linux-kernel - Re: [PATCH] mtd: nand: vf610_nfc: add NULL check on of_match

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Date:   Mon, 17 Jul 2017 22:49:06 +0200
From:   Marek Vasut <marek.vasut@...il.com>
To:     Boris Brezillon <boris.brezillon@...e-electrons.com>,
        "Gustavo A. R. Silva" <garsilva@...eddedor.com>
Cc:     Stefan Agner <stefan@...er.ch>,
        Richard Weinberger <richard@....at>,
        David Woodhouse <dwmw2@...radead.org>,
        Brian Norris <computersforpeace@...il.com>,
        Cyrille Pitchen <cyrille.pitchen@...ev4u.fr>,
        linux-mtd@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] mtd: nand: vf610_nfc: add NULL check on of_match_device()
 return value

On 07/17/2017 10:46 PM, Boris Brezillon wrote:
> Le Fri, 7 Jul 2017 01:59:26 -0500,
> "Gustavo A. R. Silva" <garsilva@...eddedor.com> a écrit :
> 
>> 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@...eddedor.com>
>> ---
>>  drivers/mtd/nand/vf610_nfc.c | 5 +++++
>>  1 file changed, 5 insertions(+)
>>
>> diff --git a/drivers/mtd/nand/vf610_nfc.c b/drivers/mtd/nand/vf610_nfc.c
>> index 744ab10..ca0ab96 100644
>> --- a/drivers/mtd/nand/vf610_nfc.c
>> +++ b/drivers/mtd/nand/vf610_nfc.c
>> @@ -674,6 +674,11 @@ 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, "Failed to match device!\n");
>> +		return -ENODEV;
>> +	}
>> +
> 
> While this check is functionally correct, this case cannot happen,
> because this is DT-only driver, and without a valid match in
> vf610_nfc_dt_ids the dev wouldn't have been probed in the first place.
> 
> I'll let Stefan decide whether he wants it or not, but I see no real
> reason for this extra check. 

So how did you trigger the issue in the first place ?

-- 
Best regards,
Marek Vasut