[PATCH] soc: imx: imx8m-blk-ctrl: Fix NULL pointer dereference

[Marco Felsch]

Hi Ma,

thank you for the patch.

On 24-08-08, Ma Ke wrote:
> Check bc->bus_power_dev = dev_pm_domain_attach_by_name() return value using
> IS_ERR_OR_NULL() instead of plain IS_ERR(), and fail if bc->bus_power_dev 
> is either error or NULL.
> 
> In case a power domain attached by dev_pm_domain_attach_by_name() is not
> described in DT, dev_pm_domain_attach_by_name() returns NULL, which is
> then used, which leads to NULL pointer dereference.

Argh.. there are other users of this API getting this wrong too. This
make me wonder why dev_pm_domain_attach_by_name() return NULL instead of
the error code returned by of_property_match_string().

IMHO to fix once and for all users we should fix the return code of
dev_pm_domain_attach_by_name().

Regards,
  Marco

> Found by code review.
> 
> Cc: stable at vger.kernel.org
> Fixes: 1a1da28544fd ("soc: imx: imx8m-blk-ctrl: Defer probe if 'bus' genpd is not yet ready")
> Signed-off-by: Ma Ke <make24 at iscas.ac.cn>
> ---
>  drivers/pmdomain/imx/imx8m-blk-ctrl.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/pmdomain/imx/imx8m-blk-ctrl.c b/drivers/pmdomain/imx/imx8m-blk-ctrl.c
> index ca942d7929c2..d46fb5387148 100644
> --- a/drivers/pmdomain/imx/imx8m-blk-ctrl.c
> +++ b/drivers/pmdomain/imx/imx8m-blk-ctrl.c
> @@ -212,7 +212,7 @@ static int imx8m_blk_ctrl_probe(struct platform_device *pdev)
>  		return -ENOMEM;
>  
>  	bc->bus_power_dev = dev_pm_domain_attach_by_name(dev, "bus");
> -	if (IS_ERR(bc->bus_power_dev)) {
> +	if (IS_ERR_OR_NULL(bc->bus_power_dev)) {
>  		if (PTR_ERR(bc->bus_power_dev) == -ENODEV)
>  			return dev_err_probe(dev, -EPROBE_DEFER,
>  					     "failed to attach power domain \"bus\"\n");
> -- 
> 2.25.1
> 
> 
>