mod_lua: Crash in websockets PING handling

How it was found

A stack recursion crash in the mod_lua module was found. A Lua script executing the r:wsupgrade() function could crash the process if a malicious client sent a carefully crafted PING request. This issue affected releases 2.4.7 through 2.4.12 inclusive.

https://httpd.apache.org/security/vulnerabilities_24.html