wifi: mwifiex: Fix memcpy() field-spanning write warning in mwifiex_c…

…md_802_11_scan_ext()

[ Upstream commit 498365e ]

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@linux.intel.com>
Closes: https://lore.kernel.org/linux-hardening/ZsZNgfnEwOcPdCly@black.fi.intel.com/
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: Brian Norris <briannorris@chromium.org>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://patch.msgid.link/ZsZa5xRcsLq9D+RX@elsanto
Signed-off-by: Sasha Levin <sashal@kernel.org>

drivers/net/wireless/marvell/mwifiex/fw.h

@@ -1586,7 +1586,7 @@ 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 {

drivers/net/wireless/marvell/mwifiex/scan.c

@@ -2548,8 +2548,7 @@ 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);