From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.3.2 (2011-06-06) on dcvr.yhbt.net X-Spam-Level: X-Spam-ASN: X-Spam-Status: No, score=-2.9 required=3.0 tests=ALL_TRUSTED,BAYES_00, T_RP_MATCHES_RCVD shortcircuit=no autolearn=unavailable version=3.3.2 X-Original-To: yahns-public@yhbt.net Received: from localhost (dcvr.yhbt.net [127.0.0.1]) by dcvr.yhbt.net (Postfix) with ESMTP id 1FAC31FAAF for ; Fri, 8 May 2015 22:24:29 +0000 (UTC) From: Eric Wong To: yahns-public@yhbt.net Subject: [PATCH] proxy_pass: fix race condition due to ensure Date: Fri, 8 May 2015 22:24:29 +0000 Message-Id: <1431123869-1937-1-git-send-email-e@80x24.org> List-Id: When calling proxy_busy_mod_blocked to re-enable a descriptor via epoll, the ensure block is dangerous because the "ensure" clause modifies the object after the ReqRes is injected into epoll. This is extremely dangerous as we give up exclusive access to the object once we call epoll_ctl. This simplifies the code a bit while we're at it. --- lib/yahns/proxy_http_response.rb | 34 +++++++++++++++------------------- 1 file changed, 15 insertions(+), 19 deletions(-) diff --git a/lib/yahns/proxy_http_response.rb b/lib/yahns/proxy_http_response.rb index 5bb0608..90a9395 100644 --- a/lib/yahns/proxy_http_response.rb +++ b/lib/yahns/proxy_http_response.rb @@ -47,6 +47,13 @@ module Yahns::HttpResponse # :nodoc: wbuf.wbuf_abort if wbuf end + def wait_on_upstream(req_res, alive, wbuf) + req_res.resbuf = wbuf || Yahns::Wbuf.new(nil, alive, + self.class.output_buffer_tmpdir, + false) + :wait_readable # self remains in :ignore, wait on upstream + end + # returns :wait_readable if we need to read more from req_res # returns :ignore if we yield control to the client(self) # returns nil if completely done @@ -58,8 +65,7 @@ module Yahns::HttpResponse # :nodoc: have_body = !Rack::Utils::STATUS_WITH_NO_ENTITY_BODY.include?(si) && env[REQUEST_METHOD] != HEAD flags = MSG_DONTWAIT - k = self.class - alive = @hs.next? && k.persistent_connections + alive = @hs.next? && self.class.persistent_connections res = "HTTP/1.1 #{status}\r\n" headers.each do |key,value| # n.b.: headers is an Array of 2-element Arrays @@ -101,9 +107,7 @@ module Yahns::HttpResponse # :nodoc: when nil # premature EOF return proxy_err_response(nil, req_res, nil, wbuf) when :wait_readable - # for ensure: - wbuf ||= Yahns::Wbuf.new(nil, alive, k.output_buffer_tmpdir, false) - return :wait_readable # self remains in :ignore, wait on upstream + return wait_on_upstream(req_res, alive, wbuf) end until len == 0 elsif kcar.chunked? # nasty chunked body @@ -116,9 +120,7 @@ module Yahns::HttpResponse # :nodoc: when nil # premature EOF return proxy_err_response(nil, req_res, nil, wbuf) when :wait_readable - # for ensure: - wbuf ||= Yahns::Wbuf.new(nil, alive, k.output_buffer_tmpdir, false) - return :wait_readable # self remains in :ignore, wait on upstream + return wait_on_upstream(req_res, alive, wbuf) end until kcar.body_eof? buf = tmp @@ -129,9 +131,7 @@ module Yahns::HttpResponse # :nodoc: when String buf << rv when :wait_readable - # for ensure: - wbuf ||= Yahns::Wbuf.new(nil, alive, k.output_buffer_tmpdir, false) - return :wait_readable + return wait_on_upstream(req_res, alive, wbuf) when nil # premature EOF return proxy_err_response(nil, req_res, nil, wbuf) end # no loop here @@ -147,21 +147,17 @@ module Yahns::HttpResponse # :nodoc: req_res.shutdown break when :wait_readable - # for ensure: - wbuf ||= Yahns::Wbuf.new(nil, alive, k.output_buffer_tmpdir, false) - return :wait_readable # self remains in :ignore, wait on upstream + return wait_on_upstream(req_res, alive, wbuf) end while true end end - wbuf and return proxy_busy_mod_blocked(wbuf, wbuf.busy) - proxy_busy_mod_done(alive) + return proxy_busy_mod_done(alive) unless wbuf + req_res.resbuf = wbuf + proxy_busy_mod_blocked(wbuf, wbuf.busy) rescue => e proxy_err_response(502, req_res, e, wbuf) - ensure - # this happens if this method returns :wait_readable - req_res.resbuf = wbuf if wbuf end def proxy_response_finish(kcar, wbuf, req_res) -- EW