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Commit b4e98937 authored Oct 22, 2023 by Pablo Neira Ayuso Committed by Greg Kroah-Hartman Nov 08, 2023

gtp: fix fragmentation needed check with gso

commit 4530e5b8e2dad63dcad2206232dd86e4b1489b6c upstream.

Call skb_gso_validate_network_len() to check if packet is over PMTU.

Fixes: 459aa660 ("gtp: add initial driver for datapath of GPRS Tunneling Protocol (GTP-U)")
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent f7c34618

drivers/net/gtp.c

+3 −2

Original line number	Diff line number	Diff line
		@@ -548,8 +548,9 @@ static int gtp_build_skb_ip4(struct sk_buff skb, struct net_device dev,

		rt->dst.ops->update_pmtu(&rt->dst, NULL, skb, mtu, false);

		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));