CVE-2026-64175

In the Linux kernel, the following vulnerability has been resolved:

wifi: iwlwifi: mld: stop TX during firmware restart

When iwlwifi firmware crashes (e.g., NMI_INTERRUPT_UNKNOWN on Intel

BE201/Wi-Fi 7), iwl_mld_nic_error() sets mld->fw_status.in_hw_restart

to true. However, iwl_mld_tx_from_txq() does not check this flag before

dequeuing frames from mac80211 and pushing them to the transport layer.

Since the firmware is dead, iwl_trans_tx() returns -EIO for each frame,

which then gets freed immediately. Under high-throughput conditions

(e.g., Tailscale UDP traffic or active SSH sessions), this creates a

tight dequeue-send-fail-free loop that wastes CPU cycles and generates

rapid skb allocation churn, leading to memory pressure from slab

fragmentation.

The RX path already has this guard (iwl_mld_rx_mpdu checks

in_hw_restart at rx.c:1906), and so does the TXQ allocation worker

(iwl_mld_add_txqs_wk at tx.c:156). Add the same guard to

iwl_mld_tx_from_txq() to stop all TX during firmware restart.

Frames left in mac80211's TXQs are naturally drained after restart

completes, when queue reallocation triggers iwl_mld_tx_from_txq()

via iwl_mld_add_txq_list(), or when new upper-layer traffic invokes

wake_tx_queue.

Tested on ASUS Zenbook 14 UX3405CA with Intel BE201 (Wi-Fi 7) on

kernel 6.19.5 where the firmware crashes approximately every 10-15

minutes under Tailscale traffic.