14:54:58 +0100
From: Florian Westphal <fw@strlen.de>
To: anders.grahn@gmail.com
Cc: Pablo Neira Ayuso <pablo@netfilter.org>, Phil Sutter <phil@nwl.cc>,
	"David S. Miller" <davem@davemloft.net>,
	Eric Dumazet <edumazet@google.com>,
	Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
	Simon Horman <horms@kernel.org>,
	Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
	linux-kernel@vger.kernel.org, netfilter-devel@vger.kernel.org,
	coreteam@netfilter.org, netdev@vger.kernel.org
Subject: Re: [PATCH v3] netfilter: nft_counter: Fix reset of counters on
 32bit archs
Message-ID: <aYH-Mr0Hy7EfivBt@strlen.de>
References: <20260203134831.1205444-1-anders.grahn@gmail.com>
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In-Reply-To: <20260203134831.1205444-1-anders.grahn@gmail.com>

anders.grahn@gmail.com <anders.grahn@gmail.com> wrote:
> From: Anders Grahn <anders.grahn@gmail.com>
> 
> nft_counter_reset() calls u64_stats_add() with a negative value to reset
> the counter. This will work on 64bit archs, hence the negative value
> added will wrap as a 64bit value which then can wrap the stat counter as
> well.
> 
> On 32bit archs, the added negative value will wrap as a 32bit value and
> _not_ wrapping the stat counter properly. In most cases, this would just
> lead to a very large 32bit value being added to the stat counter.
> 
> Fix by introducing u64_stats_sub().

Thanks Anders.

I will apply this in the next days unless there is a NACK from
netdev maintainers.