Re: [PATCH -next] pinctrl: nsp: fix potential NULL dereference in nsp_pinmux_probe()

Sudeep Holla
2018-07-11T17:01:07Z

On 11/07/18 17:48, Ray Jui wrote:
>
>
> On 7/11/2018 5:34 AM, Wei Yongjun wrote:
>> platform_get_resource() may fail and return NULL, so we should
>> better check it's return value to avoid a NULL pointer dereference
>> a bit later in the code.
>>
>> This is detected by Coccinelle semantic patch.
>>
>> @@
>> expression pdev, res, n, t, e, e1, e2;
>> @@
>>
>> res = platform_get_resource(pdev, t, n);
>> + if (!res)
>> +   return -EINVAL;
>> ... when != res = NULL
>> e = devm_ioremap_nocache(e1, res->start, e2);
>>
>> Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
>> ---
>
> Reviewed-by: Ray Jui <ray.jui@broadcom.com>
>
> Change looks good to me, although the check could have been avoided if
> 'devm_ioremap_resource' is used on the next line instead of
> 'devm_ioremap_nocache', where validation of resource pointer is done.
>
> But there's probably a reason why 'devm_ioremap_nocache' was used in
> this code here.
>

I am not sure about that. Both ARM and ARM64 has same definition as
ioremp. However, arch/arm/include/asm/io.h do mention:
"ioremap_nocache() is the same as ioremap() as there are too many device

drivers using this for device registers, and documentation which tells

people to use it for such for this to be any different."

You could technically use devm_ioremap_resource if you want.

--
Regards,
Sudeep