On 10/24/23 14:49, Johannes Berg wrote:
> On Tue, 2023-10-24 at 14:41 -0600, Gustavo A. R. Silva wrote:
>>
>> It seems we run into the same issue in the function below, even in the
>> case this `memset()` is unnecessary (which it seems it's not):
>>
>> 8920 memset(skb->data, 0, sizeof(*cmd));
>>
>> Notice that if `cap->peer_chan_len == 0` or `cap->peer_chan_len == 1`,
>> in the original code, we have `len == sizeof(*cmd) == 128`:
>
> Right.
>
>> - /* tdls peer update cmd has place holder for one channel*/
>> - chan_len = cap->peer_chan_len ? (cap->peer_chan_len - 1) : 0;
>> -
>> - len = sizeof(*cmd) + chan_len * sizeof(*chan);
>> + len = struct_size(cmd, peer_capab.peer_chan_list, cap->peer_chan_len);
>>
>> skb = ath10k_wmi_alloc_skb(ar, len);
>> if (!skb)
>>
>> which makes `round_len == roundup(len, 4) == struct_size(cmd,...,...) == 104`
>> when `cap->peer_chan_len == 0`
>
> And yeah, that's really the issue, it only matters for ==0. For a moment
> there I thought that doesn't even make sense, but it looks like it never
> even becomes non-zero.
>
> No idea then, sorry. You'd hope firmware doesn't care about the actual
> message size if the inner data says "0 entries", but who knows? And how
> many firmware versions are there? :)
>
> So I guess you'd want to stay compatible, even if it means having a
>
> chan_len = min(cap->peer_chan_len, 1);
>
> for the struct_size()?
Yeah, that's an alternative.
I'll wait for the maintainers to chime in and see if they have a different
opinion.
Thanks
--
Gustavo
On 10/24/2023 7:37 PM, Gustavo A. R. Silva wrote:
>
>
> On 10/24/23 14:49, Johannes Berg wrote:
>> On Tue, 2023-10-24 at 14:41 -0600, Gustavo A. R. Silva wrote:
>>>
>>> It seems we run into the same issue in the function below, even in the
>>> case this `memset()` is unnecessary (which it seems it's not):
>>>
>>> 8920 memset(skb->data, 0, sizeof(*cmd));
>>>
>>> Notice that if `cap->peer_chan_len == 0` or `cap->peer_chan_len == 1`,
>>> in the original code, we have `len == sizeof(*cmd) == 128`:
>>
>> Right.
>>
>>> - /* tdls peer update cmd has place holder for one channel*/
>>> - chan_len = cap->peer_chan_len ? (cap->peer_chan_len - 1) : 0;
>>> -
>>> - len = sizeof(*cmd) + chan_len * sizeof(*chan);
>>> + len = struct_size(cmd, peer_capab.peer_chan_list,
>>> cap->peer_chan_len);
>>>
>>> skb = ath10k_wmi_alloc_skb(ar, len);
>>> if (!skb)
>>>
>>> which makes `round_len == roundup(len, 4) == struct_size(cmd,...,...)
>>> == 104`
>>> when `cap->peer_chan_len == 0`
>>
>> And yeah, that's really the issue, it only matters for ==0. For a moment
>> there I thought that doesn't even make sense, but it looks like it never
>> even becomes non-zero.
>>
>> No idea then, sorry. You'd hope firmware doesn't care about the actual
>> message size if the inner data says "0 entries", but who knows? And how
>> many firmware versions are there? :)
>>
>> So I guess you'd want to stay compatible, even if it means having a
>>
>> chan_len = min(cap->peer_chan_len, 1);
>>
>> for the struct_size()?
>
> Yeah, that's an alternative.
>
> I'll wait for the maintainers to chime in and see if they have a different
> opinion.
I'm seeing clarification from the development team.
/jeff