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

Schrempf Frieder
2019-08-05T09:01:43Z

On 02.08.19 14:12, Uwe Kleine-König wrote:
> On Fri, Aug 02, 2019 at 10:04:10AM +0000, Schrempf Frieder wrote:
>> From: Frieder Schrempf <frieder.schrempf@kontron.de>
>>
>> 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.

Ok, but if this is considered to be a workaround and as the 8250 driver
does not use mctrl_gpio_to_gpiod(), we should maybe just drop this patch
instead of encouraging others to use mctrl_gpio before initialization.

I'm really not sure what's best, so depending on what you will propose,
I'll send a new version of this patch with adjusted commit message or not.

By the way, Uwe and Fabio: Thanks for your reviews!

>
>> 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@kontron.de>
>
> Best regards
> Uwe
>