Re: [PATCH] neighbour: Disregard DEAD dst in neigh_update

[David Miller]

From: Tong Zhu <zhutong@xxxxxxxxxx>
Date: Wed, 30 Dec 2020 17:54:23 -0500

> In 4.x kernel a dst in DST_OBSOLETE_DEAD state is associated
> with loopback net_device and leads to loopback neighbour. It
> leads to an ethernet header with all zero addresses.
> 
> A very troubling case is working with mac80211 and ath9k.
> A packet with all zero source MAC address to mac80211 will
> eventually fail ieee80211_find_sta_by_ifaddr in ath9k (xmit.c).
> As result, ath9k flushes tx queue (ath_tx_complete_aggr) without
> updating baw (block ack window), damages baw logic and disables
> transmission.
> 
> Signed-off-by: Tong Zhu <zhutong@xxxxxxxxxx>

Please repost with an appropriate Fixes: tag.

Thanks.