Hi, Neigh ha address must be read using the seqlock to get a stable snapshot. Both the bridge and vxlan read it directly and can see partial updates. I reproduced both issues with running neigh updates and exercising these paths in parallel and saw partial addresses, e.g. updating between neigh A: 02:00:00:00:00:00 neigh B: fe:ff:ff:ff:ff:ff was able to observe 02:00:ff:ff:ff:ff and fe:ff:00:00:00:00 in packets. Noticed this initially in the bridge, then checked vxlan and its arp/neigh_reduce functions have the same bug, route_shortcircuit is doing the right thing already.
v1 link: https://lore.kernel.org/netdev/[email protected]/ v2: - use ETH_ALEN instead of MAX_ADDR_LEN, the bridge devices all use ETH_ALEN and vxlan allows arp/nd reduce only when not in raw/gpe so it also always uses ETH_ALEN - align ha to 2 bytes because ether_addr_copy() expects it (Sashiko) 2-byte alignment is not strictly necessary everywhere (e.g. the ARP suppress side can't reach ether_addr_copy) but it doesn't cost us anything and is aligned with the rest of the code. Cheers, Nik Nikolay Aleksandrov (2): net: bridge: arp/nd proxy: fix reading neigh ha vxlan: fix reading neigh ha drivers/net/vxlan/vxlan_core.c | 20 +++++++++++++------- net/bridge/br_arp_nd_proxy.c | 24 ++++++++++++++---------- 2 files changed, 27 insertions(+), 17 deletions(-) -- 2.47.3
