Re: [PATCH 04/15] ath10k: fix gcc-10 zero-length-bounds warnings

From: Kalle Valo
Date: Tue May 05 2020 - 00:56:24 EST


"Gustavo A. R. Silva" <gustavo@xxxxxxxxxxxxxx> writes:

> On 5/4/20 06:54, Kalle Valo wrote:
>> "Gustavo A. R. Silva" <gustavo@xxxxxxxxxxxxxx> writes:
>>
>>> Hi Arnd,
>>>
>>> On 4/30/20 16:30, Arnd Bergmann wrote:
>>>> gcc-10 started warning about out-of-bounds access for zero-length
>>>> arrays:
>>>>
>>>> In file included from drivers/net/wireless/ath/ath10k/core.h:18,
>>>> from drivers/net/wireless/ath/ath10k/htt_rx.c:8:
>>>> drivers/net/wireless/ath/ath10k/htt_rx.c: In function 'ath10k_htt_rx_tx_fetch_ind':
>>>> drivers/net/wireless/ath/ath10k/htt.h:1683:17: warning: array subscript 65535 is outside the bounds of an interior zero-length array 'struct htt_tx_fetch_record[0]' [-Wzero-length-bounds]
>>>> 1683 | return (void *)&ind->records[le16_to_cpu(ind->num_records)];
>>>> | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>>>> drivers/net/wireless/ath/ath10k/htt.h:1676:29: note: while referencing 'records'
>>>> 1676 | struct htt_tx_fetch_record records[0];
>>>> | ^~~~~~~
>>>>
>>>> The structure was already converted to have a flexible-array member in
>>>> the past, but there are two zero-length members in the end and only
>>>> one of them can be a flexible-array member.
>>>>
>>>> Swap the two around to avoid the warning, as 'resp_ids' is not accessed
>>>> in a way that causes a warning.
>>>>
>>>> Fixes: 3ba225b506a2 ("treewide: Replace zero-length array with flexible-array member")
>>>> Fixes: 22e6b3bc5d96 ("ath10k: add new htt definitions")
>>>> Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
>>>> ---
>>>> drivers/net/wireless/ath/ath10k/htt.h | 4 ++--
>>>> 1 file changed, 2 insertions(+), 2 deletions(-)
>>>>
>>>> diff --git a/drivers/net/wireless/ath/ath10k/htt.h b/drivers/net/wireless/ath/ath10k/htt.h
>>>> index e7096a73c6ca..7621f0a3dc77 100644
>>>> --- a/drivers/net/wireless/ath/ath10k/htt.h
>>>> +++ b/drivers/net/wireless/ath/ath10k/htt.h
>>>> @@ -1673,8 +1673,8 @@ struct htt_tx_fetch_ind {
>>>> __le32 token;
>>>> __le16 num_resp_ids;
>>>> __le16 num_records;
>>>> - struct htt_tx_fetch_record records[0];
>>>> - __le32 resp_ids[]; /* ath10k_htt_get_tx_fetch_ind_resp_ids() */
>>>> + __le32 resp_ids[0]; /* ath10k_htt_get_tx_fetch_ind_resp_ids() */
>>>> + struct htt_tx_fetch_record records[];
>>>> } __packed;
>>>>
>>>> static inline void *
>>>>
>>>
>>> The treewide patch is an experimental change and, as this change only applies
>>> to my -next tree, I will carry this patch in it, so other people don't have
>>> to worry about this at all.
>>
>> Gustavo, why do you have ath10k patches in your tree? I prefer that
>> ath10k patches go through my ath.git tree so that they are reviewed and
>> tested.
>>
>
> I just wanted to test out a mechanical change. I will remove it from my tree
> now and will send a patch to you so you can apply it to your ath.git tree.

Great, thanks.

--
https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches