[PATCH] can: j1939: undo increment when j1939_local_ecu_get() fails

[PATCH] can: j1939: undo increment when j1939_local_ecu_get() fails

[Tetsuo Handa]

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@I-love.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

Re: [PATCH] can: j1939: undo increment when j1939_local_ecu_get() fails

[Oleksij Rempel]

On Sun, Aug 24, 2025 at 07:27:40PM +0900, Tetsuo Handa wrote:
> 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@I-love.SAKURA.ne.jp>

Tested-by: Oleksij Rempel <o.rempel@pengutronix.de>                                                                                                             
Acked-by: Oleksij Rempel <o.rempel@pengutronix.de>

Thank you!
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Re: [PATCH] can: j1939: undo increment when j1939_local_ecu_get() fails

[Marc Kleine-Budde]

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On 24.08.2025 19:27:40, Tetsuo Handa wrote:
> 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@I-love.SAKURA.ne.jp>

Applied to linux-can.

regards,
Marc

-- 
Pengutronix e.K.                 | Marc Kleine-Budde          |
Embedded Linux                   | https://www.pengutronix.de |
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