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

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Date:   Tue, 22 Feb 2022 20:38:31 -0600
From:   "Gustavo A. R. Silva" <gustavoars@...nel.org>
To:     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,
        "Gustavo A. R. Silva" <gustavoars@...nel.org>
Subject: [PATCH 1/6][next] ath6kl: wmi: Replace one-element array with
 flexible-array member in struct wmi_begin_scan_cmd

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
-- 
2.27.0