linux-hardening - Re: [PATCH v2][next] wifi: ath6kl: wmi: Avoid -Wflex-array-member-not-at-end warning

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Message-ID: <6305fbc7-8210-4f4d-b719-30ba038611af@embeddedor.com>
Date: Wed, 18 Feb 2026 18:38:41 +0900
From: "Gustavo A. R. Silva" <gustavo@...eddedor.com>
To: Jeff Johnson <jeff.johnson@....qualcomm.com>,
 "Gustavo A. R. Silva" <gustavoars@...nel.org>,
 Kalle Valo <quic_kvalo@...cinc.com>
Cc: linux-wireless@...r.kernel.org, linux-kernel@...r.kernel.org,
 linux-hardening@...r.kernel.org
Subject: Re: [PATCH v2][next] wifi: ath6kl: wmi: Avoid
 -Wflex-array-member-not-at-end warning


>> @@ -1652,7 +1656,7 @@ struct roam_ctrl_cmd {
>>   	union {
>>   		u8 bssid[ETH_ALEN]; /* WMI_FORCE_ROAM */
>>   		u8 roam_mode; /* WMI_SET_ROAM_MODE */
>> -		struct bss_bias_info bss; /* WMI_SET_HOST_BIAS */
>> +		struct bss_bias_info_hdr bss; /* WMI_SET_HOST_BIAS */
>>   		struct low_rssi_scan_params params; /* WMI_SET_LRSSI_SCAN_PARAMS
>>   						     */
>>   	} __packed info;
> 
> That bss member appears to be completely unused
> (bssid, roam_mode, and params are used)
> 
> So IMO the better solution is to remove bss from the union.
> And I think struct bss_bias and struct bss_bias_info can also be removed.

Even if they're not used, are you sure they aren't there simply	
to define the memory layout of struct roam_ctrl_cmd?

As Kees commented[1], struct roam_ctrl_cmd appears to be a
hardware interface... See below:

drivers/net/wireless/ath/ath6kl/wmi.c:
  755 /*
  756  * Mechanism to modify the roaming behavior in the firmware. The lower rssi
  757  * at which the station has to roam can be passed with
  758  * WMI_SET_LRSSI_SCAN_PARAMS. Subtract 96 from RSSI to get the signal level
  759  * in dBm.
  760  */
  761 int ath6kl_wmi_set_roam_lrssi_cmd(struct wmi *wmi, u8 lrssi)
  762 {
  763         struct sk_buff *skb;
  764         struct roam_ctrl_cmd *cmd;
  765
  766         skb = ath6kl_wmi_get_new_buf(sizeof(*cmd));
  767         if (!skb)
  768                 return -ENOMEM;
  769
  770         cmd = (struct roam_ctrl_cmd *) skb->data;
...
}

Thanks
-Gustavo

[1] https://lore.kernel.org/linux-hardening/202601151627.99DFE54@keescook/