Re: [PATCH v4 02/10] mei: late_bind: add late binding component driver

["Nilawar, Badal" <badal.nilawar@intel.com>]

On 01-07-2025 15:15, Greg KH wrote:
> On Tue, Jul 01, 2025 at 02:02:15PM +0530, Nilawar, Badal wrote:
>> On 28-06-2025 17:48, Greg KH wrote:
>>>> + * @payload_size: size of the payload data in bytes
>>>> + * @payload: data to be sent to the firmware
>>>> + */
>>>> +struct csc_heci_late_bind_req {
>>>> +	struct mkhi_msg_hdr header;
>>>> +	u32 type;
>>>> +	u32 flags;
>>> What is the endian of these fields?  And as this crosses the
>>> kernel/hardware boundry, shouldn't these be __u32?
>> endian of these fields is little endian, all the headers are little endian.
>> I will add comment at top.
> No, use the proper types if this is little endian.  Don't rely on a
> comment to catch things when it goes wrong.
>
>> On __u32 I doubt we need to do it as csc send copy it to internal buffer.
> If this crosses the kernel boundry, it needs to use the proper type.

Understood. I will proceed with using __le32 in this context, provided 
that Sasha agrees.

>
>>>> +{
>>>> +	struct mei_cl_device *cldev;
>>>> +	struct csc_heci_late_bind_req *req = NULL;
>>>> +	struct csc_heci_late_bind_rsp rsp;
>>>> +	size_t req_size;
>>>> +	ssize_t ret;
>>>> +
>>>> +	if (!dev || !payload || !payload_size)
>>>> +		return -EINVAL;
>>> How can any of these ever happen as you control the callers of this
>>> function?
>> I will add WARN here.
> So you will end up crashing the machine and getting a CVE assigned for
> it?
>
> Please no.  If it can't happen, then don't check for it.  If it can
> happen, great, handle it properly.  Don't just give up and cause a
> system to reboot, that's a horrible way to write kernel code.

Fine, will drop the idea of WARN here.

Thanks,
Badal

>
> thanks,
>
> greg k-h