[PATCH] pinctrl: fix Null pointer dereference

[Drew Fustini]

On Thu, Oct 03, 2024 at 10:33:07AM +0800, clingfei wrote:
> pinmux_generic_get_function may returns NULL, and its retval is
> dereferenced without check, which will cause a null pointer dereference.
> 
> Signed-off-by: clingfei <clf700383 at gmail.com>
> ---
>  drivers/pinctrl/pinctrl-th1520.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/pinctrl/pinctrl-th1520.c b/drivers/pinctrl/pinctrl-th1520.c
> index 1bb78b212fd5..9331f4462480 100644
> --- a/drivers/pinctrl/pinctrl-th1520.c
> +++ b/drivers/pinctrl/pinctrl-th1520.c
> @@ -798,6 +798,8 @@ static int th1520_pinmux_set_mux(struct pinctrl_dev *pctldev,
>  	struct th1520_pinctrl *thp = pinctrl_dev_get_drvdata(pctldev);
>  	const struct function_desc *func = pinmux_generic_get_function(pctldev, fsel);
>  
> +	if (!func)
> +		return -EINVAL;
>  	return th1520_pinmux_set(thp, thp->desc.pins[gsel].number,
>  				 (uintptr_t)thp->desc.pins[gsel].drv_data & TH1520_PAD_MUXDATA,
>  				 (uintptr_t)func->data);
> -- 
> 2.34.1

Thanks for fixing the formating in the previous attempt.

As Kees Bakker noted [1], I failed to have this check in my v3 patch
series. This fix makes pinctrl-th1520 behave the same as other drivers
that call pinmux_generic_get_function() like pinctrl-single. I have
applied your patch and the driver still works as expected on my LPi4a.

Hopefully Linus can apply this fix on top of my v3 series.

Reviewed-by: Drew Fustini <dfustini at tenstorrent.com>

-Drew

[1] https://lore.kernel.org/lkml/87770518-5f63-4adf-b6ea-c7f92b58ce22@ijzerbout.nl/