linux-kernel - Re: [PATCH net-next 1/2] ath10k: fix gcc-10 zero-length-bounds warnings

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Date:   Sat, 9 May 2020 10:48:18 -0500
From:   "Gustavo A. R. Silva" <gustavoars@...nel.org>
To:     Arnd Bergmann <arnd@...db.de>
Cc:     Kalle Valo <kvalo@...eaurora.org>,
        "Gustavo A. R. Silva" <gustavo@...eddedor.com>,
        Michal Kazior <michal.kazior@...to.com>,
        Kalle Valo <kvalo@....qualcomm.com>,
        "David S. Miller" <davem@...emloft.net>,
        Wen Gong <wgong@...eaurora.org>,
        Erik Stromdahl <erik.stromdahl@...il.com>,
        ath10k@...ts.infradead.org, linux-wireless@...r.kernel.org,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH net-next 1/2] ath10k: fix gcc-10 zero-length-bounds
 warnings

Arnd,

On Sat, May 09, 2020 at 02:06:32PM +0200, 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];
>       |                             ^~~~~~~
> 
> Make records[] a flexible array member to allow this, moving it behind
> the other zero-length member that is not accessed in a way that gcc
> warns about.
> 
> Fixes: 3ba225b506a2 ("treewide: Replace zero-length array with flexible-array member")

This treewide patch no longer contains changes for ath10k. I removed them
since Monday (05/04/2020). So, this "Fixes" tag does not apply.

Thanks
--
Gustavo

> Fixes: 22e6b3bc5d96 ("ath10k: add new htt definitions")
> Signed-off-by: Arnd Bergmann <arnd@...db.de>
> ---
>  drivers/net/wireless/ath/ath10k/htt.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/net/wireless/ath/ath10k/htt.h b/drivers/net/wireless/ath/ath10k/htt.h
> index 8f3710cf28f4..aa056a186402 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[0]; /* ath10k_htt_get_tx_fetch_ind_resp_ids() */
> +	struct htt_tx_fetch_record records[];
>  } __packed;
>  
>  static inline void *
> -- 
> 2.26.0
>