udp: fix receiving fraglist GSO packets

[ Upstream commit b128ed5ab27330deeeaf51ea8bb69f1442a96f7f ]

When assembling fraglist GSO packets, udp4_gro_complete does not set
skb->csum_start, which makes the extra validation in __udp_gso_segment fail.

Fixes: 89add40066f9 ("net: drop bad gso csum_start and offset in virtio_net_hdr")
Signed-off-by: Felix Fietkau <nbd@nbd.name>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Link: https://patch.msgid.link/20240819150621.59833-1-nbd@nbd.name
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/net/ipv4/udp_offload.c b/net/ipv4/udp_offload.c
index ee9af921556a798625335512409939c798b0d55c..5b54f4f32b1cd8c9eadb46d919c06997f7cfc54e 100644 (file)
--- a/net/ipv4/udp_offload.c
+++ b/net/ipv4/udp_offload.c
@@ -279,7 +279,8 @@ struct sk_buff *__udp_gso_segment(struct sk_buff *gso_skb,
                return ERR_PTR(-EINVAL);
 
        if (unlikely(skb_checksum_start(gso_skb) !=
-                    skb_transport_header(gso_skb)))
+                    skb_transport_header(gso_skb) &&
+                    !(skb_shinfo(gso_skb)->gso_type & SKB_GSO_FRAGLIST)))
                return ERR_PTR(-EINVAL);
 
        if (skb_gso_ok(gso_skb, features | NETIF_F_GSO_ROBUST)) {