From c3c06c61890da80494bb196f75d89b791adda87f Mon Sep 17 00:00:00 2001
From: Yang Yingliang <yangyingliang@huawei.com>
Date: Thu, 27 Oct 2022 17:12:37 +0800
Subject: [PATCH] can: j1939: transport: j1939_session_skb_drop_old(): spin_unlock_irqrestore() before kfree_skb()
Git-commit: c3c06c61890da80494bb196f75d89b791adda87f
Patch-mainline: v6.1-rc3
References: git-fixes

It is not allowed to call kfree_skb() from hardware interrupt context
or with interrupts being disabled. The skb is unlinked from the queue,
so it can be freed after spin_unlock_irqrestore().

Fixes: 9d71dd0c7009 ("can: add support of SAE J1939 protocol")
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
Acked-by: Oleksij Rempel <o.rempel@pengutronix.de>
Link: https://lore.kernel.org/all/20221027091237.2290111-1-yangyingliang@huawei.com
Cc: stable@vger.kernel.org
[mkl: adjust subject]
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 net/can/j1939/transport.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/net/can/j1939/transport.c b/net/can/j1939/transport.c
index d7d86c944d76..55f29c9f9e08 100644
--- a/net/can/j1939/transport.c
+++ b/net/can/j1939/transport.c
@@ -342,10 +342,12 @@ static void j1939_session_skb_drop_old(struct j1939_session *session)
 		__skb_unlink(do_skb, &session->skb_queue);
 		/* drop ref taken in j1939_session_skb_queue() */
 		skb_unref(do_skb);
+		spin_unlock_irqrestore(&session->skb_queue.lock, flags);
 
 		kfree_skb(do_skb);
+	} else {
+		spin_unlock_irqrestore(&session->skb_queue.lock, flags);
 	}
-	spin_unlock_irqrestore(&session->skb_queue.lock, flags);
 }
 
 void j1939_session_skb_queue(struct j1939_session *session,
-- 
2.35.3