linux-hardening - [PATCH v2 6/6][next] ath6kl: wmi: Replace one-element array with flexible-array member in struct wmi_aplist

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Date:   Thu, 24 Feb 2022 15:17:51 -0600
From:   "Gustavo A. R. Silva" <gustavoars@...nel.org>
To:     linux-wireless@...r.kernel.org, linux-kernel@...r.kernel.org,
        Jeff Johnson <quic_jjohnson@...cinc.com>
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,
        "Gustavo A. R. Silva" <gustavoars@...nel.org>
Subject: [PATCH v2 6/6][next] ath6kl: wmi: Replace one-element array with
 flexible-array member in struct wmi_aplist_event

Replace one-element array with flexible-array member in struct
wmi_aplist_event.

Also, make use of the struct_size() helper and remove unneeded variable
ap_info_entry_size.

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
Reviewed-by: Jeff Johnson <quic_jjohnson@...cinc.com>
Signed-off-by: Gustavo A. R. Silva <gustavoars@...nel.org>
---
Changes in v2:
 - Revert changes in if-statement logic:
        if (len < sizeof(struct wmi_aplist_event))
   Link: https://lore.kernel.org/linux-hardening/3f408c80-cabf-5ba2-2014-2eb0550b73f9@quicinc.com/
 - Update changelog text.
 - Add Reviewed-by: Jeff Johnson <quic_jjohnson@...cinc.com> tag.

 drivers/net/wireless/ath/ath6kl/wmi.c | 5 +----
 drivers/net/wireless/ath/ath6kl/wmi.h | 2 +-
 2 files changed, 2 insertions(+), 5 deletions(-)

diff --git a/drivers/net/wireless/ath/ath6kl/wmi.c b/drivers/net/wireless/ath/ath6kl/wmi.c
index bdfc057c5a82..3787b9fb0075 100644
--- a/drivers/net/wireless/ath/ath6kl/wmi.c
+++ b/drivers/net/wireless/ath/ath6kl/wmi.c
@@ -1750,7 +1750,6 @@ static int ath6kl_wmi_snr_threshold_event_rx(struct wmi *wmi, u8 *datap,
 
 static int ath6kl_wmi_aplist_event_rx(struct wmi *wmi, u8 *datap, int len)
 {
-	u16 ap_info_entry_size;
 	struct wmi_aplist_event *ev = (struct wmi_aplist_event *) datap;
 	struct wmi_ap_info_v1 *ap_info_v1;
 	u8 index;
@@ -1759,14 +1758,12 @@ static int ath6kl_wmi_aplist_event_rx(struct wmi *wmi, u8 *datap, int len)
 	    ev->ap_list_ver != APLIST_VER1)
 		return -EINVAL;
 
-	ap_info_entry_size = sizeof(struct wmi_ap_info_v1);
 	ap_info_v1 = (struct wmi_ap_info_v1 *) ev->ap_list;
 
 	ath6kl_dbg(ATH6KL_DBG_WMI,
 		   "number of APs in aplist event: %d\n", ev->num_ap);
 
-	if (len < (int) (sizeof(struct wmi_aplist_event) +
-			 (ev->num_ap - 1) * ap_info_entry_size))
+	if (len < struct_size(ev, ap_list, ev->num_ap))
 		return -EINVAL;
 
 	/* AP list version 1 contents */
diff --git a/drivers/net/wireless/ath/ath6kl/wmi.h b/drivers/net/wireless/ath/ath6kl/wmi.h
index 6a7fc07cd9aa..a9732660192a 100644
--- a/drivers/net/wireless/ath/ath6kl/wmi.h
+++ b/drivers/net/wireless/ath/ath6kl/wmi.h
@@ -1957,7 +1957,7 @@ union wmi_ap_info {
 struct wmi_aplist_event {
 	u8 ap_list_ver;
 	u8 num_ap;
-	union wmi_ap_info ap_list[1];
+	union wmi_ap_info ap_list[];
 } __packed;
 
 /* Developer Commands */
-- 
2.27.0