[PATCH] clear modules' contexts in ngx_http_named_location

[Maxim Dounin]

Hello!

On Thu, Oct 13, 2011 at 03:10:25PM +0800, agentzh wrote:

> Hello!
> 
> Here attaches a patch for the nginx 1.1.5 core to fix a long standing
> bug in the ngx_http_named_location function.
> 
> I think we should clear out all the modules' contexts there just as in
> ngx_http_internal_redirect, or we'll observe weird issues due to
> left-over obsolete module contexts from the original request before
> the jump. Here is a bad case in action:
> http://www.ruby-forum.com/topic/2765027
> 
> Regards,
> -agentzh
> 
> --- nginx-1.1.5/src/http/ngx_http_core_module.c	2011-09-27
> 19:14:02.000000000 +0800
> +++ nginx-1.1.5-patched/src/http/ngx_http_core_module.c	2011-10-13
> 15:02:24.414550532 +0800
> @@ -2542,6 +2542,9 @@
>              r->content_handler = NULL;
>              r->loc_conf = (*clcfp)->loc_conf;
> 
> +            /* clear the modules contexts */
> +            ngx_memzero(r->ctx, sizeof(void *) * ngx_http_max_module);
> +
>              ngx_http_update_location_config(r);
> 
>              cmcf = ngx_http_get_module_main_conf(r, ngx_http_core_module);

I think this is a right change.

To Igor: previous discussion I was able to find is here (in 
Russian):

http://mailman.nginx.org/pipermail/nginx-ru/2009-July/026730.html

Since then, I can't recall any single case where not clearing 
module contexts was beneficial.  On the other hand, the above case 
is at least 2nd one when it strikes badly.

Maxim Dounin