Re: [PATCH] Mtd: nand - Fix possible NULL derefrence.

[Boris Brezillon <boris.brezillon@free-electrons.com>]

On Fri, 27 Jan 2017 13:24:18 +0100
Marek Vasut <marek.vasut@gmail.com> wrote:

> On 01/27/2017 12:29 PM, Shailendra Verma wrote:
> > of_match_device could return NULL, and so can cause a NULL
> > pointer dereference later.
> > 

That's a purely hypothetical bug since the core already matched
against one of the compatible in the of_match table to decide to attach
the device to this driver. Having of_match_device() return NULL here
means something went seriously wrong (memory corruption ?).

This being said, I'm not strongly opposed to this patch. Just a minor
comment below.

Thanks,

Boris

> > Signed-off-by: Shailendra Verma <shailendra.v@samsung.com>  
> 
> Nice find, but can you split this into two patches ? And the prefix is
> 'mtd' without capital letter.
> 
> Thanks
> 
> > ---
> >  drivers/mtd/nand/mxc_nand.c  |    4 ++++
> >  drivers/mtd/nand/vf610_nfc.c |    4 ++++
> >  2 files changed, 8 insertions(+)
> > 
> > diff --git a/drivers/mtd/nand/mxc_nand.c b/drivers/mtd/nand/mxc_nand.c
> > index d7f724b..ca1b8ad 100644
> > --- a/drivers/mtd/nand/mxc_nand.c
> > +++ b/drivers/mtd/nand/mxc_nand.c
> > @@ -1596,6 +1596,10 @@ static int __init mxcnd_probe_dt(struct mxc_nand_host *host)
> >  	if (!np)
> >  		return 1;
> >  
> > +	if (!of_id) {
> > +		dev_err(host->dev, "Error: No device match found\n");
> > +		return -ENODEV;
> > +	}

Add an empty line here.

> >  	host->devtype_data = of_id->data;
> >  
> >  	return 0;
> > diff --git a/drivers/mtd/nand/vf610_nfc.c b/drivers/mtd/nand/vf610_nfc.c
> > index 3ad514c..0e09c11 100644
> > --- a/drivers/mtd/nand/vf610_nfc.c
> > +++ b/drivers/mtd/nand/vf610_nfc.c
> > @@ -674,6 +674,10 @@ static int vf610_nfc_probe(struct platform_device *pdev)
> >  	}
> >  
> >  	of_id = of_match_device(vf610_nfc_dt_ids, &pdev->dev);
> > +	if (!of_id) {
> > +		dev_err(&pdev->dev, "Error: No device match found\n");
> > +		return -ENODEV;
> > +	}

Ditto.

> >  	nfc->variant = (enum vf610_nfc_variant)of_id->data;
> >  
> >  	for_each_available_child_of_node(nfc->dev->of_node, child) {
> >   
> 
>