linux-hardening - Re: [PATCH 1/6][next] ath6kl: wmi: Replace one-element array with flexible-array member in struct wmi_begin_scan

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Date:   Wed, 23 Feb 2022 16:48:04 -0800
From:   Jeff Johnson <quic_jjohnson@...cinc.com>
To:     "Gustavo A. R. Silva" <gustavoars@...nel.org>,
        <linux-wireless@...r.kernel.org>, <linux-kernel@...r.kernel.org>
CC:     Kalle Valo <kvalo@...nel.org>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>, <netdev@...r.kernel.org>,
        <linux-hardening@...r.kernel.org>
Subject: Re: [PATCH 1/6][next] ath6kl: wmi: Replace one-element array with
 flexible-array member in struct wmi_begin_scan_cmd

On 2/22/2022 6:38 PM, Gustavo A. R. Silva wrote:
> Replace one-element array with flexible-array member in struct
> wmi_begin_scan_cmd. Also, make use of the struct_size() helper.
> 
> This issue was found with the help of Coccinelle and audited and fixed,
> manually.
> 
> Link: https://www.kernel.org/doc/html/v5.16/process/deprecated.html#zero-length-and-one-element-arrays
> Link: https://github.com/KSPP/linux/issues/79
> Signed-off-by: Gustavo A. R. Silva <gustavoars@...nel.org>
> ---
>   drivers/net/wireless/ath/ath6kl/wmi.c | 9 ++-------
>   drivers/net/wireless/ath/ath6kl/wmi.h | 2 +-
>   2 files changed, 3 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/net/wireless/ath/ath6kl/wmi.c b/drivers/net/wireless/ath/ath6kl/wmi.c
> index bd1ef6334997..e1c950014f3e 100644
> --- a/drivers/net/wireless/ath/ath6kl/wmi.c
> +++ b/drivers/net/wireless/ath/ath6kl/wmi.c
> @@ -2008,7 +2008,7 @@ int ath6kl_wmi_beginscan_cmd(struct wmi *wmi, u8 if_idx,
>   	struct ieee80211_supported_band *sband;
>   	struct sk_buff *skb;
>   	struct wmi_begin_scan_cmd *sc;
> -	s8 size, *supp_rates;
> +	s8 *supp_rates;
>   	int i, band, ret;
>   	struct ath6kl *ar = wmi->parent_dev;
>   	int num_rates;
> @@ -2023,18 +2023,13 @@ int ath6kl_wmi_beginscan_cmd(struct wmi *wmi, u8 if_idx,
>   						num_chan, ch_list);
>   	}
>   
> -	size = sizeof(struct wmi_begin_scan_cmd);
> -
>   	if ((scan_type != WMI_LONG_SCAN) && (scan_type != WMI_SHORT_SCAN))
>   		return -EINVAL;
>   
>   	if (num_chan > WMI_MAX_CHANNELS)
>   		return -EINVAL;
>   
> -	if (num_chan)
> -		size += sizeof(u16) * (num_chan - 1);
> -
> -	skb = ath6kl_wmi_get_new_buf(size);
> +	skb = ath6kl_wmi_get_new_buf(struct_size(sc, ch_list, num_chan));
>   	if (!skb)
>   		return -ENOMEM;
>   
> diff --git a/drivers/net/wireless/ath/ath6kl/wmi.h b/drivers/net/wireless/ath/ath6kl/wmi.h
> index 784940ba4c90..322539ed9c12 100644
> --- a/drivers/net/wireless/ath/ath6kl/wmi.h
> +++ b/drivers/net/wireless/ath/ath6kl/wmi.h
> @@ -863,7 +863,7 @@ struct wmi_begin_scan_cmd {
>   	u8 num_ch;
>   
>   	/* channels in Mhz */
> -	__le16 ch_list[1];
> +	__le16 ch_list[];
>   } __packed;
>   
>   /* wmi_start_scan_cmd is to be deprecated. Use



Reviewed-by: Jeff Johnson <quic_jjohnson@...cinc.com>