linux-kernel - Re: [PATCH] mtd: rawnand: vf610: Fix to check for NULL pointer dereference

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Date:   Mon, 1 Apr 2019 17:30:56 +0200
From:   Boris Brezillon <boris.brezillon@...labora.com>
To:     Miquel Raynal <miquel.raynal@...tlin.com>
Cc:     Aditya Pakki <pakki001@....edu>, kjlu@....edu,
        Stefan Agner <stefan@...er.ch>,
        Boris Brezillon <bbrezillon@...nel.org>,
        Richard Weinberger <richard@....at>,
        David Woodhouse <dwmw2@...radead.org>,
        Brian Norris <computersforpeace@...il.com>,
        Marek Vasut <marek.vasut@...il.com>,
        linux-mtd@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] mtd: rawnand: vf610: Fix to check for NULL pointer
 dereference

On Mon, 1 Apr 2019 17:26:51 +0200
Miquel Raynal <miquel.raynal@...tlin.com> wrote:

> Hi Aditya,
> 
> Aditya Pakki <pakki001@....edu> wrote on Mon, 18 Mar 2019 18:24:34
> -0500:
> 
> > of_match_device can return NULL if there is no matching device is found.
> > The patch avoids a potential NULL pointer dereference by checking for the
> > return value and passing the error upstream.
> > 
> > Signed-off-by: Aditya Pakki <pakki001@....edu>
> > ---
> >  drivers/mtd/nand/raw/vf610_nfc.c | 2 ++
> >  1 file changed, 2 insertions(+)
> > 
> > diff --git a/drivers/mtd/nand/raw/vf610_nfc.c b/drivers/mtd/nand/raw/vf610_nfc.c
> > index a662ca1970e5..946abbb275c3 100644
> > --- a/drivers/mtd/nand/raw/vf610_nfc.c
> > +++ b/drivers/mtd/nand/raw/vf610_nfc.c
> > @@ -850,6 +850,8 @@ static int vf610_nfc_probe(struct platform_device *pdev)
> >  	}
> >  
> >  	of_id = of_match_device(vf610_nfc_dt_ids, &pdev->dev);
> > +	if (!of_id)
> > +		return -ENODEV;

For the record, this can't happen unless you have serious memory
corruption issues since you reached the ->probe() function (which means
a match was found before).

> >  	nfc->variant = (enum vf610_nfc_variant)of_id->data;
> >  
> >  	for_each_available_child_of_node(nfc->dev->of_node, child) {  
> 
> 
> Applied to git://git.kernel.org/pub/scm/linux/kernel/git/mtd/linux.git
> on nand/next with the title changed to
> 
>         mtd: rawnand: vf610: Avoid a potential NULL pointer dereference
> 
> and a space after the return statement.
> 
> Thanks,
> Miquèl