Same here, 302 loop when trying to enter the admin area. Frontend pages are still working. (edit: maybe they were working because they are cached to static files via .htaccess)
Remote Address:104.18.41.191:443
Request URL:https://www.***.com/wp-admin/
Request Method:GET
Status Code:302 Moved Temporarily
Response Headers
cache-control:no-cache, must-revalidate, max-age=0
cf-ray:212a20f695240e36-MXP
content-type:text/html; charset=UTF-8
date:Sat, 08 Aug 2015 09:17:33 GMT
expires:Wed, 11 Jan 1984 05:00:00 GMT
location:https://www.***.com/wp-admin/
pragma:no-cache
server:cloudflare-nginx
status:302 Moved Temporarily
version:HTTP/1.1
x-cf-powered-by:WP 1.3.18
x-powered-by:PHP/5.5.24
Request Headers
:host:www.***.com
:method:GET
:path:/wp-admin/
:scheme:https
:version:HTTP/1.1
accept:text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8
accept-encoding:gzip, deflate, sdch
accept-language:en-US,en;q=0.8,it;q=0.6
cache-control:max-age=0
cookie: [***]
upgrade-insecure-requests:1
user-agent:Mozilla/5.0 (Windows NT 10.0; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/44.0.2403.130 Safari/537.36