Re: [PATCH] input: tegra-kbc: add NULL check on of_match_device() return value

[Thierry Reding <thierry.reding@gmail.com>]

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On Fri, Jul 07, 2017 at 08:42:32AM +0100, Jon Hunter wrote:
> 
> On 07/07/17 07:27, 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@embeddedor.com>
> > ---
> >  drivers/input/keyboard/tegra-kbc.c | 4 ++++
> >  1 file changed, 4 insertions(+)
> > 
> > diff --git a/drivers/input/keyboard/tegra-kbc.c b/drivers/input/keyboard/tegra-kbc.c
> > index 0c07e10..742c5ac 100644
> > --- a/drivers/input/keyboard/tegra-kbc.c
> > +++ b/drivers/input/keyboard/tegra-kbc.c
> > @@ -617,6 +617,10 @@ static int tegra_kbc_probe(struct platform_device *pdev)
> >  	const struct of_device_id *match;
> >  
> >  	match = of_match_device(tegra_kbc_of_match, &pdev->dev);
> > +	if (!match) {
> > +		dev_err(&pdev->dev, "failed to match device\n");
> > +		return -ENODEV;
> > +	}
> 
> Given that Tegra always uses device-tree, I believe that this cannot
> happen and so this additional check is not needed.

I think you can make it happen if you manually create the platform
device with a name matching that of the driver. But you really shouldn't
be doing that, so might as well let it crash and burn so that people
realize their mistake early.

Errors are easily overlooked, crashes are not.

Thierry

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