Commit 53fc6852 authored by Ido Schimmel's avatar Ido Schimmel Committed by David S. Miller

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

When neighbor suppression is enabled the bridge 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 bridge 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: ed842fae ("bridge: suppress nd pkts on BR_NEIGH_SUPPRESS ports")
Signed-off-by: default avatarIdo Schimmel <idosch@mellanox.com>
Reported-by: default avatarAlla Segal <allas@mellanox.com>
Tested-by: default avatarAlla Segal <allas@mellanox.com>
Acked-by: default avatarNikolay Aleksandrov <nikolay@cumulusnetworks.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent dafe2078
...@@ -276,6 +276,10 @@ static void br_nd_send(struct net_bridge *br, struct net_bridge_port *p, ...@@ -276,6 +276,10 @@ static void br_nd_send(struct net_bridge *br, struct net_bridge_port *p,
ns_olen = request->len - (skb_network_offset(request) + ns_olen = request->len - (skb_network_offset(request) +
sizeof(struct ipv6hdr)) - sizeof(*ns); sizeof(struct ipv6hdr)) - sizeof(*ns);
for (i = 0; i < ns_olen - 1; i += (ns->opt[i + 1] << 3)) { for (i = 0; i < ns_olen - 1; i += (ns->opt[i + 1] << 3)) {
if (!ns->opt[i + 1]) {
kfree_skb(reply);
return;
}
if (ns->opt[i] == ND_OPT_SOURCE_LL_ADDR) { if (ns->opt[i] == ND_OPT_SOURCE_LL_ADDR) {
daddr = ns->opt + i + sizeof(struct nd_opt_hdr); daddr = ns->opt + i + sizeof(struct nd_opt_hdr);
break; break;
......
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