From: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> mainline inclusion from mainline-v6.18-rc2 commit 93a27b5891b8194a8c083c9a80d2141d4bf47ba8 category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/ID0R57 CVE: CVE-2025-39925 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i... -------------------------------- Currently NETDEV_UNREGISTER event handler is not calling j1939_cancel_active_session() and j1939_sk_queue_drop_all(). This will result in these calls being skipped when j1939_sk_release() is called. And I guess that the reason syzbot is still reporting unregister_netdevice: waiting for vcan0 to become free. Usage count = 2 is caused by lack of these calls. Calling j1939_cancel_active_session(priv, sk) from j1939_sk_release() can be covered by calling j1939_cancel_active_session(priv, NULL) from j1939_netdev_notify(). Calling j1939_sk_queue_drop_all() from j1939_sk_release() can be covered by calling j1939_sk_netdev_event_netdown() from j1939_netdev_notify(). Therefore, we can reuse j1939_cancel_active_session(priv, NULL) and j1939_sk_netdev_event_netdown(priv) for NETDEV_UNREGISTER event handler. Fixes: 7fcbe5b2c6a4 ("can: j1939: implement NETDEV_UNREGISTER notification handler") Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Tested-by: Oleksij Rempel <o.rempel@pengutronix.de> Acked-by: Oleksij Rempel <o.rempel@pengutronix.de> Link: https://patch.msgid.link/3ad3c7f8-5a74-4b07-a193-cb0725823558@I-love.SAKURA.... Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de> Signed-off-by: Zhang Changzhong <zhangchangzhong@huawei.com> --- net/can/j1939/main.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/net/can/j1939/main.c b/net/can/j1939/main.c index 3706a872e..a93af55 100644 --- a/net/can/j1939/main.c +++ b/net/can/j1939/main.c @@ -378,6 +378,8 @@ static int j1939_netdev_notify(struct notifier_block *nb, j1939_ecu_unmap_all(priv); break; case NETDEV_UNREGISTER: + j1939_cancel_active_session(priv, NULL); + j1939_sk_netdev_event_netdown(priv); j1939_sk_netdev_event_unregister(priv); break; } -- 2.9.5