From patchwork Thu Aug 22 00:17:05 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Pablo Neira Ayuso X-Patchwork-Id: 13772245 X-Patchwork-Delegate: kuba@kernel.org Received: from mail.netfilter.org (mail.netfilter.org [217.70.188.207]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 656B5442F; Thu, 22 Aug 2024 00:17:14 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.70.188.207 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1724285837; cv=none; b=T3f9UknZS4DKdfDF1Z2ga/VF6oVUkYqSrns/qdPHe87G+cHl4edtL1G5ppQtyv4fwbJy6tvHRykyohpsyAfU3LMxndwcnfDyo6BDB3Gg06lpWXszhduM+typWdFnEzVv7RFnECBX8svzLpPLof/7ChvN1QRpeTGAiy8P4aQWtgc= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1724285837; c=relaxed/simple; bh=NTD6YLYA7x1bgFibKVrKX+RosNGeZde4qslPUCQBcsc=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=kGzlRRySql/+B+p5SRYRFIpYg8VOcrTb3m8/+AI8CI008ko/l4nGLNJdyxWT+XRjs6EqjLKWVjCgzLzflTu+c9oFHxScHUjt3LsUXW2Mdd92mGtKSJA5fjlYz6mmMh2iMOdrZ7CuhDzXhWjXinLlAY0XbOJa6GVFVbXpe09TPjw= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=netfilter.org; spf=pass smtp.mailfrom=netfilter.org; arc=none smtp.client-ip=217.70.188.207 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=netfilter.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=netfilter.org From: Pablo Neira Ayuso To: netfilter-devel@vger.kernel.org Cc: davem@davemloft.net, netdev@vger.kernel.org, kuba@kernel.org, pabeni@redhat.com, edumazet@google.com, fw@strlen.de Subject: [PATCH net 1/3] netfilter: nft_counter: Disable BH in nft_counter_offload_stats(). Date: Thu, 22 Aug 2024 02:17:05 +0200 Message-Id: <20240822001707.2116-2-pablo@netfilter.org> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20240822001707.2116-1-pablo@netfilter.org> References: <20240822001707.2116-1-pablo@netfilter.org> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Patchwork-Delegate: kuba@kernel.org From: Sebastian Andrzej Siewior The sequence counter nft_counter_seq is a per-CPU counter. There is no lock associated with it. nft_counter_do_eval() is using the same counter and disables BH which suggest that it can be invoked from a softirq. This in turn means that nft_counter_offload_stats(), which disables only preemption, can be interrupted by nft_counter_do_eval() leading to two writer for one seqcount_t. This can lead to loosing stats or reading statistics while they are updated. Disable BH during stats update in nft_counter_offload_stats() to ensure one writer at a time. Fixes: b72920f6e4a9d ("netfilter: nftables: counter hardware offload support") Signed-off-by: Sebastian Andrzej Siewior Reviewed-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso --- net/netfilter/nft_counter.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/net/netfilter/nft_counter.c b/net/netfilter/nft_counter.c index 291ed2026367..16f40b503d37 100644 --- a/net/netfilter/nft_counter.c +++ b/net/netfilter/nft_counter.c @@ -265,7 +265,7 @@ static void nft_counter_offload_stats(struct nft_expr *expr, struct nft_counter *this_cpu; seqcount_t *myseq; - preempt_disable(); + local_bh_disable(); this_cpu = this_cpu_ptr(priv->counter); myseq = this_cpu_ptr(&nft_counter_seq); @@ -273,7 +273,7 @@ static void nft_counter_offload_stats(struct nft_expr *expr, this_cpu->packets += stats->pkts; this_cpu->bytes += stats->bytes; write_seqcount_end(myseq); - preempt_enable(); + local_bh_enable(); } void nft_counter_init_seqcount(void)