linux-hardening - [PATCH][next] wifi: mwifiex: Fix memcpy() field-spanning write warning in mwifiex_cmd_802_11_scan

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Message-ID: <ZsZa5xRcsLq9D+RX@elsanto>
Date: Wed, 21 Aug 2024 15:23:51 -0600
From: "Gustavo A. R. Silva" <gustavoars@...nel.org>
To: Brian Norris <briannorris@...omium.org>,
	Francesco Dolcini <francesco@...cini.it>,
	Kalle Valo <kvalo@...nel.org>,
	Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc: linux-wireless@...r.kernel.org, linux-kernel@...r.kernel.org,
	"Gustavo A. R. Silva" <gustavoars@...nel.org>,
	linux-hardening@...r.kernel.org
Subject: [PATCH][next] wifi: mwifiex: Fix memcpy() field-spanning write
 warning in mwifiex_cmd_802_11_scan_ext()

Replace one-element array with a flexible-array member in
`struct host_cmd_ds_802_11_scan_ext`.

With this, fix the following warning:

elo 16 17:51:58 surfacebook kernel: ------------[ cut here ]------------
elo 16 17:51:58 surfacebook kernel: memcpy: detected field-spanning write (size 243) of single field "ext_scan->tlv_buffer" at drivers/net/wireless/marvell/mwifiex/scan.c:2239 (size 1)
elo 16 17:51:58 surfacebook kernel: WARNING: CPU: 0 PID: 498 at drivers/net/wireless/marvell/mwifiex/scan.c:2239 mwifiex_cmd_802_11_scan_ext+0x83/0x90 [mwifiex]

Reported-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Closes: https://lore.kernel.org/linux-hardening/ZsZNgfnEwOcPdCly@black.fi.intel.com/
Signed-off-by: Gustavo A. R. Silva <gustavoars@...nel.org>
---
 drivers/net/wireless/marvell/mwifiex/fw.h   | 2 +-
 drivers/net/wireless/marvell/mwifiex/scan.c | 3 +--
 2 files changed, 2 insertions(+), 3 deletions(-)

diff --git a/drivers/net/wireless/marvell/mwifiex/fw.h b/drivers/net/wireless/marvell/mwifiex/fw.h
index e91def0afa14..d03129d5d24e 100644
--- a/drivers/net/wireless/marvell/mwifiex/fw.h
+++ b/drivers/net/wireless/marvell/mwifiex/fw.h
@@ -1627,7 +1627,7 @@ struct host_cmd_ds_802_11_scan_rsp {
 
 struct host_cmd_ds_802_11_scan_ext {
 	u32   reserved;
-	u8    tlv_buffer[1];
+	u8    tlv_buffer[];
 } __packed;
 
 struct mwifiex_ie_types_bss_mode {
diff --git a/drivers/net/wireless/marvell/mwifiex/scan.c b/drivers/net/wireless/marvell/mwifiex/scan.c
index e782d652cb93..f7153472e2a2 100644
--- a/drivers/net/wireless/marvell/mwifiex/scan.c
+++ b/drivers/net/wireless/marvell/mwifiex/scan.c
@@ -2536,8 +2536,7 @@ int mwifiex_ret_802_11_scan_ext(struct mwifiex_private *priv,
 	ext_scan_resp = &resp->params.ext_scan;
 
 	tlv = (void *)ext_scan_resp->tlv_buffer;
-	buf_left = le16_to_cpu(resp->size) - (sizeof(*ext_scan_resp) + S_DS_GEN
-					      - 1);
+	buf_left = le16_to_cpu(resp->size) - (sizeof(*ext_scan_resp) + S_DS_GEN);
 
 	while (buf_left >= sizeof(struct mwifiex_ie_types_header)) {
 		type = le16_to_cpu(tlv->type);
-- 
2.34.1