Re: [PATCH 1/3] wifi: ipw2x00: convert ipw_fw_error->elem to flexible array[]

[Jacob Keller <jacob.e.keller@intel.com>]

On 2/28/2023 9:46 AM, Johannes Berg wrote:
> On Tue, 2023-02-28 at 09:44 -0800, Jacob Keller wrote:
>>
>> Previous to this change, error struct has two pointers to sections of
>> memory allocated at the end of the buffer.
>>
>> The code used to be:
>>
>> -	error = kmalloc(sizeof(*error) +
>> -			sizeof(*error->elem) * elem_len +
>> -			sizeof(*error->log) * log_len, GFP_ATOMIC);
>>
>> i.e. the elem_len is multiplying sizeof(*error->elem).
>>
>> The code is essentially trying to get two flexible arrays in the same
>> allocation, and its a bit messy to do that. I don't see how elem_len
>> could be anything other than "number of elems" given this code I removed.
> 
> Yeah, you're right. I was thinking of more modern HW/FW too much I
> guess, I see now even in the driver we have an array walk here (and it
> trusts the elem_len from firmware... ahrg!)
> 
>> I posted these mainly because I was trying to resolve all of the hits
>> that were found by the coccinelle patch I made, posted at [1]. I wanted
>> to get it to run clean so that we had no more struct_size hits.
>>
>> Dropping this would just make that patch have some hits until the driver
>> is removed, eventually...
>>
>> Not really a big deal to me, I just didn't want to post a coccinelle
>> patch without also trying to fix the handful of problems it reported,
>> since the total number of reports was small.
>>
> 
> Makes sense. I don't think we'll drop the driver at any point soon, but
> I also don't see it being changed much :)
> 
> johannes

I can drop this one out of the series if you don't have an intention of
taking it, or I can refactor to just use size_add and array_size without
converting it to flexible array, which would prevent that coccinelle
patch from complaining and at least ensure that we can't overflow size
and under-allocate.

Do you have a preference?

Thanks,
Jake