Re: [PATCH] net: ethernet: mediatek: add NULL check on of_match_device() return value

[Gustavo A. R. Silva]

Hi Andrew,

Quoting Andrew Lunn <andrew@xxxxxxx>:

> On Fri, Jul 07, 2017 at 02:11:35AM -0500, Gustavo A. R. Silva wrote:
> > Check return value from call to of_match_device()
> > in order to prevent a NULL pointer dereference.
> >
> > In case of NULL print error message and return -ENODEV
> >
> > Signed-off-by: Gustavo A. R. Silva <garsilva@xxxxxxxxxxxxxx>
> > ---
> >  drivers/net/ethernet/mediatek/mtk_eth_soc.c | 5 +++++
> >  1 file changed, 5 insertions(+)
> >
> > diff --git a/drivers/net/ethernet/mediatek/mtk_eth_soc.c  
> > b/drivers/net/ethernet/mediatek/mtk_eth_soc.c
> > index adaaafc..6a77dea 100644
> > --- a/drivers/net/ethernet/mediatek/mtk_eth_soc.c
> > +++ b/drivers/net/ethernet/mediatek/mtk_eth_soc.c
> > @@ -2408,6 +2408,11 @@ static int mtk_probe(struct platform_device *pdev)
> >  	int i;
> >
> >  	match = of_match_device(of_mtk_match, &pdev->dev);
> > +	if (!match) {
> > +		dev_err(&pdev->dev, "failed to match device\n");
> > +		return -ENODEV;
> > +	}
> > +
> >  	soc = (struct mtk_soc_data *)match->data;
>
> Hi Gustavo
>
> I think you are fixing the wrong thing. The soc variable is unused. Also,
>
> const struct of_device_id of_mtk_match[] = {
>         { .compatible = "mediatek,mt2701-eth" },
>         {},
> };
>
> So match->data is NULL. This code is all pointless and should be
> removed, rather than try to avoid a NULL pointer dereference which can
> not actually happen.

You are right. Thank you for pointing it out. I'll remove that code  
and send a new patch shortly.

Thanks!
--
Gustavo A. R. Silva