mt76: mt7915: fix txrate reporting

Properly check rate_info to fix unexpected reporting.

[ 1215.161863] Call trace:
[ 1215.164307]  cfg80211_calculate_bitrate+0x124/0x200 [cfg80211]
[ 1215.170139]  ieee80211s_update_metric+0x80/0xc0 [mac80211]
[ 1215.175624]  ieee80211_tx_status_ext+0x508/0x838 [mac80211]
[ 1215.181190]  mt7915_mcu_get_rx_rate+0x28c/0x8d0 [mt7915e]
[ 1215.186580]  mt7915_mac_tx_free+0x324/0x7c0 [mt7915e]
[ 1215.191623]  mt7915_queue_rx_skb+0xa8/0xd0 [mt7915e]
[ 1215.196582]  mt76_dma_cleanup+0x7b0/0x11d0 [mt76]
[ 1215.201276]  __napi_poll+0x38/0xf8
[ 1215.204668]  napi_workfn+0x40/0x80
[ 1215.208062]  process_one_work+0x1fc/0x390
[ 1215.212062]  worker_thread+0x48/0x4d0
[ 1215.215715]  kthread+0x120/0x128
[ 1215.218935]  ret_from_fork+0x10/0x1c

Fixes: e57b7901 ("mt76: add mac80211 driver for MT7915 PCIe-based chipsets")
Fixes: e4c5ead6 ("mt76: mt7915: rename mt7915_mcu_get_rate_info to mt7915_mcu_get_tx_rate")
Reported-by: Evelyn Tsai <evelyn.tsai@mediatek.com>
Signed-off-by: Ryder Lee <ryder.lee@mediatek.com>
Signed-off-by: Felix Fietkau <nbd@nbd.name>

drivers/net/wireless/mediatek/mt76/mt7915/mcu.c

@@ -364,54 +364,62 @@ mt7915_mcu_rx_radar_detected(struct mt7915_dev *dev, struct sk_buff *skb)
 	dev->hw_pattern++;
 }
 
-static void
+static int
 mt7915_mcu_tx_rate_parse(struct mt76_phy *mphy, struct mt7915_mcu_ra_info *ra,
 			 struct rate_info *rate, u16 r)
 {
 	struct ieee80211_supported_band *sband;
 	u16 ru_idx = le16_to_cpu(ra->ru_idx);
-	u16 flags = 0;
+	bool cck = false;
 
 	rate->mcs = FIELD_GET(MT_RA_RATE_MCS, r);
 	rate->nss = FIELD_GET(MT_RA_RATE_NSS, r) + 1;
 
 	switch (FIELD_GET(MT_RA_RATE_TX_MODE, r)) {
 	case MT_PHY_TYPE_CCK:
+		cck = true;
+		fallthrough;
 	case MT_PHY_TYPE_OFDM:
 		if (mphy->chandef.chan->band == NL80211_BAND_5GHZ)
 			sband = &mphy->sband_5g.sband;
 		else
 			sband = &mphy->sband_2g.sband;
 
+		rate->mcs = mt76_get_rate(mphy->dev, sband, rate->mcs, cck);
 		rate->legacy = sband->bitrates[rate->mcs].bitrate;
 		break;
 	case MT_PHY_TYPE_HT:
 	case MT_PHY_TYPE_HT_GF:
 		rate->mcs += (rate->nss - 1) * 8;
-		flags |= RATE_INFO_FLAGS_MCS;
+		if (rate->mcs > 31)
+			return -EINVAL;
 
+		rate->flags = RATE_INFO_FLAGS_MCS;
 		if (ra->gi)
-			flags |= RATE_INFO_FLAGS_SHORT_GI;
+			rate->flags |= RATE_INFO_FLAGS_SHORT_GI;
 		break;
 	case MT_PHY_TYPE_VHT:
-		flags |= RATE_INFO_FLAGS_VHT_MCS;
+		if (rate->mcs > 9)
+			return -EINVAL;
 
+		rate->flags = RATE_INFO_FLAGS_VHT_MCS;
 		if (ra->gi)
-			flags |= RATE_INFO_FLAGS_SHORT_GI;
+			rate->flags |= RATE_INFO_FLAGS_SHORT_GI;
 		break;
 	case MT_PHY_TYPE_HE_SU:
 	case MT_PHY_TYPE_HE_EXT_SU:
 	case MT_PHY_TYPE_HE_TB:
 	case MT_PHY_TYPE_HE_MU:
+		if (ra->gi > NL80211_RATE_INFO_HE_GI_3_2 || rate->mcs > 11)
+			return -EINVAL;
+
 		rate->he_gi = ra->gi;
 		rate->he_dcm = FIELD_GET(MT_RA_RATE_DCM_EN, r);
-
-		flags |= RATE_INFO_FLAGS_HE_MCS;
+		rate->flags = RATE_INFO_FLAGS_HE_MCS;
 		break;
 	default:
-		break;
+		return -EINVAL;
 	}
-	rate->flags = flags;
 
 	if (ru_idx) {
 		switch (ru_idx) {
@@ -448,6 +456,8 @@ mt7915_mcu_tx_rate_parse(struct mt76_phy *mphy, struct mt7915_mcu_ra_info *ra,
 			break;
 		}
 	}
+
+	return 0;
 }
 
 static void
@@ -478,12 +488,12 @@ mt7915_mcu_tx_rate_report(struct mt7915_dev *dev, struct sk_buff *skb)
 		mphy = dev->mt76.phy2;
 
 	/* current rate */
-	mt7915_mcu_tx_rate_parse(mphy, ra, &rate, curr);
-	stats->tx_rate = rate;
+	if (!mt7915_mcu_tx_rate_parse(mphy, ra, &rate, curr))
+		stats->tx_rate = rate;
 
 	/* probing rate */
-	mt7915_mcu_tx_rate_parse(mphy, ra, &prob_rate, probe);
-	stats->prob_rate = prob_rate;
+	if (!mt7915_mcu_tx_rate_parse(mphy, ra, &prob_rate, probe))
+		stats->prob_rate = prob_rate;
 
 	if (attempts) {
 		u16 success = le16_to_cpu(ra->success);