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>
---
net/core/neighbour.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/net/core/neighbour.c b/net/core/neighbour.c
index 6e890f51b7d8..e471c32e448f 100644
--- a/net/core/neighbour.c
+++ b/net/core/neighbour.c
@@ -1271,7 +1271,7 @@ int neigh_update(struct neighbour *neigh, const u8 *lladdr, u8 new,
* 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;
--
2.17.1
