[PATCH v3 2/3] wifi: rtl8xxxu: Fix the channel width reporting

[Bitterblue Smith <rtl8821cerfe2@gmail.com>]

The gen 2 chips RTL8192EU and RTL8188FU periodically send the driver
reports about the TX rate, and the driver passes these reports to
sta_statistics. The reports from RTL8192EU may or may not include the
channel width. The reports from RTL8188FU do not include it.

Only access the c2h->ra_report.bw field if the report (skb) is big
enough.

The other problem fixed here is that the code was actually never
changing the channel width initially reported by
rtl8xxxu_bss_info_changed because the value of RATE_INFO_BW_20 is 0.

Fixes: 0985d3a410ac ("rtl8xxxu: Feed current txrate information for mac80211")
Signed-off-by: Bitterblue Smith <rtl8821cerfe2@gmail.com>
---
v3:
 - Don't assume bw will always be 1 byte.
 
v2:
 - Eliminate the magic numbers.
---
 drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu_core.c | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu_core.c b/drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu_core.c
index 28f136064297..9799bc5ed60a 100644
--- a/drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu_core.c
+++ b/drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu_core.c
@@ -5569,7 +5569,6 @@ static void rtl8xxxu_c2hcmd_callback(struct work_struct *work)
 			rarpt->txrate.flags = 0;
 			rate = c2h->ra_report.rate;
 			sgi = c2h->ra_report.sgi;
-			bw = c2h->ra_report.bw;
 
 			if (rate < DESC_RATE_MCS0) {
 				rarpt->txrate.legacy =
@@ -5586,8 +5585,14 @@ static void rtl8xxxu_c2hcmd_callback(struct work_struct *work)
 						RATE_INFO_FLAGS_SHORT_GI;
 				}
 
-				if (bw == RATE_INFO_BW_20)
-					rarpt->txrate.bw |= RATE_INFO_BW_20;
+				if (skb->len >= offsetof(typeof(*c2h), ra_report.bw) +
+						sizeof(c2h->ra_report.bw)) {
+					if (c2h->ra_report.bw == RTL8XXXU_CHANNEL_WIDTH_40)
+						bw = RATE_INFO_BW_40;
+					else
+						bw = RATE_INFO_BW_20;
+					rarpt->txrate.bw = bw;
+				}
 			}
 			bit_rate = cfg80211_calculate_bitrate(&rarpt->txrate);
 			rarpt->bit_rate = bit_rate;
-- 
2.38.0