On Tue, Jan 05, 2021 at 04:05:21PM -0800, David Miller wrote:
From: Tong Zhu zhutong@amazon.com 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@amazon.com
Please repost with an appropriate Fixes: tag.
Thanks.
I had a second thought on this. This fix should go mainline too. This is a case we are sending out queued packets when arp reply from the neighbour comes in. With 5.x kernel, a dst in DST_OBSOLETE_DEAD state leads to dropping of this packet. It is not as bad as with 4.x kernel that may end up with an all-zero mac address packet out to ethernet or choking up ath9k when using block ack. Dropping the packet is still wrong. I’ll repost as a fix to mainline and target backport to 4.x LTS releases.
Best regards