From: Oleksij Rempel o.rempel@pengutronix.de

This commit addresses a deadlock situation that can occur in certain scenarios, such as when running data TP/ETP transfer and subscribing to the error queue while receiving a net down event. The deadlock involves locks in the following order:

3 j1939_session_list_lock -> active_session_list_lock j1939_session_activate ... j1939_sk_queue_activate_next -> sk_session_queue_lock ... j1939_xtp_rx_eoma_one

2 j1939_sk_queue_drop_all -> sk_session_queue_lock ... j1939_sk_netdev_event_netdown -> j1939_socks_lock j1939_netdev_notify

1 j1939_sk_errqueue -> j1939_socks_lock __j1939_session_cancel -> active_session_list_lock j1939_tp_rxtimer

CPU0 CPU1 ---- ---- lock(&priv->active_session_list_lock); lock(&jsk->sk_session_queue_lock); lock(&priv->active_session_list_lock); lock(&priv->j1939_socks_lock);

The solution implemented in this commit is to move the j1939_sk_errqueue() call out of the active_session_list_lock context, thus preventing the deadlock situation.

Reported-by: syzbot+ee1cd780f69483a8616b@syzkaller.appspotmail.com Fixes: 5b9272e93f2e ("can: j1939: extend UAPI to notify about RX status") Co-developed-by: Hillf Danton hdanton@sina.com Signed-off-by: Hillf Danton hdanton@sina.com Signed-off-by: Oleksij Rempel o.rempel@pengutronix.de Link: https://lore.kernel.org/all/20230324130141.2132787-1-o.rempel@pengutronix.de Cc: stable@vger.kernel.org Signed-off-by: Marc Kleine-Budde mkl@pengutronix.de --- net/can/j1939/transport.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/net/can/j1939/transport.c b/net/can/j1939/transport.c index fce9b9ebf13f..fb92c3609e17 100644 --- a/net/can/j1939/transport.c +++ b/net/can/j1939/transport.c @@ -1124,8 +1124,6 @@ static void __j1939_session_cancel(struct j1939_session *session,

if (session->sk) j1939_sk_send_loop_abort(session->sk, session->err); - else - j1939_sk_errqueue(session, J1939_ERRQUEUE_RX_ABORT); }

static void j1939_session_cancel(struct j1939_session *session, @@ -1140,6 +1138,9 @@ static void j1939_session_cancel(struct j1939_session *session, }

j1939_session_list_unlock(session->priv); + + if (!session->sk) + j1939_sk_errqueue(session, J1939_ERRQUEUE_RX_ABORT); }

static enum hrtimer_restart j1939_tp_txtimer(struct hrtimer *hrtimer) @@ -1253,6 +1254,9 @@ static enum hrtimer_restart j1939_tp_rxtimer(struct hrtimer *hrtimer) __j1939_session_cancel(session, J1939_XTP_ABORT_TIMEOUT); } j1939_session_list_unlock(session->priv); + + if (!session->sk) + j1939_sk_errqueue(session, J1939_ERRQUEUE_RX_ABORT); }

j1939_session_put(session);

base-commit: 45977e58ce65ed0459edc9a0466d9dfea09463f5