On transmit, we are currently relying on skb->dev being set by mctp_local_output() when we first set up the skb destination fields. However, forwarded skbs do not use the local_output path, so will retain their incoming netdev as their ->dev on tx. This does not work when we're forwarding between interfaces. Set skb->dev unconditionally in the transmit path, to allow for proper forwarding. We keep the skb->dev initialisation in mctp_local_output(), as we use it for fragmentation. Fixes: 269936db5eb3 ("net: mctp: separate routing database from routing operations") Suggested-by: Vince Chang Signed-off-by: Jeremy Kerr --- net/mctp/route.c | 1 + 1 file changed, 1 insertion(+) diff --git a/net/mctp/route.c b/net/mctp/route.c index 4d314e062ba9c4137f196482880660be67a71b11..2ac4011a953fffe9e01f3bfe0f571b3727b3e903 100644 --- a/net/mctp/route.c +++ b/net/mctp/route.c @@ -623,6 +623,7 @@ static int mctp_dst_output(struct mctp_dst *dst, struct sk_buff *skb) skb->protocol = htons(ETH_P_MCTP); skb->pkt_type = PACKET_OUTGOING; + skb->dev = dst->dev->dev; if (skb->len > dst->mtu) { kfree_skb(skb); --- base-commit: 4c19c4fa8dabb945a017c1910605ab2616725c6c change-id: 20251125-dev-forward-932c006dec72 Best regards, -- Jeremy Kerr