While using ipvlan docker plugin in l3 mode, the route table with a runc container is setup as

root@6ad93a9c8180:/# ip route
default dev eth0 scope link 
192.168.120.0/24 dev eth0 proto kernel scope link src 192.168.120.2 

While adding the routes with Kata Containers, you get an error:

docker: Error response from daemon: OCI runtime create failed: rpc error: code = Internal desc = Could not add route dest()/gw()/dev(eth0): one of Dst.IP, Src, or Gw must not be nil: unknown.

This is because source, destination and gateway all are null.
We should set the gateway to "0.0.0.0" in this case, as
ip route add default dev eth0 scope link is equivalent to ip route add default via 0.0.0.0 dev eth0 scope link.