Commit f5990207 authored Jun 20, 2025 by Breno Leitao Committed by Jakub Kicinski Jun 23, 2025

net: netpoll: Initialize UDP checksum field before checksumming



commit f1fce08e ("netpoll: Eliminate redundant assignment") removed
the initialization of the UDP checksum, which was wrong and broke
netpoll IPv6 transmission due to bad checksumming.

udph->check needs to be set before calling csum_ipv6_magic().

Fixes: f1fce08e ("netpoll: Eliminate redundant assignment")
Signed-off-by: Breno Leitao <leitao@debian.org>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://patch.msgid.link/20250620-netpoll_fix-v1-1-f9f0b82bc059@debian.org


Signed-off-by: Jakub Kicinski <kuba@kernel.org>

parent 95b6759a

net/core/netpoll.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -432,6 +432,7 @@ int netpoll_send_udp(struct netpoll np, const char msg, int len)
		udph->dest = htons(np->remote_port);
		udph->len = htons(udp_len);

		udph->check = 0;
		if (np->ipv6) {
		udph->check = csum_ipv6_magic(&np->local_ip.in6,
		&np->remote_ip.in6,
		@@ -460,7 +461,6 @@ int netpoll_send_udp(struct netpoll np, const char msg, int len)
		skb_reset_mac_header(skb);
		skb->protocol = eth->h_proto = htons(ETH_P_IPV6);
		} else {
		udph->check = 0;
		udph->check = csum_tcpudp_magic(np->local_ip.ip,
		np->remote_ip.ip,
		udp_len, IPPROTO_UDP,