linux-kernel - Re: [PATCH net 3/3] vsock: Fix transport

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Message-ID: <f96fb2fc-53ca-4e47-ab94-81c2f7b7c61a@rbox.co>
Date: Fri, 20 Jun 2025 14:57:33 +0200
From: Michal Luczaj <mhal@...x.co>
To: Stefano Garzarella <sgarzare@...hat.com>
Cc: "David S. Miller" <davem@...emloft.net>,
 Eric Dumazet <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>,
 Paolo Abeni <pabeni@...hat.com>, Simon Horman <horms@...nel.org>,
 virtualization@...ts.linux.dev, netdev@...r.kernel.org,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH net 3/3] vsock: Fix transport_* TOCTOU

On 6/20/25 10:37, Stefano Garzarella wrote:
>> -	if (!new_transport || !try_module_get(new_transport->module))
>> -		return -ENODEV;
>> +	if (!new_transport || !try_module_get(new_transport->module)) {
>> +		ret = -ENODEV;
>> +		goto unlock;
>> +	}
>> +
> 
> I'd add a comment here to explain that we can release it since we
> successfully increased the `new_transport` refcnt.

Sure, will do.

>> +	mutex_unlock(&vsock_register_mutex);
>>
>> 	if (sk->sk_type == SOCK_SEQPACKET) {
>> 		if (!new_transport->seqpacket_allow ||
>> @@ -528,6 +539,9 @@ int vsock_assign_transport(struct vsock_sock *vsk, struct vsock_sock *psk)
>> 	vsk->transport = new_transport;
>>
>> 	return 0;
>> +unlock:
> 
> I'd call it `err:` so it's clear is the error path.

Right, that makes sense.

Thanks!
Michal