vxlan: check tun_info options_len properly

[ 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>

diff --git a/drivers/net/vxlan.c b/drivers/net/vxlan.c
index b6ee0c1690d83116693eabe91bd6bbddc6bdcd53..340bd98b8dbd74a77df759b84c133c02867bcc2e 100644 (file)
--- a/drivers/net/vxlan.c
+++ b/drivers/net/vxlan.c
@@ -2049,8 +2049,11 @@ static void vxlan_xmit_one(struct sk_buff *skb, struct net_device *dev,
                label = info->key.label;
                udp_sum = !!(info->key.tun_flags & TUNNEL_CSUM);
 
-               if (info->options_len)
+               if (info->options_len) {
+                       if (info->options_len < sizeof(*md))
+                               goto drop;
                        md = ip_tunnel_info_opts(info);
+               }
        } else {
                md->gbp = skb->mark;
        }