[PATCH] wifi: mt76: mt7925: add NULL checks and error handling for MCU calls

[Zac Bowling <zbowling@gmail.com>]

From: Zac Bowling <zac@zacbowling.com>

Add NULL pointer checks for mt792x_sta_to_link() and mt792x_vif_to_link()
results in critical paths to prevent kernel crashes during MLO operations.

Add error logging for MCU return values in mt7925_regd_update() to help
diagnose regulatory domain update failures.

Found by static analysis review.
---
 drivers/net/wireless/mediatek/mt76/mt7925/init.c | 13 ++++++++++---
 drivers/net/wireless/mediatek/mt76/mt7925/main.c |  8 ++++++++
 2 files changed, 18 insertions(+), 3 deletions(-)

diff --git a/drivers/net/wireless/mediatek/mt76/mt7925/init.c b/drivers/net/wireless/mediatek/mt76/mt7925/init.c
index d7d5afe365ed..f800112ccaf7 100644
--- a/drivers/net/wireless/mediatek/mt76/mt7925/init.c
+++ b/drivers/net/wireless/mediatek/mt76/mt7925/init.c
@@ -162,10 +162,17 @@ void mt7925_regd_update(struct mt792x_dev *dev)
 	if (!dev->regd_change)
 		return;
 
-	mt7925_mcu_set_clc(dev, mdev->alpha2, dev->country_ie_env);
+	if (mt7925_mcu_set_clc(dev, mdev->alpha2, dev->country_ie_env) < 0)
+		dev_warn(dev->mt76.dev, "Failed to set CLC\n");
+
 	mt7925_regd_channel_update(wiphy, dev);
-	mt7925_mcu_set_channel_domain(hw->priv);
-	mt7925_set_tx_sar_pwr(hw, NULL);
+
+	if (mt7925_mcu_set_channel_domain(hw->priv) < 0)
+		dev_warn(dev->mt76.dev, "Failed to set channel domain\n");
+
+	if (mt7925_set_tx_sar_pwr(hw, NULL) < 0)
+		dev_warn(dev->mt76.dev, "Failed to set TX SAR power\n");
+
 	dev->regd_change = false;
 }
 EXPORT_SYMBOL_GPL(mt7925_regd_update);
diff --git a/drivers/net/wireless/mediatek/mt76/mt7925/main.c b/drivers/net/wireless/mediatek/mt76/mt7925/main.c
index 11c0197c7426..b6e3002faf41 100644
--- a/drivers/net/wireless/mediatek/mt76/mt7925/main.c
+++ b/drivers/net/wireless/mediatek/mt76/mt7925/main.c
@@ -863,12 +863,17 @@ static int mt7925_mac_link_sta_add(struct mt76_dev *mdev,
 
 	msta = (struct mt792x_sta *)link_sta->sta->drv_priv;
 	mlink = mt792x_sta_to_link(msta, link_id);
+	if (!mlink)
+		return -EINVAL;
 
 	idx = mt76_wcid_alloc(dev->mt76.wcid_mask, MT792x_WTBL_STA - 1);
 	if (idx < 0)
 		return -ENOSPC;
 
 	mconf = mt792x_vif_to_link(mvif, link_id);
+	if (!mconf)
+		return -EINVAL;
+
 	mt76_wcid_init(&mlink->wcid, 0);
 	mlink->wcid.sta = 1;
 	mlink->wcid.idx = idx;
@@ -1750,6 +1755,9 @@ mt7925_conf_tx(struct ieee80211_hw *hw, struct ieee80211_vif *vif,
 		    [IEEE80211_AC_BK] = 1,
 	};
 
+	if (!mconf)
+		return -EINVAL;
+
 	/* firmware uses access class index */
 	mconf->queue_params[mq_to_aci[queue]] = *params;
 
-- 
2.51.0