netdev - Re: [PATCH] brcmfmac: Replace zero-length array with flexible array member

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Message-ID: <20210912191536.GB146608@embeddedor>
Date:   Sun, 12 Sep 2021 14:15:36 -0500
From:   "Gustavo A. R. Silva" <gustavoars@...nel.org>
To:     Len Baker <len.baker@....com>
Cc:     Arend van Spriel <aspriel@...il.com>,
        Franky Lin <franky.lin@...adcom.com>,
        Hante Meuleman <hante.meuleman@...adcom.com>,
        Chi-hsien Lin <chi-hsien.lin@...ineon.com>,
        Wright Feng <wright.feng@...ineon.com>,
        Chung-hsien Hsu <chung-hsien.hsu@...ineon.com>,
        Kalle Valo <kvalo@...eaurora.org>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        "Gustavo A. R. Silva" <gustavo@...eddedor.com>,
        Kees Cook <keescook@...omium.org>,
        Shawn Guo <shawn.guo@...aro.org>,
        linux-wireless@...r.kernel.org,
        brcm80211-dev-list.pdl@...adcom.com,
        SHA-cyfmac-dev-list@...ineon.com, netdev@...r.kernel.org,
        linux-hardening@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] brcmfmac: Replace zero-length array with flexible array
 member

On Sat, Sep 04, 2021 at 11:22:17AM +0200, Len Baker wrote:
> There is a regular need in the kernel to provide a way to declare
> having a dynamically sized set of trailing elements in a structure.
> Kernel code should always use "flexible array members"[1] for these
> cases. The older style of one-element or zero-length arrays should
> no longer be used[2].
> 
> Also, make use of the struct_size() helper in devm_kzalloc().
> 
> [1] https://en.wikipedia.org/wiki/Flexible_array_member
> [2] https://www.kernel.org/doc/html/v5.14/process/deprecated.html#zero-length-and-one-element-arrays
> 
> Signed-off-by: Len Baker <len.baker@....com>

Reviewed-by: Gustavo A. R. Silva <gustavoars@...nel.org>

I'll take this in my -next tree. :)

Thanks, Len.
--
Gustavo

> ---
>  drivers/net/wireless/broadcom/brcm80211/brcmfmac/of.c | 2 +-
>  include/linux/platform_data/brcmfmac.h                | 2 +-
>  2 files changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/of.c b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/of.c
> index 2f7bc3a70c65..513c7e6421b2 100644
> --- a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/of.c
> +++ b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/of.c
> @@ -29,7 +29,7 @@ static int brcmf_of_get_country_codes(struct device *dev,
>  		return (count == -EINVAL) ? 0 : count;
>  	}
> 
> -	cc = devm_kzalloc(dev, sizeof(*cc) + count * sizeof(*cce), GFP_KERNEL);
> +	cc = devm_kzalloc(dev, struct_size(cc, table, count), GFP_KERNEL);
>  	if (!cc)
>  		return -ENOMEM;
> 
> diff --git a/include/linux/platform_data/brcmfmac.h b/include/linux/platform_data/brcmfmac.h
> index 1d30bf278231..2b5676ff35be 100644
> --- a/include/linux/platform_data/brcmfmac.h
> +++ b/include/linux/platform_data/brcmfmac.h
> @@ -125,7 +125,7 @@ struct brcmfmac_pd_cc_entry {
>   */
>  struct brcmfmac_pd_cc {
>  	int				table_size;
> -	struct brcmfmac_pd_cc_entry	table[0];
> +	struct brcmfmac_pd_cc_entry	table[];
>  };
> 
>  /**
> --
> 2.25.1
>