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[104.131.123.232]) by smtp-relay.gmail.com with ESMTPS id af79cd13be357-9479efb239csm35618885a.10.2026.11.10.08.20.34 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 10 Nov 2026 08:20:34 -0800 (PST) X-Relaying-Domain: zx2c4.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=zx2c4.com; s=20210105; t=1794327631; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=Wn9pl2dWY0mvsidzC7ZDrdvAm0x6tULK0E6nQnzg3QE=; b=oMYGPlhN+9g4AeBDfpCGTBZvu9Avf73LXYnRU6qvPzJzuBsQ3shkH5vxk/jmMg8gWGzwbl iRS9Y/grD05nLAnzDqY6ePcGBUuSJekQMzyZ7RF8Z1y6YzzHA0AyatbgR2FGsdiWhRAshw xeD1NXhYrsxQ+z6vA0sPv74b16eUe6U= Received: by mail.zx2c4.com (OpenSMTPD) with ESMTPSA id cd041934 (TLSv1.3:TLS_AES_256_GCM_SHA384:256:NO); Tue, 10 Nov 2026 16:20:31 +0000 (UTC) Date: Tue, 10 Nov 2026 17:20:28 +0100 From: "Jason A. Donenfeld" To: Nguyen Ngoc Thang Cc: "David S . Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Andrew Lunn , wireguard@lists.zx2c4.com, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, syzbot+de9701a2cad597c14d34@syzkaller.appspotmail.com Subject: Re: [PATCH net] wireguard: mark racy persistent_keepalive_interval accesses Message-ID: References: <20261011102322.355167-1-ngocthang2710.1999@gmail.com> X-Mailing-List: netdev@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20261011102322.355167-1-ngocthang2710.1999@gmail.com> On Sun, Oct 11, 2026 at 05:23:22PM +0700, Nguyen Ngoc Thang wrote: > wg_set_device_doit() updates peer->persistent_keepalive_interval under > device_update_lock, while the RX/TX paths read it locklessly in > wg_timers_any_authenticated_packet_traversal() and in the persistent > keepalive timer. KCSAN reports the race: > > BUG: KCSAN: data-race in set_peer / wg_timers_any_authenticated_packet_traversal > > write to ... by task 3648 on cpu 1: > set_peer+0x... drivers/net/wireguard/netlink.c:457 > wg_set_device_doit+0x... > read to ... by task 3652 on cpu 0: > wg_timers_any_authenticated_packet_traversal+0x... timers.c:217 > wg_packet_consume_data_done+0x... > wg_packet_rx_poll+0x... > > The race is benign, but the reader also loads the field twice, so the > zero check and the timer expiry computation can see different values. > Load it once with READ_ONCE() and mark the writer and the other > lockless reader accordingly. Applied, thank you!