[nginx] map module cause core dump

[Maxim Dounin]

Hello!

On Thu, May 19, 2016 at 01:03:14PM +0800, 洪志道 wrote:

> Hi,
> 
> It seems the following configure will cause core dump file.
> 
> map $uri $s {
>     default  $s;  # same var name as the var generated by map directive
> above
> }
> 
> server {
>     listen  80;
> 
>     location / {
>         return 200 $s;
>     }
> }

This is a classical example of infinite recursion.  It's expected 
to work fine on any host with infinite amount of memory, but 
you've probably tried it on a host with some limited amount of 
memory available.  Avoid writing such configurations on hosts with 
limited amount of memory.

Jokes aside, the result is expected.  We've considered adding a 
protection from such types of recursion (much like what we do with 
subrequests and internal redirections), but yet think it would be 
an overkill.

-- 
Maxim Dounin
http://nginx.org/