diff options
| author | Tong Zhu <zhutong@amazon.com> | 2021-03-19 14:33:37 -0400 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2021-03-31 14:10:46 -0700 |
| commit | d47ec7a0a7271dda08932d6208e4ab65ab0c987c (patch) | |
| tree | 77f87ea9b8f9e7ab159cbebb9633f9e22816a90d /net | |
| parent | 61431a5907fc36d0738e9a547c7e1556349a03e9 (diff) | |
neighbour: Disregard DEAD dst in neigh_update
After a short network outage, the dst_entry is timed out and put
in DST_OBSOLETE_DEAD. We are in this code because arp reply comes
from this neighbour after network recovers. There is a potential
race condition that dst_entry is still in DST_OBSOLETE_DEAD.
With that, another neighbour lookup causes more harm than good.
In best case all packets in arp_queue are lost. This is
counterproductive to the original goal of finding a better path
for those packets.
I observed a worst case with 4.x kernel where a dst_entry in
DST_OBSOLETE_DEAD state is associated with loopback net_device.
It leads to an ethernet header with all zero addresses.
A packet with all zero source MAC address is quite deadly with
mac80211, ath9k and 802.11 block ack. It fails
ieee80211_find_sta_by_ifaddr in ath9k (xmit.c). Ath9k flushes tx
queue (ath_tx_complete_aggr). BAW (block ack window) is not
updated. BAW logic is damaged and ath9k transmission is disabled.
Signed-off-by: Tong Zhu <zhutong@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net')
| -rw-r--r-- | net/core/neighbour.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/net/core/neighbour.c b/net/core/neighbour.c index e2982b3970b8..8379719d1dce 100644 --- a/net/core/neighbour.c +++ b/net/core/neighbour.c @@ -1379,7 +1379,7 @@ static int __neigh_update(struct neighbour *neigh, const u8 *lladdr, * we can reinject the packet there. */ n2 = NULL; - if (dst) { + if (dst && dst->obsolete != DST_OBSOLETE_DEAD) { n2 = dst_neigh_lookup_skb(dst, skb); if (n2) n1 = n2; |