Commit 6d39d589 authored by Florian Westphal's avatar Florian Westphal Committed by David S. Miller
Browse files

net: core: don't account for udp header size when computing seglen

In case of tcp, gso_size contains the tcpmss.

For UFO (udp fragmentation offloading) skbs, gso_size is the fragment
payload size, i.e. we must not account for udp header size.

Otherwise, when using virtio drivers, a to-be-forwarded UFO GSO packet
will be needlessly fragmented in the forward path, because we think its
individual segments are too large for the outgoing link.

Fixes: fe6cc55f

 ("net: ip, ipv6: handle gso skbs in forwarding path")
Cc: Eric Dumazet <>
Reported-by: default avatarTobias Brunner <>
Signed-off-by: default avatarFlorian Westphal <>
Signed-off-by: default avatarDavid S. Miller <>
parent f34c4a35
......@@ -3937,12 +3937,14 @@ EXPORT_SYMBOL_GPL(skb_scrub_packet);
unsigned int skb_gso_transport_seglen(const struct sk_buff *skb)
const struct skb_shared_info *shinfo = skb_shinfo(skb);
unsigned int hdr_len;
if (likely(shinfo->gso_type & (SKB_GSO_TCPV4 | SKB_GSO_TCPV6)))
hdr_len = tcp_hdrlen(skb);
hdr_len = sizeof(struct udphdr);
return hdr_len + shinfo->gso_size;
return tcp_hdrlen(skb) + shinfo->gso_size;
/* UFO sets gso_size to the size of the fragmentation
* payload, i.e. the size of the L4 (UDP) header is already
* accounted for.
return shinfo->gso_size;
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