Created attachment 30397 [details]
patch for the reported bug

mod_cache_socache is the intermediary layer between mod_cache and e.g. mod_socache_memcache. In order to activate such a socache provider you would typically use a directive like

    CacheSocache memcache:localhost:11211

Unfortunately the parsing code for this directive in modules/cache/mod_cache_socache.c is buggy.

In lines 1264 - 1273 it correctly parses the name of the socache_provider into a variable "name" (as the directives argument resides in variable "arg" but this can also contain configuration arguments after the colon).

Unfortunately in lines 1275-1276 it tries to verify the existence of the socache_provider against the variable "arg" instead of "name".
The effect of this is, that a directive "CacheSocache" without any additional arguments passes this check, but the socache_provider doesn't get any additional configuration values. If you use "CacheSocache" with any configuring arguments, the check compares the whole directive's argument against the valid socache_providers and fails.

Using the variable "name" in line 1276 instead of "arg" fixes the problem.
(see attacched patch against rev 1489734.

Please apologize if this is a duplicate, but I couldn't find this bug reported elsewhere. Also this bug is present in version 2.4.4 as well and I used mod_cache as a components as mod_cache_socache is missing as component.