High [CVE-2026-64175] stop TX during firmware restart
This high-severity Red Hat Linux advisory covers CVE-2026-64175 affecting Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 9, Red Hat package: kernel-rt.
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Summary
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.
Affected versions
No affected-version range was extracted from the source record. The vendor advisory is authoritative — check it before change work.
Official advisory · high-confidence parse· fetched 6 days ago·verify at source
Fixed versions
No fixed release is recorded yet. That does not prove no patch exists — confirm against the vendor advisory.
Official advisory · high-confidence parse· fetched 6 days ago·verify at source
Mitigation checklist
- To mitigate this issue, the `iwlwifi` kernel module can be blacklisted to prevent it from loading. This will disable Wi-Fi functionality on the system. To blacklist the module: 1. Create a file `/etc/modprobe.d/blacklist-iwlwifi.conf` with the following content: ``` blacklist iwlwifi ``` 2. Regenerate the initramfs: ```bash sudo dracut -f -v ``` or ```bash sudo mkinitrd -f -v /boot/initramfs-$(uname -r).img $(uname -r) ``` 3. Reboot the system for the changes to take effect. Note that disabling the `iwlwifi` module will prevent the use of Intel Wi-Fi devices.
Official advisory · high-confidence parse· fetched 6 days ago·verify at source
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