From 1e63bed66aa932aab75d5a67bbfce005fc252bf5 Mon Sep 17 00:00:00 2001 From: Ido Schimmel Date: Mon, 1 Jun 2020 15:58:55 +0300 Subject: [PATCH] vxlan: Avoid infinite loop when suppressing NS messages with invalid options [ Upstream commit 8066e6b449e050675df48e7c4b16c29f00507ff0 ] 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: 4b29dba9c085 ("vxlan: fix nonfunctional neigh_reduce()") Signed-off-by: Ido Schimmel Acked-by: Nikolay Aleksandrov Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- drivers/net/vxlan.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/drivers/net/vxlan.c b/drivers/net/vxlan.c index 58ddb6c90418..b1470d30d079 100644 --- a/drivers/net/vxlan.c +++ b/drivers/net/vxlan.c @@ -1521,6 +1521,10 @@ static struct sk_buff *vxlan_na_create(struct sk_buff *request, daddr = eth_hdr(request)->h_source; ns_olen = request->len - skb_transport_offset(request) - 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;