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From:   Fedor Pchelkin <pchelkin@ispras.ru>
To:     Robin van der Gracht <robin@protonic.nl>,
        Oleksij Rempel <linux@rempel-privat.de>
Cc:     Fedor Pchelkin <pchelkin@ispras.ru>, kernel@pengutronix.de,
        Oliver Hartkopp <socketcan@hartkopp.net>,
        Marc Kleine-Budde <mkl@pengutronix.de>,
        "David S. Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
        Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>,
        Kurt Van Dijck <dev.kurt@vandijck-laurijssen.be>,
        Bastian Stender <bst@pengutronix.de>,
        linux-can@vger.kernel.org, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org,
        Alexey Khoroshilov <khoroshilov@ispras.ru>,
        ldv-project@linuxtesting.org
Subject: [PATCH] can: j1939: Replace WARN_ON_ONCE with pr_warn_once() in j1939_sk_queue_activate_next_locked()
Date:   Thu, 28 Jul 2022 19:34:29 +0300
Message-Id: <20220728163429.214758-1-pchelkin@ispras.ru>
In-Reply-To: <7ea40c0e-e696-3537-c2a4-a8eccf4695d0@ispras.ru>
References: 
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We should warn user-space that it is doing something wrong when trying to
activate sessions with identical parameters but WARN_ON_ONCE macro can not
be used here as it serves a different purpose.

Found by Linux Verification Center (linuxtesting.org) with Syzkaller.

Fixes: 9d71dd0c7009 ("can: add support of SAE J1939 protocol")
Signed-off-by: Fedor Pchelkin <pchelkin@ispras.ru>
Signed-off-by: Alexey Khoroshilov <khoroshilov@ispras.ru>
---
 net/can/j1939/socket.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/net/can/j1939/socket.c b/net/can/j1939/socket.c
index f5ecfdcf57b2..67e8b50b8bc1 100644
--- a/net/can/j1939/socket.c
+++ b/net/can/j1939/socket.c
@@ -178,7 +178,8 @@ static void j1939_sk_queue_activate_next_locked(struct j1939_session *session)
 	if (!first)
 		return;
 
-	if (WARN_ON_ONCE(j1939_session_activate(first))) {
+	if (j1939_session_activate(first)) {
+		pr_warn_once("can: j1939: Identical session is already activated.\n");
 		first->err = -EBUSY;
 		goto activate_next;
 	} else {
-- 
2.25.1