wifi: mt76: mt7996: fix null pointer deref in mt7996_conf_tx()

BugLink: https://bugs.launchpad.net/bugs/2139960

[ Upstream commit 79277f8 ]

If a link does not have an assigned channel yet, mt7996_vif_link returns
NULL. We still need to store the updated queue settings in that case, and
apply them later.
Move the location of the queue params to within struct mt7996_vif_link.

Fixes: c0df2f0 ("wifi: mt76: mt7996: prepare mt7996_mcu_set_tx for MLO support")
Acked-by: Lorenzo Bianconi <lorenzo@kernel.org>
Link: https://patch.msgid.link/20250929111723.52486-1-nbd@nbd.name
Signed-off-by: Felix Fietkau <nbd@nbd.name>
Signed-off-by: Sasha Levin <sashal@kernel.org>
CVE-2025-68738
Signed-off-by: Manuel Diewald <manuel.diewald@canonical.com>
Signed-off-by: Edoardo Canepa <edoardo.canepa@canonical.com>

Author: nbd168

drivers/net/wireless/mediatek/mt76/mt7996/main.c

@@ -650,8 +650,8 @@ mt7996_conf_tx(struct ieee80211_hw *hw, struct ieee80211_vif *vif,
 	       unsigned int link_id, u16 queue,
 	       const struct ieee80211_tx_queue_params *params)
 {
-	struct mt7996_dev *dev = mt7996_hw_dev(hw);
-	struct mt7996_vif_link *mlink = mt7996_vif_link(dev, vif, link_id);
+	struct mt7996_vif *mvif = (struct mt7996_vif *)vif->drv_priv;
+	struct mt7996_vif_link_info *link_info = &mvif->link_info[link_id];
 	static const u8 mq_to_aci[] = {
 		[IEEE80211_AC_VO] = 3,
 		[IEEE80211_AC_VI] = 2,
@@ -660,7 +660,7 @@ mt7996_conf_tx(struct ieee80211_hw *hw, struct ieee80211_vif *vif,
 	};
 
 	/* firmware uses access class index */
-	mlink->queue_params[mq_to_aci[queue]] = *params;
+	link_info->queue_params[mq_to_aci[queue]] = *params;
 	/* no need to update right away, we'll get BSS_CHANGED_QOS */
 
 	return 0;

drivers/net/wireless/mediatek/mt76/mt7996/mcu.c

@@ -3438,6 +3438,9 @@ int mt7996_mcu_set_tx(struct mt7996_dev *dev, struct ieee80211_vif *vif,
 #define WMM_PARAM_SET		(WMM_AIFS_SET | WMM_CW_MIN_SET | \
 				 WMM_CW_MAX_SET | WMM_TXOP_SET)
 	struct mt7996_vif_link *link = mt7996_vif_conf_link(dev, vif, link_conf);
+	struct mt7996_vif *mvif = (struct mt7996_vif *)vif->drv_priv;
+	unsigned int link_id = link_conf->link_id;
+	struct mt7996_vif_link_info *link_info = &mvif->link_info[link_id];
 	struct {
 		u8 bss_idx;
 		u8 __rsv[3];
@@ -3455,7 +3458,7 @@ int mt7996_mcu_set_tx(struct mt7996_dev *dev, struct ieee80211_vif *vif,
 	skb_put_data(skb, &hdr, sizeof(hdr));
 
 	for (ac = 0; ac < IEEE80211_NUM_ACS; ac++) {
-		struct ieee80211_tx_queue_params *q = &link->queue_params[ac];
+		struct ieee80211_tx_queue_params *q = &link_info->queue_params[ac];
 		struct edca *e;
 		struct tlv *tlv;
 

drivers/net/wireless/mediatek/mt76/mt7996/mt7996.h

@@ -246,16 +246,21 @@ struct mt7996_vif_link {
 	struct mt7996_sta_link msta_link;
 	struct mt7996_phy *phy;
 
-	struct ieee80211_tx_queue_params queue_params[IEEE80211_NUM_ACS];
 	struct cfg80211_bitrate_mask bitrate_mask;
 
 	u8 mld_idx;
 };
 
+struct mt7996_vif_link_info {
+	struct ieee80211_tx_queue_params queue_params[IEEE80211_NUM_ACS];
+};
+
 struct mt7996_vif {
 	struct mt7996_vif_link deflink; /* must be first */
 	struct mt76_vif_data mt76;
 
+	struct mt7996_vif_link_info link_info[IEEE80211_MLD_MAX_NUM_LINKS];
+
 	u8 mld_group_idx;
 	u8 mld_remap_idx;
 };