This is a note to let you know that I've just added the patch titled

    net: fix segmentation of forwarding fraglist GRO

to the 6.6-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     net-fix-segmentation-of-forwarding-fraglist-gro.patch
and it can be found in the queue-6.6 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let [off-list ref] know about it.


From stable+bounces-222525-greg=kroah.com@vger.kernel.org Mon Mar  2 07:56:28 2026
From: Li hongliang <redacted>
Date: Mon,  2 Mar 2026 14:55:28 +0800
Subject: net: fix segmentation of forwarding fraglist GRO
To: gregkh@linuxfoundation.org, stable@vger.kernel.org, jibin.zhang@mediatek.com
Cc: patches@lists.linux.dev, linux-kernel@vger.kernel.org, ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org, martin.lau@linux.dev, song@kernel.org, yhs@fb.com, john.fastabend@gmail.com, kpsingh@kernel.org, sdf@google.com, haoluo@google.com, jolsa@kernel.org, davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, yoshfuji@linux-ipv6.org, dsahern@kernel.org, matthias.bgg@gmail.com, willemb@google.com, steffen.klassert@secunet.com, bpf@vger.kernel.org, netdev@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-mediatek@lists.infradead.org
Message-ID: [ref]

From: Jibin Zhang <redacted>

[ Upstream commit 426ca15c7f6cb6562a081341ca88893a50c59fa2 ]

This patch enhances GSO segment handling by properly checking
the SKB_GSO_DODGY flag for frag_list GSO packets, addressing
low throughput issues observed when a station accesses IPv4
servers via hotspots with an IPv6-only upstream interface.

Specifically, it fixes a bug in GSO segmentation when forwarding
GRO packets containing a frag_list. The function skb_segment_list
cannot correctly process GRO skbs that have been converted by XLAT,
since XLAT only translates the header of the head skb. Consequently,
skbs in the frag_list may remain untranslated, resulting in protocol
inconsistencies and reduced throughput.

To address this, the patch explicitly sets the SKB_GSO_DODGY flag
for GSO packets in XLAT's IPv4/IPv6 protocol translation helpers
(bpf_skb_proto_4_to_6 and bpf_skb_proto_6_to_4). This marks GSO
packets as potentially modified after protocol translation. As a
result, GSO segmentation will avoid using skb_segment_list and
instead falls back to skb_segment for packets with the SKB_GSO_DODGY
flag. This ensures that only safe and fully translated frag_list
packets are processed by skb_segment_list, resolving protocol
inconsistencies and improving throughput when forwarding GRO packets
converted by XLAT.

Signed-off-by: Jibin Zhang <redacted>
Fixes: 9fd1ff5d2ac7 ("udp: Support UDP fraglist GRO/GSO.")
Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260126152114.1211-1-jibin.zhang@mediatek.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Li hongliang <redacted>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 net/core/filter.c        |    2 ++
 net/ipv4/tcp_offload.c   |    3 ++-
 net/ipv4/udp_offload.c   |    3 ++-
 net/ipv6/tcpv6_offload.c |    3 ++-
 4 files changed, 8 insertions(+), 3 deletions(-)

--- a/net/core/filter.c
+++ b/net/core/filter.c

@@ -3340,6 +3340,7 @@ static int bpf_skb_proto_4_to_6(struct s
 			shinfo->gso_type &= ~SKB_GSO_TCPV4;
 			shinfo->gso_type |=  SKB_GSO_TCPV6;
 		}
+		shinfo->gso_type |=  SKB_GSO_DODGY;
 	}
 
 	bpf_skb_change_protocol(skb, ETH_P_IPV6);

@@ -3370,6 +3371,7 @@ static int bpf_skb_proto_6_to_4(struct s
 			shinfo->gso_type &= ~SKB_GSO_TCPV6;
 			shinfo->gso_type |=  SKB_GSO_TCPV4;
 		}
+		shinfo->gso_type |=  SKB_GSO_DODGY;
 	}
 
 	bpf_skb_change_protocol(skb, ETH_P_IP);
--- a/net/ipv4/tcp_offload.c
+++ b/net/ipv4/tcp_offload.c

@@ -107,7 +107,8 @@ static struct sk_buff *tcp4_gso_segment(
 	if (skb_shinfo(skb)->gso_type & SKB_GSO_FRAGLIST) {
 		struct tcphdr *th = tcp_hdr(skb);
 
-		if (skb_pagelen(skb) - th->doff * 4 == skb_shinfo(skb)->gso_size)
+		if ((skb_pagelen(skb) - th->doff * 4 == skb_shinfo(skb)->gso_size) &&
+		    !(skb_shinfo(skb)->gso_type & SKB_GSO_DODGY))
 			return __tcp4_gso_segment_list(skb, features);
 
 		skb->ip_summed = CHECKSUM_NONE;
--- a/net/ipv4/udp_offload.c
+++ b/net/ipv4/udp_offload.c

@@ -352,7 +352,8 @@ struct sk_buff *__udp_gso_segment(struct
 
 	if (skb_shinfo(gso_skb)->gso_type & SKB_GSO_FRAGLIST) {
 		 /* Detect modified geometry and pass those to skb_segment. */
-		if (skb_pagelen(gso_skb) - sizeof(*uh) == skb_shinfo(gso_skb)->gso_size)
+		if ((skb_pagelen(gso_skb) - sizeof(*uh) == skb_shinfo(gso_skb)->gso_size) &&
+		    !(skb_shinfo(gso_skb)->gso_type & SKB_GSO_DODGY))
 			return __udp_gso_segment_list(gso_skb, features, is_ipv6);
 
 		ret = __skb_linearize(gso_skb);
--- a/net/ipv6/tcpv6_offload.c
+++ b/net/ipv6/tcpv6_offload.c

@@ -109,7 +109,8 @@ static struct sk_buff *tcp6_gso_segment(
 	if (skb_shinfo(skb)->gso_type & SKB_GSO_FRAGLIST) {
 		struct tcphdr *th = tcp_hdr(skb);
 
-		if (skb_pagelen(skb) - th->doff * 4 == skb_shinfo(skb)->gso_size)
+		if ((skb_pagelen(skb) - th->doff * 4 == skb_shinfo(skb)->gso_size) &&
+		    !(skb_shinfo(skb)->gso_type & SKB_GSO_DODGY))
 			return __tcp6_gso_segment_list(skb, features);
 
 		skb->ip_summed = CHECKSUM_NONE;

Patches currently in stable-queue which might be from 1468888505@139.com are

queue-6.6/pnfs-fix-a-deadlock-when-returning-a-delegation-during-open.patch
queue-6.6/net-add-support-for-segmenting-tcp-fraglist-gso-packets.patch
queue-6.6/net-fix-segmentation-of-forwarding-fraglist-gro.patch
queue-6.6/nfs-pass-explicit-offset-count-to-trace-events.patch
queue-6.6/net-gso-fix-tcp-fraglist-segmentation-after-pull-from-frag_list.patch
queue-6.6/nfs-fix-a-deadlock-involving-nfs_release_folio.patch