Commit 143a8526 authored by Guillaume Nault's avatar Guillaume Nault Committed by Jakub Kicinski
Browse files

bareudp: Fix invalid read beyond skb's linear data 



Data beyond the UDP header might not be part of the skb's linear data.
Use skb_copy_bits() instead of direct access to skb->data+X, so that
we read the correct bytes even on a fragmented skb.

Fixes: 4b5f6723 ("net: Special handling for IP & MPLS.")
Signed-off-by: default avatarGuillaume Nault <gnault@redhat.com>
Link: https://lore.kernel.org/r/7741c46545c6ef02e70c80a9b32814b22d9616b3.1628264975.git.gnault@redhat.com


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent d6e712aa

drivers/net/bareudp.c

+11 −5
Original line number Diff line number Diff line
@@ -71,12 +71,18 @@ static int bareudp_udp_encap_recv(struct sock *sk, struct sk_buff *skb) 
		family = AF_INET6;



	if (bareudp->ethertype == htons(ETH_P_IP)) {

		struct iphdr *iphdr;

		__u8 ipversion;



		iphdr = (struct iphdr *)(skb->data + BAREUDP_BASE_HLEN);

		if (iphdr->version == 4) {

			proto = bareudp->ethertype;

		} else if (bareudp->multi_proto_mode && (iphdr->version == 6)) {

		if (skb_copy_bits(skb, BAREUDP_BASE_HLEN, &ipversion,

				  sizeof(ipversion))) {

			bareudp->dev->stats.rx_dropped++;

			goto drop;

		}

		ipversion >>= 4;



		if (ipversion == 4) {

			proto = htons(ETH_P_IP);

		} else if (ipversion == 6 && bareudp->multi_proto_mode) {

			proto = htons(ETH_P_IPV6);

		} else {

			bareudp->dev->stats.rx_dropped++;