Re: [PATCH v2 2/2] mtd: nand: atmel_nand: fix a possible NULL dereference

[Josh Wu]

Hi, Corentin

On 11/24/2015 9:12 PM, LABBE Corentin wrote:
> On Fri, Nov 20, 2015 at 04:33:14PM +0800, Josh Wu wrote:
> > Hi, Corentin
> >
> > Thanks for the patch. It looks fine to me, just one nitpick in below:
> >
> > On 11/20/2015 3:45 PM, LABBE Corentin wrote:
> > > of_match_device could return NULL, and so cause a NULL pointer
> > > dereference later.
> > >
> > > Signed-off-by: LABBE Corentin <clabbe.montjoie@xxxxxxxxx>
> > > ---
> > >    drivers/mtd/nand/atmel_nand.c | 5 +++--
> > >    1 file changed, 3 insertions(+), 2 deletions(-)
> > >
> > > diff --git a/drivers/mtd/nand/atmel_nand.c b/drivers/mtd/nand/atmel_nand.c
> > > index 475c938..7902967 100644
> > > --- a/drivers/mtd/nand/atmel_nand.c
> > > +++ b/drivers/mtd/nand/atmel_nand.c
> > > @@ -1496,8 +1496,9 @@ static int atmel_of_init_port(struct atmel_nand_host *host,
> > >    	struct atmel_nand_data *board = &host->board;
> > >    	enum of_gpio_flags flags = 0;
> > >    
> > > -	host->caps = (struct atmel_nand_caps *)
> > > -		of_match_device(atmel_nand_dt_ids, host->dev)->data;
> > > +	host->caps = of_device_get_match_data(host->dev);
> > > +	if (!host->caps)
> > > +		return 1;
> > it's better to use -EINVAL here.
> Hello
>
> I do that Uwe Kleine-König said to me to do in others thread:
> https://lkml.org/lkml/2015/11/12/70 and https://lkml.org/lkml/2015/11/16/211

Thank you for the information.
I checked the imx serial driver(drivers/tty/serial/imx.c) in 
serial_imx_probe():

    ...
    ret = serial_imx_probe_dt(sport, pdev);
    if (ret > 0)     --->  So here is why you need to return 1 in 
serial_imx_probe_dt().
        serial_imx_probe_pdata(sport, pdev);
    else if (ret < 0)
        return ret;

There has a branch to check whether ret is > 0 or < 0. So that's why you 
need to return 1 in imx serial driver.

But in atmel_nand driver, we don't have such code for that. The 
atmel_of_init_port() is only used for dt probe. So if dt is not matched, 
just return an error.

> Regards
Best Regards,
Josh Wu
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