linux-hardening - [PATCH 4/6][next] ath6kl: wmi: Replace one-element array with flexible-array member in struct wmi_connect

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Date:   Tue, 22 Feb 2022 20:38:57 -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 4/6][next] ath6kl: wmi: Replace one-element array with
 flexible-array  member in struct wmi_connect_event

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

It's also worth noting that due to the flexible array transformation,
the size of struct wmi_connect_event changed (now the size is 1 byte
smaller), and in order to preserve the logic of before the transformation,
the following change is needed:

	-       if (len < sizeof(struct wmi_connect_event))
	+       if (len <= sizeof(struct wmi_connect_event))

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>
---
Hi!

It'd be great if someone can confirm or comment on the following
changes described in the changelog text:

        -       if (len < sizeof(struct wmi_connect_event))
        +       if (len <= sizeof(struct wmi_connect_event))

Thanks

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

diff --git a/drivers/net/wireless/ath/ath6kl/wmi.c b/drivers/net/wireless/ath/ath6kl/wmi.c
index 049d75f31f3c..ccdccead688e 100644
--- a/drivers/net/wireless/ath/ath6kl/wmi.c
+++ b/drivers/net/wireless/ath/ath6kl/wmi.c
@@ -857,7 +857,7 @@ static int ath6kl_wmi_connect_event_rx(struct wmi *wmi, u8 *datap, int len,
 	struct wmi_connect_event *ev;
 	u8 *pie, *peie;
 
-	if (len < sizeof(struct wmi_connect_event))
+	if (len <= sizeof(struct wmi_connect_event))
 		return -EINVAL;
 
 	ev = (struct wmi_connect_event *) datap;
diff --git a/drivers/net/wireless/ath/ath6kl/wmi.h b/drivers/net/wireless/ath/ath6kl/wmi.h
index 432e4f428a4a..6b064e669d87 100644
--- a/drivers/net/wireless/ath/ath6kl/wmi.h
+++ b/drivers/net/wireless/ath/ath6kl/wmi.h
@@ -1545,7 +1545,7 @@ struct wmi_connect_event {
 	u8 beacon_ie_len;
 	u8 assoc_req_len;
 	u8 assoc_resp_len;
-	u8 assoc_info[1];
+	u8 assoc_info[];
 } __packed;
 
 /* Disconnect Event */
-- 
2.27.0