[PATCH net 3/5] vxlan: use neigh_ha_snapshot() in route_shortcircuit()
From: Eric Dumazet <edumazet@google.com>
Date: 2026-07-23 14:42:58
Also in:
stable
Subsystem:
networking drivers, the rest · Maintainers:
Andrew Lunn, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
The neighbour hardware address n->ha can be updated asynchronously by the
neighbour subsystem, protected by n->ha_lock seqlock. Reading n->ha without
holding the seqlock loop can lead to torn reads or reading a partially updated
MAC address.
Use neigh_ha_snapshot() in route_shortcircuit() to safely copy n->ha under
read_seqbegin()/read_seqretry() lock protection before using it.
Note that arp_reduce() and neigh_reduce() seem to have the same issue
left for future patches.
Fixes: e4f67addf158 ("add DOVE extensions for VXLAN")
Cc: stable@vger.kernel.org
Signed-off-by: Eric Dumazet <edumazet@google.com>
---
drivers/net/vxlan/vxlan_core.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/drivers/net/vxlan/vxlan_core.c b/drivers/net/vxlan/vxlan_core.c
index fb4a706cd5786d1937b1922acced31ffdb187c2f..10dd19eec09e266197ee51330a652f4e76c9643a 100644
--- a/drivers/net/vxlan/vxlan_core.c
+++ b/drivers/net/vxlan/vxlan_core.c@@ -2159,9 +2159,11 @@ static bool route_shortcircuit(struct net_device *dev, struct sk_buff *skb) } if (n) { + u8 haddr[ETH_ALEN]; bool diff; - diff = !ether_addr_equal(eth_hdr(skb)->h_dest, n->ha); + neigh_ha_snapshot(haddr, n, dev); + diff = !ether_addr_equal_unaligned(eth_hdr(skb)->h_dest, haddr); if (diff) { if (skb_cow_head(skb, 0)) { neigh_release(n);
@@ -2169,7 +2171,7 @@ static bool route_shortcircuit(struct net_device *dev, struct sk_buff *skb) } memcpy(eth_hdr(skb)->h_source, eth_hdr(skb)->h_dest, dev->addr_len); - memcpy(eth_hdr(skb)->h_dest, n->ha, dev->addr_len); + memcpy(eth_hdr(skb)->h_dest, haddr, dev->addr_len); } neigh_release(n); return diff;
--
2.55.0.229.g6434b31f56-goog