Re: [PATCH v3 2/4] serial: mctrl_gpio: Add a NULL check to mctrl_gpio_to_gpiod()

[Uwe Kleine-König]

On Fri, Aug 02, 2019 at 10:04:10AM +0000, Schrempf Frieder wrote:
> From: Frieder Schrempf <frieder.schrempf@xxxxxxxxxx>
> 
> As it is allowed to use the mctrl_gpio_* functions before
> initialization (as the 8250 driver does according to 434be0ae7aa7),

Actually I was surprised some time ago that 8250 used serial_mctrl
without first initializing it and expecting it to work. I didn't look in
detail, but I wouldn't go so far to call this "allowed". The commit
itself calls it "workaround" which seems a better match.

> it seems appropriate to have a NULL check in all of the functions.
> Otherwise the mctrl_gpio_to_gpiod() function is prone to be used
> in a context that can lead to a NULL pointer dereference.
> 
> Signed-off-by: Frieder Schrempf <frieder.schrempf@xxxxxxxxxx>

Best regards
Uwe

-- 
Pengutronix e.K.                           | Uwe Kleine-König            |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |