Received-SPF: pass (google.com: domain of linux-kernel+bounces-155104-linux.lists.archive=gmail.com@vger.kernel.org designates 2604:1380:4601:e00::3 as permitted sender) client-ip=2604:1380:4601:e00::3;
Message-ID: <tencent_284407955020261D1B2BD142194A87C9EB0A@qq.com>
From: linke li <lilinke99@qq.com>
To: 
Cc: xujianhao01@gmail.com,
	linke li <lilinke99@qq.com>,
	Pablo Neira Ayuso <pablo@netfilter.org>,
	Jozsef Kadlecsik <kadlec@netfilter.org>,
	Florian Westphal <fw@strlen.de>,
	"David S. Miller" <davem@davemloft.net>,
	Eric Dumazet <edumazet@google.com>,
	Jakub Kicinski <kuba@kernel.org>,
	Paolo Abeni <pabeni@redhat.com>,
	netfilter-devel@vger.kernel.org,
	coreteam@netfilter.org,
	netdev@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: [PATCH] netfilter: mark racy access on ext->gen_id
Date: Tue, 23 Apr 2024 19:50:22 +0800
Precedence: bulk
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit

In __nf_ct_ext_find(), ext->gen_id can be changed by 
nf_ct_ext_valid_post(), using WRITE_ONCE. Mark data races on ext->gen_id
as benign using READ_ONCE. 

This patch is aimed at reducing the number of benign races reported by
KCSAN in order to focus future debugging effort on harmful races.

Signed-off-by: linke li <lilinke99@qq.com>
---
 net/netfilter/nf_conntrack_extend.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/netfilter/nf_conntrack_extend.c b/net/netfilter/nf_conntrack_extend.c
index dd62cc12e775..7f1a5e5f6646 100644
--- a/net/netfilter/nf_conntrack_extend.c
+++ b/net/netfilter/nf_conntrack_extend.c
@@ -141,7 +141,7 @@ void *__nf_ct_ext_find(const struct nf_ct_ext *ext, u8 id)
 	if (!__nf_ct_ext_exist(ext, id))
 		return NULL;
 
-	if (this_id == 0 || ext->gen_id == gen_id)
+	if (this_id == 0 || READ_ONCE(ext->gen_id) == gen_id)
 		return (void *)ext + ext->offset[id];
 
 	return NULL;
-- 
2.39.3 (Apple Git-146)