vxlan: check tun_info options_len properly

BugLink: https://bugs.launchpad.net/bugs/1853208
[ Upstream commit eadf52cf1852196a1363044dcda22fa5d7f296f7 ]

This patch is to improve the tun_info options_len by dropping
the skb when TUNNEL_VXLAN_OPT is set but options_len is less
than vxlan_metadata. This can void a potential out-of-bounds
access on ip_tun_info.

Fixes: ee122c79d422 ("vxlan: Flow based tunneling")
Signed-off-by: Xin Long <lucien.xin@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>

diff --git a/drivers/net/vxlan.c b/drivers/net/vxlan.c
index b1010a63f6a131ddc0d32b3f128c1a80b2c5ec78..e9939d25e3f08864cac9328c30fae474e75a9447 100644 (file)
--- a/drivers/net/vxlan.c
+++ b/drivers/net/vxlan.c
@@ -2331,8 +2331,11 @@ static void vxlan_xmit_one(struct sk_buff *skb, struct net_device *dev,
                vni = tunnel_id_to_key32(info->key.tun_id);
                ifindex = 0;
                dst_cache = &info->dst_cache;
-               if (info->options_len)
+               if (info->options_len) {
+                       if (info->options_len < sizeof(*md))
+                               goto drop;
                        md = ip_tunnel_info_opts(info);
+               }
                ttl = info->key.ttl;
                tos = info->key.tos;
                label = info->key.label;