From 4330a0ef9f75a54fde3548432a9a698f06bab635 Mon Sep 17 00:00:00 2001 From: Felix Fietkau Date: Sat, 1 Aug 2026 14:53:34 +0000 Subject: [PATCH] wifi: mt76: mt7996: fix out-of-bounds link array access in mt7996_tx() When mac80211 leaves the link unspecified, mt7996_tx() substitutes the primary link id of the station or vif. That value is IEEE80211_LINK_UNSPECIFIED (0xf) until the first link has been added, and it is then used unchecked to index vif->link_conf[], mvif->mt76.link[] and sta->link[], all of which hold IEEE80211_MLD_MAX_NUM_LINKS (15) entries. Clamp the primary link id to the default link before using it, and use the clamped value for the link_sta fallback as well. Fixes: 1609b014aa29 ("wifi: mt76: mt7996: Overwrite unspecified link_id in mt7996_tx()") Link: https://patch.msgid.link/20260801145334.1166751-10-nbd@nbd.name Signed-off-by: Felix Fietkau --- .../net/wireless/mediatek/mt76/mt7996/main.c | 20 ++++++++++++------- 1 file changed, 13 insertions(+), 7 deletions(-) diff --git a/drivers/net/wireless/mediatek/mt76/mt7996/main.c b/drivers/net/wireless/mediatek/mt76/mt7996/main.c index 54e79bd25995..e218856b0c45 100644 --- a/drivers/net/wireless/mediatek/mt76/mt7996/main.c +++ b/drivers/net/wireless/mediatek/mt76/mt7996/main.c @@ -1515,20 +1515,26 @@ static void mt7996_tx(struct ieee80211_hw *hw, struct ieee80211_vif *vif = info->control.vif; struct mt7996_vif *mvif = vif ? (void *)vif->drv_priv : NULL; struct mt76_wcid *wcid = &dev->mt76.global_wcid; + u8 deflink_id = IEEE80211_LINK_UNSPECIFIED; u8 link_id = u32_get_bits(info->control.flags, IEEE80211_TX_CTRL_MLO_LINK); rcu_read_lock(); + if (msta) + deflink_id = msta->deflink_id; + else if (mvif) + deflink_id = mvif->mt76.deflink_id; + + /* the primary link is unset until the first link has been added */ + if (deflink_id >= IEEE80211_MLD_MAX_NUM_LINKS) + deflink_id = 0; + /* Use primary link_id if the value from mac80211 is set to * IEEE80211_LINK_UNSPECIFIED. */ - if (link_id == IEEE80211_LINK_UNSPECIFIED) { - if (msta) - link_id = msta->deflink_id; - else if (mvif) - link_id = mvif->mt76.deflink_id; - } + if (link_id == IEEE80211_LINK_UNSPECIFIED) + link_id = deflink_id; if (vif && ieee80211_vif_is_mld(vif)) { struct ieee80211_bss_conf *link_conf; @@ -1538,7 +1544,7 @@ static void mt7996_tx(struct ieee80211_hw *hw, link_sta = rcu_dereference(sta->link[link_id]); if (!link_sta) - link_sta = rcu_dereference(sta->link[msta->deflink_id]); + link_sta = rcu_dereference(sta->link[deflink_id]); if (link_sta) { memcpy(hdr->addr1, link_sta->addr, ETH_ALEN);