linux-kernel - [PATCH] can: j1939: undo increment when j1939_local_ecu

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Message-ID: <e7f80046-4ff7-4ce2-8ad8-7c3c678a42c9@I-love.SAKURA.ne.jp>
Date: Sun, 24 Aug 2025 19:27:40 +0900
From: Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>
To: Robin van der Gracht <robin@...tonic.nl>,
        Oleksij Rempel <o.rempel@...gutronix.de>, kernel@...gutronix.de,
        Oliver Hartkopp <socketcan@...tkopp.net>,
        Marc Kleine-Budde <mkl@...gutronix.de>,
        Maxime Jayat <maxime.jayat@...ile-devices.fr>,
        Elenita Hinds <ecathinds@...il.com>,
        Bastian Stender <bst@...gutronix.de>, linux-can@...r.kernel.org,
        LKML <linux-kernel@...r.kernel.org>
Subject: [PATCH] can: j1939: undo increment when j1939_local_ecu_get() fails

Since j1939_sk_bind() and j1939_sk_release() call j1939_local_ecu_put()
when J1939_SOCK_BOUND was already set, but the error handling path for
j1939_sk_bind() will not set J1939_SOCK_BOUND when j1939_local_ecu_get()
fails, j1939_local_ecu_get() needs to undo priv->ents[sa].nusers++ when
j1939_local_ecu_get() returns an error.

Fixes: 9d71dd0c7009 ("can: add support of SAE J1939 protocol")
Signed-off-by: Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>
---
 net/can/j1939/bus.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/net/can/j1939/bus.c b/net/can/j1939/bus.c
index 39844f14eed8..797719cb227e 100644
--- a/net/can/j1939/bus.c
+++ b/net/can/j1939/bus.c
@@ -290,8 +290,11 @@ int j1939_local_ecu_get(struct j1939_priv *priv, name_t name, u8 sa)
 	if (!ecu)
 		ecu = j1939_ecu_create_locked(priv, name);
 	err = PTR_ERR_OR_ZERO(ecu);
-	if (err)
+	if (err) {
+		if (j1939_address_is_unicast(sa))
+			priv->ents[sa].nusers--;
 		goto done;
+	}
 
 	ecu->nusers++;
 	/* TODO: do we care if ecu->addr != sa? */
-- 
2.51.0