From nobody Sun Feb 8 22:21:33 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id B6B2CC6FD1C for ; Fri, 24 Mar 2023 13:02:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231704AbjCXNCB (ORCPT ); Fri, 24 Mar 2023 09:02:01 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46640 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231308AbjCXNB7 (ORCPT ); Fri, 24 Mar 2023 09:01:59 -0400 Received: from metis.ext.pengutronix.de (metis.ext.pengutronix.de [IPv6:2001:67c:670:201:290:27ff:fe1d:cc33]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D002C1F930 for ; Fri, 24 Mar 2023 06:01:58 -0700 (PDT) Received: from drehscheibe.grey.stw.pengutronix.de ([2a0a:edc0:0:c01:1d::a2]) by metis.ext.pengutronix.de with esmtps (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1pfh3H-0001HZ-53; Fri, 24 Mar 2023 14:01:51 +0100 Received: from [2a0a:edc0:0:1101:1d::ac] (helo=dude04.red.stw.pengutronix.de) by drehscheibe.grey.stw.pengutronix.de with esmtp (Exim 4.94.2) (envelope-from ) id 1pfh39-006O5F-EK; Fri, 24 Mar 2023 14:01:43 +0100 Received: from ore by dude04.red.stw.pengutronix.de with local (Exim 4.94.2) (envelope-from ) id 1pfh38-008wqg-My; Fri, 24 Mar 2023 14:01:42 +0100 From: Oleksij Rempel To: Robin van der Gracht , Oliver Hartkopp , Marc Kleine-Budde Cc: Oleksij Rempel , syzbot+ee1cd780f69483a8616b@syzkaller.appspotmail.com, Hillf Danton , kernel@pengutronix.de, linux-can@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v1] can: j1939: prevent deadlock by moving j1939_sk_errqueue() Date: Fri, 24 Mar 2023 14:01:41 +0100 Message-Id: <20230324130141.2132787-1-o.rempel@pengutronix.de> X-Mailer: git-send-email 2.30.2 MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-SA-Exim-Connect-IP: 2a0a:edc0:0:c01:1d::a2 X-SA-Exim-Mail-From: ore@pengutronix.de X-SA-Exim-Scanned: No (on metis.ext.pengutronix.de); SAEximRunCond expanded to false X-PTX-Original-Recipient: linux-kernel@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" 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 Signed-off-by: Hillf Danton Signed-off-by: Oleksij Rempel --- 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_sessi= on *session, =20 if (session->sk) j1939_sk_send_loop_abort(session->sk, session->err); - else - j1939_sk_errqueue(session, J1939_ERRQUEUE_RX_ABORT); } =20 static void j1939_session_cancel(struct j1939_session *session, @@ -1140,6 +1138,9 @@ static void j1939_session_cancel(struct j1939_session= *session, } =20 j1939_session_list_unlock(session->priv); + + if (!session->sk) + j1939_sk_errqueue(session, J1939_ERRQUEUE_RX_ABORT); } =20 static enum hrtimer_restart j1939_tp_txtimer(struct hrtimer *hrtimer) @@ -1253,6 +1254,9 @@ static enum hrtimer_restart j1939_tp_rxtimer(struct h= rtimer *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); } =20 j1939_session_put(session); --=20 2.30.2