diff mbox series

[net,2/2] vxlan: Avoid infinite loop when suppressing NS messages with invalid options

Message ID 20200601125855.1751343-3-idosch@idosch.org
State New
Headers show
Series Fix infinite loop in bridge and vxlan modules | expand

Commit Message

Ido Schimmel June 1, 2020, 12:58 p.m. UTC 
From: Ido Schimmel <idosch@mellanox.com>

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 <idosch@mellanox.com>
---
 drivers/net/vxlan.c | 4 ++++
 1 file changed, 4 insertions(+)
diff mbox series

Patch

diff --git a/drivers/net/vxlan.c b/drivers/net/vxlan.c
index a5b415fed11e..779e56c43d27 100644
--- a/drivers/net/vxlan.c
+++ b/drivers/net/vxlan.c
@@ -1924,6 +1924,10 @@  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;