Re: [PATCH v2][next] wifi: wil6210: Annotate a couple of structs with __counted_by()

From: Gustavo A. R. Silva
Date: Wed Mar 27 2024 - 14:40:04 EST



  #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