linux-kernel - Re: [V1] mtd: devices: docg3:- Handle return value of devm

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Date:   Mon, 12 Dec 2016 08:29:19 +0530
From:   arvind Yadav <arvind.yadav.cs@...il.com>
To:     Marek Vasut <marek.vasut@...il.com>, robert.jarzmik@...e.fr,
        dwmw2@...radead.org, computersforpeace@...il.com,
        boris.brezillon@...e-electrons.com, richard@....at,
        cyrille.pitchen@...el.com
Cc:     linux-mtd@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [V1] mtd: devices: docg3:- Handle return value of devm_ioremap.

Yes, We are returning -ENOMEM, ret is initialized to -ENOMEM.
As per your concern, I have added dev_err failure message.

Thanks
-Arvind

On Monday 12 December 2016 12:45 AM, Marek Vasut wrote:
> On 12/11/2016 07:01 PM, Arvind Yadav wrote:
>> Here, If devm_ioremap will fail. It will return NULL.
>> Kernel can run into a NULL-pointer dereference.
>>
>> Signed-off-by: Arvind Yadav <arvind.yadav.cs@...il.com>
>> ---
>>   drivers/mtd/devices/docg3.c | 5 ++++-
>>   1 file changed, 4 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/mtd/devices/docg3.c b/drivers/mtd/devices/docg3.c
>> index b833e6c..013b5b9 100644
>> --- a/drivers/mtd/devices/docg3.c
>> +++ b/drivers/mtd/devices/docg3.c
>> @@ -2083,9 +2083,12 @@ static int __init docg3_probe(struct platform_device *pdev)
>>   		dev_err(dev, "No I/O memory resource defined\n");
>>   		return ret;
>>   	}
>> -	base = devm_ioremap(dev, ress->start, DOC_IOSPACE_SIZE);
>>   
>>   	ret = -ENOMEM;
>> +	base = devm_ioremap(dev, ress->start, DOC_IOSPACE_SIZE);
>> +	if (!base)
>> +		return ret;
> I think return -ENOMEM right away won't hurt here. Also, dev_err()
> explaining the failure would be nice to add.
>
> Thanks!
>
>>   	cascade = devm_kzalloc(dev, sizeof(*cascade) * DOC_MAX_NBFLOORS,
>>   			       GFP_KERNEL);
>>   	if (!cascade)
>>
>