From 491d786c1b810f841f76fc01d0f991e64ff973c3 Mon Sep 17 00:00:00 2001 From: Eason Lai Date: Wed, 1 Jul 2026 09:06:54 +0800 Subject: [PATCH] wifi: mt76: mt792x: fix use-after-free in mt76_rx_poll_complete A use-after-free issue occurs in mt76_rx_poll_complete due to a race condition. The STA has already been removed, but the rx_status still had a pointer to the wcid in the STA. Set the links' wcid pointers to be NULL for a MLD in mt7925_sta_pre_rcu_remove() BUG: KASAN: invalid-access in mt76_rx_poll_complete+0x280/0x470 Call trace: dump_backtrace+0xec/0x128 show_stack+0x18/0x28 dump_stack_lvl+0x40/0xc8 print_report+0x1b8/0x710 kasan_report+0xe0/0x144 do_bad_area+0x120/0x260 do_tag_check_fault+0x20/0x34 do_mem_abort+0x54/0xa8 el1_abort+0x3c/0x5c el1h_64_sync_handler+0x40/0xcc el1h_64_sync+0x7c/0x80 mt76_rx_poll_complete+0x280/0x470 mt76_dma_rx_poll+0x114/0x51c mt792x_poll_rx+0x60/0xf8 napi_threaded_poll_loop+0xe0/0x450 napi_threaded_poll+0x80/0x9c kthread+0x11c/0x158 ret_from_fork+0x10/0x20 Fixes: c948b5da6bbe ("wifi: mt76: mt7925: add Mediatek Wi-Fi7 driver for mt7925 chips") Signed-off-by: Eason Lai Link: https://patch.msgid.link/20260701010654.956863-1-eason.lai@mediatek.com Signed-off-by: Felix Fietkau --- mt7925/main.c | 36 +++++++++++++++++++++++++++++++++++- 1 file changed, 35 insertions(+), 1 deletion(-) diff --git a/mt7925/main.c b/mt7925/main.c index 2b6cc8e2..3ee455d2 100644 --- a/mt7925/main.c +++ b/mt7925/main.c @@ -2484,6 +2484,40 @@ static void mt7925_channel_switch_rx_beacon(struct ieee80211_hw *hw, } } +static void mt7925_sta_pre_rcu_remove(struct ieee80211_hw *hw, + struct ieee80211_vif *vif, + struct ieee80211_sta *sta) +{ + struct mt76_phy *phy = hw->priv; + struct mt76_dev *dev = phy->dev; + struct mt76_wcid *wcid = (struct mt76_wcid *)sta->drv_priv; + + mutex_lock(&dev->mutex); + spin_lock_bh(&dev->status_lock); + + if (ieee80211_vif_is_mld(vif)) { + struct mt792x_sta *msta = (struct mt792x_sta *)sta->drv_priv; + struct mt792x_vif *mvif = (struct mt792x_vif *)vif->drv_priv; + unsigned long valid = mvif->valid_links; + struct mt792x_link_sta *mlink; + unsigned int link_id; + + for_each_set_bit(link_id, &valid, IEEE80211_MLD_MAX_NUM_LINKS) { + mlink = mt792x_sta_to_link(msta, link_id); + if (!mlink || !mlink->wcid.sta) + continue; + if (mlink->wcid.idx < ARRAY_SIZE(dev->wcid)) + rcu_assign_pointer(dev->wcid[mlink->wcid.idx], + NULL); + } + } else { + rcu_assign_pointer(dev->wcid[wcid->idx], NULL); + } + + spin_unlock_bh(&dev->status_lock); + mutex_unlock(&dev->mutex); +} + const struct ieee80211_ops mt7925_ops = { .tx = mt792x_tx, .start = mt7925_start, @@ -2496,7 +2530,7 @@ const struct ieee80211_ops mt7925_ops = { .start_ap = mt7925_start_ap, .stop_ap = mt7925_stop_ap, .sta_state = mt76_sta_state, - .sta_pre_rcu_remove = mt76_sta_pre_rcu_remove, + .sta_pre_rcu_remove = mt7925_sta_pre_rcu_remove, .set_key = mt7925_set_key, .sta_set_decap_offload = mt7925_sta_set_decap_offload, #if IS_ENABLED(CONFIG_IPV6)