Re: [PATCH] mtd: nand: mxc_nand: fix a possible NULL dereference

From: LABBE Corentin
Date: Thu Nov 12 2015 - 05:03:38 EST


On Thu, Nov 12, 2015 at 09:19:09AM +0100, Uwe Kleine-König wrote:
> Hello Corentin,
>
> On Thu, Nov 12, 2015 at 08:46:55AM +0100, 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/mxc_nand.c | 6 ++++--
> > 1 file changed, 4 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/mtd/nand/mxc_nand.c b/drivers/mtd/nand/mxc_nand.c
> > index 136e73a..9e42431 100644
> > --- a/drivers/mtd/nand/mxc_nand.c
> > +++ b/drivers/mtd/nand/mxc_nand.c
> > @@ -1464,8 +1464,7 @@ static int __init mxcnd_probe_dt(struct mxc_nand_host *host)
> > {
> > struct device_node *np = host->dev->of_node;
> > struct mxc_nand_platform_data *pdata = &host->pdata;
> > - const struct of_device_id *of_id =
> > - of_match_device(mxcnd_dt_ids, host->dev);
> > + const struct of_device_id *of_id;
> > int buswidth;
> >
> > if (!np)
> > @@ -1482,6 +1481,9 @@ static int __init mxcnd_probe_dt(struct mxc_nand_host *host)
> >
> > pdata->width = buswidth / 8;
> >
> > + of_id = of_match_device(mxcnd_dt_ids, host->dev);
> > + if (!of_id)
> > + return -ENODEV;
>
> You should return 1 here instead of -ENODEV. Also this check should
> better be done instead of
>
> if (!np)
> return 1;
>
> at the start of the function.

Are you sure for the "1" value ? It seems a very bad error value.
And I found plenty of case where if (!np) return -Esomething and no example of return 1

Regards

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