linux-kernel - Re: [PATCH v2 2/2] tty: serial: 8250_core: Check that port->line is >=0

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Message-ID: <54D0E7C4.8070308@hurleysoftware.com>
Date:	Tue, 03 Feb 2015 10:22:44 -0500
From:	Peter Hurley <peter@...leysoftware.com>
To:	Michal Simek <michal.simek@...inx.com>
CC:	linux-kernel@...r.kernel.org, monstr@...str.eu,
	Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
	Jiri Slaby <jslaby@...e.cz>, Alan Cox <alan@...ux.intel.com>,
	Yoshihiro YUNOMAE <yoshihiro.yunomae.ez@...achi.com>,
	Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
	Ricardo Ribalda Delgado <ricardo.ribalda@...il.com>,
	Tony Lindgren <tony@...mide.com>, linux-serial@...r.kernel.org,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Ingo Molnar <mingo@...e.hu>
Subject: Re: [PATCH v2 2/2] tty: serial: 8250_core: Check that port->line
 is >=0

Hi Michal,

On 02/03/2015 05:01 AM, Michal Simek wrote:
> Add one more checking condition which was originally added by:
> "tty: serial: 8250_core: use the ->line argument as a hint in
> serial8250_find_match_or_unused()"
> (sha1: 59b3e898ddfc81a65975043b5eb44103cc29ff6e)
> 
> port->line can be setup by DT driver to -1 which needs to
> be also checked.

What driver is initializing port->line to -1?

Drivers using of_alias_get_id() and/or the platform device id
need to clamp port->line to a valid index before port
registration (or in the case of 8250-type drivers before
8250 port registration.


> Signed-off-by: Michal Simek <michal.simek@...inx.com>
> ---
> 
> Changes in v2:
> - Change commit message description
> - Do not sign patches - Greg reported problem with it
> 
> I have similar patch to 59b3e898ddfc81a65975043b5eb44103cc29ff6e
> in xilinx tree for a while and port->line can be -1.
> 
> The second part of this also should be (what other drivers do)

What 'second part of this'?

I only see one change here (and I'd rather see the 8250 core
return NULL if port->line < 0).

Regards,
Peter Hurley


> reading aliases via of_alias_get_id() in of_serial.c:of_platform_serial_probe()
> which setup port.line.
> ---
>  drivers/tty/serial/8250/8250_core.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/tty/serial/8250/8250_core.c b/drivers/tty/serial/8250/8250_core.c
> index 65e52c9109e2..aab765177763 100644
> --- a/drivers/tty/serial/8250/8250_core.c
> +++ b/drivers/tty/serial/8250/8250_core.c
> @@ -3512,7 +3512,8 @@ static struct uart_8250_port *serial8250_find_match_or_unused(struct uart_port *
>  
>  	/* try line number first if still available */
>  	i = port->line;
> -	if (i < nr_uarts && serial8250_ports[i].port.type == PORT_UNKNOWN &&
> +	if (i >= 0 && i < nr_uarts &&
> +	    serial8250_ports[i].port.type == PORT_UNKNOWN &&
>  			serial8250_ports[i].port.iobase == 0)
>  		return &serial8250_ports[i];
>  	/*
> 

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