[PATCH 5.4 25/81] can: j1939: j1939_local_ecu_get(): undo increment when j1939_local_ecu_get() fails

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

5.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>

[ Upstream commit 06e02da29f6f1a45fc07bd60c7eaf172dc21e334 ]

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>
Link: https://patch.msgid.link/e7f80046-4ff7-4ce2-8ad8-7c3c678a42c9@I-love.SAKURA.ne.jp
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 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 4866879016021..e0b966c2517cf 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