Nginx disable php upload and execution

Currently i'm running local forum with image upload,recently few attackers try to use my server as phising mail sender by uploading php based file,i was try some nginx config but it seems not worked here is part of my nginx conf

try_files $uri =404;
location /upload_path  {
types
{
image/gif gif;
image/jpeg jpeg jpg;
image/png png;
text/plain txt;
}
default_type application/octet-stream;
 
location ~ \.php$
{
break;
}
}

any advice to avoid php file upload and execution?

http://ift.tt/1dvHQ0Z