netdev - Re: [PATCH net 3/4] can: raw: instantly reject disabled CAN frames

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Message-ID: <0636c732-2e71-4633-8005-dfa85e1da445@hartkopp.net>
Date: Thu, 15 Jan 2026 08:55:33 +0100
From: Oliver Hartkopp <socketcan@...tkopp.net>
To: Marc Kleine-Budde <mkl@...gutronix.de>, netdev@...r.kernel.org
Cc: davem@...emloft.net, kuba@...nel.org, linux-can@...r.kernel.org,
 kernel@...gutronix.de, Arnd Bergmann <arnd@...db.de>,
 Vincent Mailhol <mailhol@...nel.org>
Subject: Re: [PATCH net 3/4] can: raw: instantly reject disabled CAN frames

Hello Marc,

On 14.01.26 11:45, Marc Kleine-Budde wrote:
> From: Oliver Hartkopp <socketcan@...tkopp.net>

> @@ -944,6 +945,10 @@ static int raw_sendmsg(struct socket *sock, struct msghdr *msg, size_t size)
>   	if (!dev)
>   		return -ENXIO;
>   
> +	/* no sending on a CAN device in read-only mode */
> +	if (can_cap_enabled(dev, CAN_CAP_RO))
> +		return -EACCES;
> +
>   	skb = sock_alloc_send_skb(sk, size + sizeof(struct can_skb_priv),
>   				  msg->msg_flags & MSG_DONTWAIT, &err);
>   	if (!skb)

At midnight the AI review from the netdev patchwork correctly identified 
a problem with the above code:

https://netdev-ai.bots.linux.dev/ai-review.html?id=fb201338-eed0-488f-bb32-5240af254cf4

An excellent tool indeed!

This patch has to be changed to not leak a dev reference.

Can you please change it in your tree and send an updated PR?

Sorry for that extra effort :-/

Best regards,
Oliver


diff --git a/net/can/raw.c b/net/can/raw.c
index d66036da6753..12293363413c 100644
--- a/net/can/raw.c
+++ b/net/can/raw.c
@@ -944,12 +944,14 @@ static int raw_sendmsg(struct socket *sock, struct 
msghdr *msg, size_t size)
  	dev = dev_get_by_index(sock_net(sk), ifindex);
  	if (!dev)
  		return -ENXIO;

  	/* no sending on a CAN device in read-only mode */
-	if (can_cap_enabled(dev, CAN_CAP_RO))
-		return -EACCES;
+	if (can_cap_enabled(dev, CAN_CAP_RO)) {
+		err = -EACCES;
+		goto put_dev;
+	}

  	skb = sock_alloc_send_skb(sk, size + sizeof(struct can_skb_priv),
  				  msg->msg_flags & MSG_DONTWAIT, &err);
  	if (!skb)
  		goto put_dev;