net: fix segmentation of forwarding fraglist GRO [ 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. BUG=b/484728118 TEST=presubmit RELEASE_NOTE=Fixed CVE-2026-23154 in the Linux kernel. cos-patch: security-moderate Change-Id: I47c44e4b7ec4175af884b37185a9bd4eb58da023 Signed-off-by: Jibin Zhang <jibin.zhang@mediatek.com> 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 <1468888505@139.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: chenglongtang <chenglongtang@google.com> Reviewed-on: https://cos-review.googlesource.com/c/third_party/kernel/+/143967 Tested-by: Cusky Presubmit Bot <presubmit@cos-infra-prod.iam.gserviceaccount.com> Reviewed-by: Kevin Berry <kpberry@google.com>
diff --git a/net/core/filter.c b/net/core/filter.c index f3098d8..faeefcc 100644 --- a/net/core/filter.c +++ b/net/core/filter.c
@@ -3342,6 +3342,7 @@ static int bpf_skb_proto_4_to_6(struct sk_buff *skb) 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); @@ -3372,6 +3373,7 @@ static int bpf_skb_proto_6_to_4(struct sk_buff *skb) 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);
diff --git a/net/ipv4/tcp_offload.c b/net/ipv4/tcp_offload.c index 3659570..7b09f6d 100644 --- a/net/ipv4/tcp_offload.c +++ b/net/ipv4/tcp_offload.c
@@ -107,7 +107,8 @@ static struct sk_buff *tcp4_gso_segment(struct sk_buff *skb, 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;
diff --git a/net/ipv4/udp_offload.c b/net/ipv4/udp_offload.c index 9be9df2..cd860d8 100644 --- a/net/ipv4/udp_offload.c +++ b/net/ipv4/udp_offload.c
@@ -352,7 +352,8 @@ struct sk_buff *__udp_gso_segment(struct sk_buff *gso_skb, 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);
diff --git a/net/ipv6/tcpv6_offload.c b/net/ipv6/tcpv6_offload.c index 7567c32..10025c9 100644 --- a/net/ipv6/tcpv6_offload.c +++ b/net/ipv6/tcpv6_offload.c
@@ -109,7 +109,8 @@ static struct sk_buff *tcp6_gso_segment(struct sk_buff *skb, 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;