What version of shadowsocks-libev are you using?

shadowsocks-libev-3.1.0

What operating system are you using?

Ubuntu 16.04 64 bit

What did you do?

In parsing json configuration file, two of the properties ("mode", "plugin") do not perform null checking before invoking strlen,

feeding null json value to "mode" or "plugin" property will trigger process crash.

PoC:

(py3) ➜  src   ./ss-server -c config.json
[1]    28610 segmentation fault (core dumped)  ./ss-server -c config.json
(py3) ➜  src   cat config.json
{
    "server":"my_server_ip",
    "server_port":8388,
    "local_address": "127.0.0.1",
    "local_port":1080,
    "password":"mypassword",
    "timeout":300,
    "method":"aes-256-cfb",
    "fast_open": false,
    "plugin": null
}

What did you expect to see?

What did you see instead?

What is your config in detail (with all sensitive info masked)?

Regards,
Alex, SourceBrella Inc.