linux-kernel - Re: [PATCH 4/4] tty: n_gsm: fix missing corner cases in gsmld

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Date:   Thu, 7 Jul 2022 09:34:11 +0200
From:   Jiri Slaby <jirislaby@...nel.org>
To:     "Starke, Daniel" <daniel.starke@...mens.com>,
        "linux-serial@...r.kernel.org" <linux-serial@...r.kernel.org>,
        "gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>
Cc:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 4/4] tty: n_gsm: fix missing corner cases in gsmld_poll()

On 07. 07. 22, 9:00, Starke, Daniel wrote:
>>> @@ -3051,14 +3051,20 @@ static __poll_t gsmld_poll(struct tty_struct *tty, struct file *file,
>>>    	__poll_t mask = 0;
>>>    	struct gsm_mux *gsm = tty->disc_data;
>>>    
>>> +	if (!gsm)
>>> +		return EPOLLHUP;
>>
>> Hmm, how can this happen? It's a tty bug if it calls ld ops after NULLing
>> disc_data.
> 
> I can remove this check if it is redundant. Should I?

Sure as it makes little sense anyway. Even if gsm was non-NULL here, the 
backing disc_data would be freed on the accesses further.

thanks,
-- 
js
suse labs