Access to freed memory in HTTP client

==26894== Thread 3:
==26894== Invalid read of size 8
==26894== at 0x17B8E06: send_perform(_ConnInfo*, _GlobalInfo*) (http_curl.cc:336)
==26894== by 0x17B95EF: http_post(_ConnInfo*, _GlobalInfo*) (http_curl.cc:469)
==26894== by 0x17AF635: HttpConnection::HttpProcessInternal(std::string, std::string, bool, bool, bool, std::vector<std::string, std::allocator<std::string> >, boost::function<void (std::string&, boost::system::error_code&)>, http_method) (http_client.cc:232)
==26894== by 0x17B732A: boost::_mfi::mf8<void, HttpConnection, std::string, std::string, bool, bool, bool, std::vector<std::string, std::allocator<std::string> >, boost::function<void (std::string&, boost::system::error_code&)>, http_method>::operator()(HttpConnection*, std::string, std::string, bool, bool, bool, std::vector<std::string, std::allocator<std::string> >, boost::function<void (std::string&, boost::system::error_code&)>, http_method) const (mem_fn_template.hpp:958)
==26894== by 0x17B63C0: void boost::_bi::list9<boost::_bi::value<HttpConnection*>, boost::_bi::value<std::string>, boost::_bi::value<std::string>, boost::_bi::value<bool>, boost::_bi::value<bool>, boost::_bi::value<bool>, boost::_bi::value<std::vector<std::string, std::allocator<std::string> > >, boost::_bi::value<boost::function<void (std::string&, boost::system::error_code&)> >, boost::_bi::value<http_method> >::operator()<boost::_mfi::mf8<void, HttpConnection, std::string, std::string, bool, bool, bool, std::vector<std::string, std::allocator<std::string> >, boost::function<void (std::string&, boost::system::error_code&)>, http_method>, boost::_bi::list0>(boost::_bi::type<void>, boost::_mfi::mf8<void, HttpConnection, std::string, std::string, bool, bool, bool, std::vector<std::string, std::allocator<std::string> >, boost::function<void (std::string&, boost::system::error_code&)>, http_method>&, boost::_bi::list0&, int) (bind.hpp:827)
==26894== by 0x17B5078: boost::_bi::bind_t<void, boost::_mfi::mf8<void, HttpConnection, std::string, std::string, bool, bool, bool, std::vector<std::string, std::allocator<std::string> >, boost::function<void (std::string&, boost::system::error_code&)>, http_method>, boost::_bi::list9<boost::_bi::value<HttpConnection*>, boost::_bi::value<std::string>, boost::_bi::value<std::string>, boost::_bi::value<bool>, boost::_bi::value<bool>, boost::_bi::value<bool>, boost::_bi::value<std::vector<std::string, std::allocator<std::string> > >, boost::_bi::value<boost::function<void (std::string&, boost::system::error_code&)> >, boost::_bi::value<http_method> > >::operator()() (bind_template.hpp:20)
==26894== by 0x17B435D: boost::detail::function::void_function_obj_invoker0<boost::_bi::bind_t<void, boost::_mfi::mf8<void, HttpConnection, std::string, std::string, bool, bool, bool, std::vector<std::string, std::allocator<std::string> >, boost::function<void (std::string&, boost::system::error_code&)>, http_method>, boost::_bi::list9<boost::_bi::value<HttpConnection*>, boost::_bi::value<std::string>, boost::_bi::value<std::string>, boost::_bi::value<bool>, boost::_bi::value<bool>, boost::_bi::value<bool>, boost::_bi::value<std::vector<std::string, std::allocator<std::string> > >, boost::_bi::value<boost::function<void (std::string&, boost::system::error_code&)> >, boost::_bi::value<http_method> > >, void>::invoke(boost::detail::function::function_buffer&) (function_template.hpp:153)
==26894== by 0x1183637: boost::function0<void>::operator()() const (function_template.hpp:767)
==26894== by 0x17B0663: HttpClient::DequeueEvent(boost::function<void ()>) (http_client.cc:394)
==26894== by 0x17B75EB: boost::_mfi::mf1<bool, HttpClient, boost::function<void ()> >::operator()(HttpClient*, boost::function<void ()>) const (mem_fn_template.hpp:165)
==26894== by 0x17B6602: bool boost::_bi::list2<boost::_bi::value<HttpClient*>, boost::arg<1> >::operator()<bool, boost::_mfi::mf1<bool, HttpClient, boost::function<void ()> >, boost::_bi::list1<boost::function<void ()>&> >(boost::_bi::type<bool>, boost::_mfi::mf1<bool, HttpClient, boost::function<void ()> >&, boost::_bi::list1<boost::function<void ()>&>&, long) (bind.hpp:303)
==26894== by 0x17B5259: bool boost::_bi::bind_t<bool, boost::_mfi::mf1<bool, HttpClient, boost::function<void ()> >, boost::_bi::list2<boost::_bi::value<HttpClient*>, boost::arg<1> > >::operator()<boost::function<void ()> >(boost::function<void ()>&) (bind_template.hpp:32)
==26894== Address 0xe1a5b78 is 312 bytes inside a block of size 320 free'd
==26894== at 0x4C2BDEC: free (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==26894== by 0x17B9025: del_curl_handle(_ConnInfo*, _GlobalInfo*) (http_curl.cc:370)
==26894== by 0x17B8253: check_multi_info(_GlobalInfo*) (http_curl.cc:102)
==26894== by 0x17B8606: timer_cb(_GlobalInfo*) (http_curl.cc:157)
==26894== by 0x17B7FEC: multi_timer_cb(void*, long, HttpClient*) (http_curl.cc:47)
==26894== by 0x4E67817: ??? (in /usr/lib/x86_64-linux-gnu/libcurl.so.4.3.0)
==26894== by 0x4E6A4D7: curl_multi_socket_action (in /usr/lib/x86_64-linux-gnu/libcurl.so.4.3.0)
==26894== by 0x17B85B8: timer_cb(_GlobalInfo*) (http_curl.cc:149)
==26894== by 0x17B7FEC: multi_timer_cb(void*, long, HttpClient*) (http_curl.cc:47)
==26894== by 0x4E67817: ??? (in /usr/lib/x86_64-linux-gnu/libcurl.so.4.3.0)
==26894== by 0x4E68CEC: curl_multi_add_handle (in /usr/lib/x86_64-linux-gnu/libcurl.so.4.3.0)
==26894== by 0x17B8DBB: send_perform(_ConnInfo*, _GlobalInfo*) (http_curl.cc:327)
==26894==