Commit 8066e6b4 authored Jun 01, 2020 by Ido Schimmel Committed by David S. Miller Jun 01, 2020

vxlan: Avoid infinite loop when suppressing NS messages with invalid options

When proxy mode is enabled the vxlan device might reply to Neighbor
Solicitation (NS) messages on behalf of remote hosts.

In case the NS message includes the "Source link-layer address" option
[1], the vxlan device will use the specified address as the link-layer
destination address in its reply.

To avoid an infinite loop, break out of the options parsing loop when
encountering an option with length zero and disregard the NS message.

This is consistent with the IPv6 ndisc code and RFC 4886 which states
that "Nodes MUST silently discard an ND packet that contains an option
with length zero" [2].

[1] https://tools.ietf.org/html/rfc4861#section-4.3
[2] https://tools.ietf.org/html/rfc4861#section-4.6



Fixes: 4b29dba9 ("vxlan: fix nonfunctional neigh_reduce()")
Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Acked-by: Nikolay Aleksandrov <nikolay@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent 53fc6852

drivers/net/vxlan.c

+4 −0

Original line number	Diff line number	Diff line
		@@ -2092,6 +2092,10 @@ static struct sk_buff vxlan_na_create(struct sk_buff request,
		ns_olen = request->len - skb_network_offset(request) -
		sizeof(struct ipv6hdr) - sizeof(*ns);
		for (i = 0; i < ns_olen-1; i += (ns->opt[i+1]<<3)) {
		if (!ns->opt[i + 1]) {
		kfree_skb(reply);
		return NULL;
		}
		if (ns->opt[i] == ND_OPT_SOURCE_LL_ADDR) {
		daddr = ns->opt + i + sizeof(struct nd_opt_hdr);
		break;

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