kernel: fix fraglist GRO on linux 6.12

Merged segments had a broken skb network header offset.

Fixes: https://github.com/openwrt/openwrt/issues/19130
Signed-off-by: Felix Fietkau <nbd@nbd.name>

diff --git a/target/linux/generic/pending-6.12/680-net-fix-TCP-UDP-fraglist-GRO.patch b/target/linux/generic/pending-6.12/680-net-fix-TCP-UDP-fraglist-GRO.patch
new file mode 100644 (file)
index 0000000..221e270
--- /dev/null
+++ b/target/linux/generic/pending-6.12/680-net-fix-TCP-UDP-fraglist-GRO.patch
@@ -0,0 +1,35 @@
+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,

diff --git a/target/linux/generic/pending-6.12/690-net-add-missing-check-for-TCP-fraglist-GRO.patch b/target/linux/generic/pending-6.12/690-net-add-missing-check-for-TCP-fraglist-GRO.patch
index b404037915dd3a18e21fb63b5402d938351ac3ff..2cf8cf159f6fb5b5e5c56ac18031036afbeafb58 100644 (file)
--- a/target/linux/generic/pending-6.12/690-net-add-missing-check-for-TCP-fraglist-GRO.patch
+++ b/target/linux/generic/pending-6.12/690-net-add-missing-check-for-TCP-fraglist-GRO.patch
@@ -22,5 +22,5 @@ Signed-off-by: Felix Fietkau <nbd@nbd.name>
                flush |= skb->csum_level != p->csum_level;
 +              flush |= !pskb_may_pull(skb, skb_gro_offset(skb));
                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))