Re: [PATCH] wifi: brcmfmac: Adjust n_channels usage for __counted_by

[Arend Van Spriel <aspriel@gmail.com>]

On 2/2/2024 11:34 AM, Kalle Valo wrote:
> Arend Van Spriel <aspriel@gmail.com> writes:
> 
>> On 2/2/2024 10:58 AM, Arend Van Spriel wrote:
>>
>>> On 2/1/2024 11:04 AM, Kalle Valo wrote:
>>>> Kees Cook <keescook@chromium.org> wrote:
>>>>
>>>>> After commit e3eac9f32ec0 ("wifi: cfg80211: Annotate struct
>>>>> cfg80211_scan_request with __counted_by"), the compiler may enforce
>>>>> dynamic array indexing of req->channels to stay below n_channels. As a
>>>>> result, n_channels needs to be increased _before_ accessing the newly
>>>>> added array index. Increment it first, then use "i" for the prior index.
>>>>> Solves this warning in the coming GCC that has __counted_by support:
>>>>>
>>>>> ../drivers/net/wireless/broadcom/brcm80211/brcmfmac/cfg80211.c: In
>>>>> function 'brcmf_internal_escan_add_info':
>>>>> ../drivers/net/wireless/broadcom/brcm80211/brcmfmac/cfg80211.c:3783:46: warning: operation on 'req->
>>>>> n_channels' may be undefined [-Wsequence-point]
>>>>>    3783 |                 req->channels[req->n_channels++] = chan;
>>>>>         |                               ~~~~~~~~~~~~~~~^~
>>>>>
>>>>> Fixes: e3eac9f32ec0 ("wifi: cfg80211: Annotate struct
>>>>> cfg80211_scan_request with __counted_by")
>>>>> Cc: Arend van Spriel <aspriel@gmail.com>
>>>>> Cc: Franky Lin <franky.lin@broadcom.com>
>>>>> Cc: Hante Meuleman <hante.meuleman@broadcom.com>
>>>>> Cc: Kalle Valo <kvalo@kernel.org>
>>>>> Cc: Chi-hsien Lin <chi-hsien.lin@infineon.com>
>>>>> Cc: Ian Lin <ian.lin@infineon.com>
>>>>> Cc: Johannes Berg <johannes.berg@intel.com>
>>>>> Cc: Wright Feng <wright.feng@cypress.com>
>>>>> Cc: Hector Martin <marcan@marcan.st>
>>>>> Cc: linux-wireless@vger.kernel.org
>>>>> Cc: brcm80211-dev-list.pdl@broadcom.com
>>>>> Signed-off-by: Kees Cook <keescook@chromium.org>
>>>>> Reviewed-by: Hans de Goede <hdegoede@redhat.com>
>>>>> Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
>>>>> Reviewed-by: Gustavo A. R. Silva <gustavoars@kernel.org>
>>>>
>>>> I'm planning to queue this for wireless tree. Arend, ack?
>>> This slipped past my broadcom email. As the Fixes commit is in 6.7 I
>>> would say ACK.
> 
> Thanks.
> 
>> Cc: to stable?
> 
> Is commit e3eac9f32ec0 in stable releases? (I don't follow stable and
> don't know what commits they take.) I propose that as we have Fixes tag
> let's not add cc but instead let stable maintainers to decide.

I confirmed the commit was in 6.7 and the latest released kernel is 
always handled by stable kernel team. kernel.org main page always shows 
the active stable/longterm releases. That said I have no problem with 
your proposal.

Gr. AvS