netdev - [PATCH net 2/3] can: j1939: make j1939_sk_bind() fail if device is no longer registered

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20251218123132.664533-3-mkl@pengutronix.de>
Date: Thu, 18 Dec 2025 10:27:18 +0100
From: Marc Kleine-Budde <mkl@...gutronix.de>
To: netdev@...r.kernel.org
Cc: davem@...emloft.net,
	kuba@...nel.org,
	linux-can@...r.kernel.org,
	kernel@...gutronix.de,
	Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>,
	Oleksij Rempel <o.rempel@...gutronix.de>,
	Marc Kleine-Budde <mkl@...gutronix.de>
Subject: [PATCH net 2/3] can: j1939: make j1939_sk_bind() fail if device is no longer registered

From: Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>

There is a theoretical race window in j1939_sk_netdev_event_unregister()
where two j1939_sk_bind() calls jump in between read_unlock_bh() and
lock_sock().

The assumption jsk->priv == priv can fail if the first j1939_sk_bind()
call once made jsk->priv == NULL due to failed j1939_local_ecu_get() call
and the second j1939_sk_bind() call again made jsk->priv != NULL due to
successful j1939_local_ecu_get() call.

Since the socket lock is held by both j1939_sk_netdev_event_unregister()
and j1939_sk_bind(), checking ndev->reg_state with the socket lock held can
reliably make the second j1939_sk_bind() call fail (and close this race
window).

Fixes: 7fcbe5b2c6a4 ("can: j1939: implement NETDEV_UNREGISTER notification handler")
Signed-off-by: Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>
Acked-by: Oleksij Rempel <o.rempel@...gutronix.de>
Link: https://patch.msgid.link/5732921e-247e-4957-a364-da74bd7031d7@I-love.SAKURA.ne.jp
Signed-off-by: Marc Kleine-Budde <mkl@...gutronix.de>
---
 net/can/j1939/socket.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/net/can/j1939/socket.c b/net/can/j1939/socket.c
index 6272326dd614..ff9c4fd7b433 100644
--- a/net/can/j1939/socket.c
+++ b/net/can/j1939/socket.c
@@ -482,6 +482,12 @@ static int j1939_sk_bind(struct socket *sock, struct sockaddr_unsized *uaddr, in
 			goto out_release_sock;
 		}

+		if (ndev->reg_state != NETREG_REGISTERED) {
+			dev_put(ndev);
+			ret = -ENODEV;
+			goto out_release_sock;
+		}
+
 		can_ml = can_get_ml_priv(ndev);
 		if (!can_ml) {
 			dev_put(ndev);
-- 
2.51.0