linux-kernel - Re: [PATCH] tty_port: Fix refcounting leak in tty_port_tty

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Message-ID: <51F0C525.8080506@suse.cz>
Date:	Thu, 25 Jul 2013 08:26:45 +0200
From:	Jiri Slaby <jslaby@...e.cz>
To:	Gianluca Anzolin <gianluca@...tospazio.it>,
	gregkh@...uxfoundation.org
CC:	gustavo@...ovan.org, peter@...leysoftware.com,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] tty_port: Fix refcounting leak in tty_port_tty_hangup()

On 07/25/2013 07:26 AM, Gianluca Anzolin wrote:
> The function tty_port_tty_hangup() could leak a reference to the tty_struct:
> 
>         struct tty_struct *tty = tty_port_tty_get(port);
> 
>         if (tty && (!check_clocal || !C_CLOCAL(tty))) {
>                 tty_hangup(tty);
>                 tty_kref_put(tty);
>         }
> 
> If tty != NULL and the second condition is false we never call tty_kref_put and
> the reference is leaked.
> 
> Fix by always calling tty_kref_put() which accepts a NULL argument.
> 
> The patch fixes a regression introduced by commit aa27a094.
> 
> Acked-by: Gustavo Padovan <gustavo.padovan@...labora.co.uk>
> Signed-off-by: Gianluca Anzolin <gianluca@...tospazio.it>

Acked-by: Jiri Slaby <jslaby@...e.cz>

Thanks for the fix.

> ---
>  drivers/tty/tty_port.c | 5 ++---
>  1 file changed, 2 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/tty/tty_port.c b/drivers/tty/tty_port.c
> index 121aeb9..f597e88 100644
> --- a/drivers/tty/tty_port.c
> +++ b/drivers/tty/tty_port.c
> @@ -256,10 +256,9 @@ void tty_port_tty_hangup(struct tty_port *port, bool check_clocal)
>  {
>  	struct tty_struct *tty = tty_port_tty_get(port);
>  
> -	if (tty && (!check_clocal || !C_CLOCAL(tty))) {
> +	if (tty && (!check_clocal || !C_CLOCAL(tty)))
>  		tty_hangup(tty);
> -		tty_kref_put(tty);
> -	}
> +	tty_kref_put(tty);
>  }
>  EXPORT_SYMBOL_GPL(tty_port_tty_hangup);
>  
> 


-- 
js
suse labs
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