[PATCH net 2/2] gtp: fix fragmentation needed check with gso

Call skb_gso_validate_network_len() to check if packet is over PMTU. Fixes: 459aa660eb1d ("gtp: add initial driver for datapath of GPRS Tunneling Protocol (GTP-U)") Signed-off-by: Pablo Neira Ayuso &lt;pablo(a)netfilter.org&gt; --- drivers/net/gtp.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/drivers/net/gtp.c b/drivers/net/gtp.c index 144ec626230d..b22596b18ee8 100644 --- a/drivers/net/gtp.c +++ b/drivers/net/gtp.c @@ -872,8 +872,9 @@ static int gtp_build_skb_ip4(struct sk_buff *skb, struct net_device *dev, skb_dst_update_pmtu_no_confirm(skb, mtu); - if (!skb_is_gso(skb) && (iph->frag_off & htons(IP_DF)) && - mtu < ntohs(iph->tot_len)) { + if (iph->frag_off & htons(IP_DF) && + ((!skb_is_gso(skb) && skb->len > mtu) || + (skb_is_gso(skb) && !skb_gso_validate_network_len(skb, mtu)))) { netdev_dbg(dev, "packet too big, fragmentation needed\n"); icmp_ndo_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED, htonl(mtu)); -- 2.30.2