linux-hardening - Re: [PATCH v2][next] wifi: wil6210: Annotate a couple of structs with __counted

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Date: Wed, 27 Mar 2024 12:39:54 -0600
From: "Gustavo A. R. Silva" <gustavo@...eddedor.com>
To: Jeff Johnson <quic_jjohnson@...cinc.com>,
 "Gustavo A. R. Silva" <gustavoars@...nel.org>, Kalle Valo <kvalo@...nel.org>
Cc: linux-wireless@...r.kernel.org, linux-kernel@...r.kernel.org,
 linux-hardening@...r.kernel.org
Subject: Re: [PATCH v2][next] wifi: wil6210: Annotate a couple of structs with
 __counted_by()


>>>   #define WMI_MAX_PNO_SSID_NUM    (16)
>>> @@ -3320,7 +3320,7 @@ struct wmi_set_link_monitor_cmd {
>>>       u8 rssi_hyst;
>>>       u8 reserved[12];
>>>       u8 rssi_thresholds_list_size;
>>> -    s8 rssi_thresholds_list[];
>>> +    s8 rssi_thresholds_list[] __counted_by(rssi_thresholds_list_size);
>>>   } __packed;
>>
>> this looks ok to me, although I think there is another issue associated with
>> this, namely the way the code populates the rssi_thresholds_list is by
>> defining a separate anonymous struct:
>>     struct {
>>         struct wmi_set_link_monitor_cmd cmd;
>>         s8 rssi_thold;
>>     } __packed cmd = {
>>         .cmd = {
>>             .rssi_hyst = rssi_hyst,
>>             .rssi_thresholds_list_size = 1,
>>         },
>>         .rssi_thold = rssi_thold,
>>     };
>>
>> I would expect gcc and clang to both complain about that s8 rssi_thold comes
>> after a flexible array (even though its purpose is to be the value of
>> rssi_thresholds_list[0])
>>

I will merge these two patches together:

https://lore.kernel.org/linux-hardening/ZgODZOB4fOBvKl7R@neat/
https://lore.kernel.org/linux-hardening/ZgOEoCWguq3n1OqQ@neat/

and send these changes together with the DEFINE_FLEX() transformation
in drivers/net/wireless/ath/wil6210/cfg80211.c

diff --git a/drivers/net/wireless/ath/wil6210/wmi.h b/drivers/net/wireless/ath/wil6210/wmi.h
index 71bf2ae27a98..38f64524019e 100644
--- a/drivers/net/wireless/ath/wil6210/wmi.h
+++ b/drivers/net/wireless/ath/wil6210/wmi.h
@@ -474,7 +474,7 @@ struct wmi_start_scan_cmd {
       struct {
           u8 channel;
           u8 reserved;
-    } channel_list[];
+    } channel_list[] __counted_by(num_channels);
   } __packed;

Thanks
--
Gustavo