From: "Jason A. Donenfeld" <Jason@zx2c4.com>
To: Nguyen Ngoc Thang <ngocthang2710.1999@gmail.com>
Cc: "David S . Miller" <davem@davemloft.net>,
Eric Dumazet <edumazet@google.com>,
Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
Andrew Lunn <andrew+netdev@lunn.ch>,
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
Date: Tue, 10 Nov 2026 17:20:28 +0100 [thread overview]
Message-ID: <avNETK_9e7sr-JSB@zx2c4.com> (raw)
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!
prev parent reply other threads:[~2026-11-10 16:20 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-10-11 10:23 Nguyen Ngoc Thang
2026-11-10 16:20 ` Jason A. Donenfeld [this message]
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