From: Felix Fietkau <nbd@nbd.name>
Date: Sat, 5 Jul 2025 13:44:10 +0200
Subject: [PATCH] net: fix TCP/UDP fraglist GRO

Since "net: gro: use cb instead of skb->network_header", the skb network
header is no longer set in the GRO path.
This breaks fraglist segmentation, which relies on ip_hdr()/tcp_hdr()
to check for address/port changes.
Fix this regression by selectively setting the network header for merged
segment skbs.

Fixes: 186b1ea73ad8 ("net: gro: use cb instead of skb->network_header")
Signed-off-by: Felix Fietkau <nbd@nbd.name>
---

--- a/net/ipv4/tcp_offload.c
+++ b/net/ipv4/tcp_offload.c
@@ -355,6 +355,7 @@ struct sk_buff *tcp_gro_receive(struct l
 		flush |= skb->ip_summed != p->ip_summed;
 		flush |= skb->csum_level != p->csum_level;
 		flush |= NAPI_GRO_CB(p)->count >= 64;
+		skb_set_network_header(skb, skb_gro_receive_network_offset(skb));
 
 		if (flush || skb_gro_receive_list(p, skb))
 			mss = 1;
--- a/net/ipv4/udp_offload.c
+++ b/net/ipv4/udp_offload.c
@@ -604,6 +604,7 @@ static struct sk_buff *udp_gro_receive_s
 					NAPI_GRO_CB(skb)->flush = 1;
 					return NULL;
 				}
+				skb_set_network_header(skb, skb_gro_receive_network_offset(skb));
 				ret = skb_gro_receive_list(p, skb);
 			} else {
 				skb_gro_postpull_rcsum(skb, uh,