linux-kernel - [PATCH] wifi: rtw89: Correct immediate cfg_len calculation for scan_offload

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Message-Id: <20250108102512.3477461-1-buaajxlj@163.com>
Date: Wed,  8 Jan 2025 18:25:12 +0800
From: Liang Jie <buaajxlj@....com>
To: pkshih@...ltek.com
Cc: kvalo@...nel.org,
	phhuang@...ltek.com,
	linux-wireless@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Liang Jie <liangjie@...iang.com>
Subject: [PATCH] wifi: rtw89: Correct immediate cfg_len calculation for scan_offload_be

From: Liang Jie <liangjie@...iang.com>

This patch ensures the correct calculation of `cfg_len` prior to the
allocation of the skb in the `rtw89_fw_h2c_scan_offload_be` function,
particularly when the `SCAN_OFFLOAD_BE_V0` firmware feature is enabled.
It addresses an issue where an incorrect skb size might be allocated
due to a delayed setting of `cfg_len`, potentially leading to memory
inefficiencies.

By moving the conditional check and assignment of `cfg_len` before skb
allocation, the patch guarantees that `len`, which depends on `cfg_len`,
is accurately computed, ensuring proper skb size and preventing any
unnecessary memory reservation for firmware operations not supporting
beyond the `w8` member of the command data structure.

This correction helps to optimize memory usage and maintain consistent
behavior across different firmware versions.

Fixes: 6ca6b918f280 ("wifi: rtw89: 8922a: Add new fields for scan offload H2C command")

Signed-off-by: Liang Jie <liangjie@...iang.com>
---
 drivers/net/wireless/realtek/rtw89/fw.c | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/drivers/net/wireless/realtek/rtw89/fw.c b/drivers/net/wireless/realtek/rtw89/fw.c
index 2191c037d72e..5eb4beb9e485 100644
--- a/drivers/net/wireless/realtek/rtw89/fw.c
+++ b/drivers/net/wireless/realtek/rtw89/fw.c
@@ -5169,7 +5169,7 @@ int rtw89_fw_h2c_scan_offload_be(struct rtw89_dev *rtwdev,
 	u8 macc_role_size = sizeof(*macc_role) * option->num_macc_role;
 	u8 opch_size = sizeof(*opch) * option->num_opch;
 	u8 probe_id[NUM_NL80211_BANDS];
-	u8 cfg_len = sizeof(*h2c);
+	u8 cfg_len;
 	unsigned int cond;
 	void *ptr;
 	int ret;
@@ -5178,6 +5178,11 @@ int rtw89_fw_h2c_scan_offload_be(struct rtw89_dev *rtwdev,
 
 	rtw89_scan_get_6g_disabled_chan(rtwdev, option);
 
+	if (RTW89_CHK_FW_FEATURE(SCAN_OFFLOAD_BE_V0, &rtwdev->fw))
+		cfg_len = offsetofend(typeof(*h2c), w8);
+	else
+		cfg_len = sizeof(*h2c);
+
 	len = cfg_len + macc_role_size + opch_size;
 	skb = rtw89_fw_h2c_alloc_skb_with_hdr(rtwdev, len);
 	if (!skb) {
@@ -5246,10 +5251,8 @@ int rtw89_fw_h2c_scan_offload_be(struct rtw89_dev *rtwdev,
 					   RTW89_H2C_SCANOFLD_BE_W8_PROBE_RATE_6GHZ);
 	}
 
-	if (RTW89_CHK_FW_FEATURE(SCAN_OFFLOAD_BE_V0, &rtwdev->fw)) {
-		cfg_len = offsetofend(typeof(*h2c), w8);
+	if (RTW89_CHK_FW_FEATURE(SCAN_OFFLOAD_BE_V0, &rtwdev->fw))
 		goto flex_member;
-	}
 
 	h2c->w9 = le32_encode_bits(sizeof(*h2c) / sizeof(h2c->w0),
 				   RTW89_H2C_SCANOFLD_BE_W9_SIZE_CFG) |
-- 
2.25.1