linux-hardening - [PATCH][next] mwifiex: usb: Replace one-element array with flexible-array member

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Date:   Mon, 9 Aug 2021 16:11:34 -0500
From:   "Gustavo A. R. Silva" <gustavoars@...nel.org>
To:     Amitkumar Karwar <amitkarwar@...il.com>,
        Ganapathi Bhat <ganapathi017@...il.com>,
        Sharvari Harisangam <sharvari.harisangam@....com>,
        Xinming Hu <huxinming820@...il.com>,
        Kalle Valo <kvalo@...eaurora.org>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>
Cc:     linux-wireless@...r.kernel.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        "Gustavo A. R. Silva" <gustavoars@...nel.org>,
        linux-hardening@...r.kernel.org
Subject: [PATCH][next] mwifiex: usb: Replace one-element array with
 flexible-array member

There is a regular need in the kernel to provide a way to declare having
a dynamically sized set of trailing elements in a structure. Kernel code
should always use “flexible array members”[1] for these cases. The older
style of one-element or zero-length arrays should no longer be used[2].

This helps with the ongoing efforts to globally enable -Warray-bounds
and get us closer to being able to tighten the FORTIFY_SOURCE routines
on memcpy().

This issue was found with the help of Coccinelle and audited and fixed,
manually.

[1] https://en.wikipedia.org/wiki/Flexible_array_member
[2] https://www.kernel.org/doc/html/v5.10/process/deprecated.html#zero-length-and-one-element-arrays

Link: https://github.com/KSPP/linux/issues/79
Link: https://github.com/KSPP/linux/issues/109
Signed-off-by: Gustavo A. R. Silva <gustavoars@...nel.org>
---
 drivers/net/wireless/marvell/mwifiex/usb.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/wireless/marvell/mwifiex/usb.h b/drivers/net/wireless/marvell/mwifiex/usb.h
index d822ec15b7e6..61a96b7fbf21 100644
--- a/drivers/net/wireless/marvell/mwifiex/usb.h
+++ b/drivers/net/wireless/marvell/mwifiex/usb.h
@@ -134,7 +134,7 @@ struct fw_sync_header {
 struct fw_data {
 	struct fw_header fw_hdr;
 	__le32 seq_num;
-	u8 data[1];
+	u8 data[];
 } __packed;
 
 #endif /*_MWIFIEX_USB_H */
-- 
2.27.0