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SubjectRe: [PATCH v2 2/2] mtd: nand: atmel_nand: fix a possible NULL dereference
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Hi, Corentin

On 11/24/2015 9:12 PM, LABBE Corentin wrote:
> On Fri, Nov 20, 2015 at 04:33:14PM +0800, Josh Wu wrote:
>> Hi, Corentin
>>
>> Thanks for the patch. It looks fine to me, just one nitpick in below:
>>
>> On 11/20/2015 3:45 PM, LABBE Corentin wrote:
>>> of_match_device could return NULL, and so cause a NULL pointer
>>> dereference later.
>>>
>>> Signed-off-by: LABBE Corentin <clabbe.montjoie@gmail.com>
>>> ---
>>> drivers/mtd/nand/atmel_nand.c | 5 +++--
>>> 1 file changed, 3 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/drivers/mtd/nand/atmel_nand.c b/drivers/mtd/nand/atmel_nand.c
>>> index 475c938..7902967 100644
>>> --- a/drivers/mtd/nand/atmel_nand.c
>>> +++ b/drivers/mtd/nand/atmel_nand.c
>>> @@ -1496,8 +1496,9 @@ static int atmel_of_init_port(struct atmel_nand_host *host,
>>> struct atmel_nand_data *board = &host->board;
>>> enum of_gpio_flags flags = 0;
>>>
>>> - host->caps = (struct atmel_nand_caps *)
>>> - of_match_device(atmel_nand_dt_ids, host->dev)->data;
>>> + host->caps = of_device_get_match_data(host->dev);
>>> + if (!host->caps)
>>> + return 1;
>> it's better to use -EINVAL here.
>>
> Hello
>
> I do that Uwe Kleine-König said to me to do in others thread:
> https://lkml.org/lkml/2015/11/12/70 and https://lkml.org/lkml/2015/11/16/211

Thank you for the information.
I checked the imx serial driver(drivers/tty/serial/imx.c) in
serial_imx_probe():

...
ret = serial_imx_probe_dt(sport, pdev);
if (ret > 0) ---> So here is why you need to return 1 in
serial_imx_probe_dt().
serial_imx_probe_pdata(sport, pdev);
else if (ret < 0)
return ret;

There has a branch to check whether ret is > 0 or < 0. So that's why you
need to return 1 in imx serial driver.

But in atmel_nand driver, we don't have such code for that. The
atmel_of_init_port() is only used for dt probe. So if dt is not matched,
just return an error.

>
> Regards
>
Best Regards,
Josh Wu


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