[libmicrohttpd] valgrind reports an invalid write in 0.9.28

[Scott Harrison]

Hi,

I am using libmicrohttpd version 0.9.28 on Linux, I am starting it as 
follows:

MHD_start_daemon(MHD_NO_FLAG, port, NULL, NULL, apc, apc_data, 
MHD_OPTION_NOTIFY_COMPLETED, rc, rc_data, MHD_OPTION_SOCK_ADDR, &addr, 
MHD_OPTION_EXTERNAL_LOGGER, microhttpd_log, NULL, MHD_OPTION_END);

and using libevent to deliver events on sockets, then running 
MHD_run_from_select with the appropriate FD sets.  Valgrind (and I have 
actually confirmed this with duma/electricfence) reports that 
MHD_connection_handle_idle (connection.c line 2424) 
---------------------------
    case MHD_EVENT_LOOP_INFO_BLOCK:
      /* we should look at this connection again in the next iteration
         of the event loop, as we're waiting on the application */
      if (0 == (connection->epoll_state & MHD_EPOLL_STATE_IN_EREADY_EDLL))
        {
->     EDLL_insert (daemon->eready_head,
                       daemon->eready_tail,
                       connection);
          connection->epoll_state |= MHD_EPOLL_STATE_IN_EREADY_EDLL;
        }
      break;
---------------------------
is writing to memory that has previously been freed.  I have been trying to 
track down the bug in my code and had a few questions regarding the 
libmicrohttpd code.  I expanded the above macro and reproduced the issue, 
it seems that eready_head is pointing to the freed memory.  My first 
question is "where are items removed from the eready_head/tail list ?"  I 
noticed that there is code in MHD_epoll, but that isn't getting used since 
I am not using epoll.  I tried to turn off epoll at configure time, but 
got:

--------------------------------
connection.c: In function 'MHD_connection_handle_idle':
connection.c:2400:29: error: 'struct MHD_Connection' has no member named 
'epoll_state'
connection.c:2401:22: error: 'struct MHD_Connection' has no member named 
'epoll_state'
connection.c:2403:4: error: 'struct MHD_Connection' has no member named 'nextE'
connection.c:2403:4: error: 'struct MHD_Daemon' has no member named 
'eready_head'
connection.c:2403:4: error: 'struct MHD_Connection' has no member named 'prevE'
connection.c:2403:4: error: 'struct MHD_Daemon' has no member named 
'eready_tail'
connection.c:2403:4: error: 'struct MHD_Daemon' has no member named 
'eready_tail'
connection.c:2403:4: error: 'struct MHD_Daemon' has no member named 
'eready_head'
connection.c:2403:4: error: 'struct MHD_Daemon' has no member named 
'eready_head'
connection.c:2406:14: error: 'struct MHD_Connection' has no member named 
'epoll_state'
connection.c:2410:29: error: 'struct MHD_Connection' has no member named 
'epoll_state'
connection.c:2411:22: error: 'struct MHD_Connection' has no member named 
'epoll_state'
connection.c:2413:4: error: 'struct MHD_Connection' has no member named 'nextE'
connection.c:2413:4: error: 'struct MHD_Daemon' has no member named 
'eready_head'
connection.c:2413:4: error: 'struct MHD_Connection' has no member named 'prevE'
connection.c:2413:4: error: 'struct MHD_Daemon' has no member named 
'eready_tail'
connection.c:2413:4: error: 'struct MHD_Daemon' has no member named 
'eready_tail'
connection.c:2413:4: error: 'struct MHD_Daemon' has no member named 
'eready_head'
connection.c:2413:4: error: 'struct MHD_Daemon' has no member named 
'eready_head'
connection.c:2416:14: error: 'struct MHD_Connection' has no member named 
'epoll_state'
connection.c:2422:27: error: 'struct MHD_Connection' has no member named 
'epoll_state'
connection.c:2424:4: error: 'struct MHD_Connection' has no member named 'nextE'
connection.c:2424:4: error: 'struct MHD_Daemon' has no member named 
'eready_head'
connection.c:2424:4: error: 'struct MHD_Connection' has no member named 'prevE'
connection.c:2424:4: error: 'struct MHD_Daemon' has no member named 
'eready_tail'
connection.c:2424:4: error: 'struct MHD_Daemon' has no member named 
'eready_tail'
connection.c:2424:4: error: 'struct MHD_Daemon' has no member named 
'eready_head'
connection.c:2424:4: error: 'struct MHD_Daemon' has no member named 
'eready_head'
connection.c:2427:14: error: 'struct MHD_Connection' has no member named 
'epoll_state'
------------------------------------

What things should I be checking in my code ? am I using the library 
incorrectly ?

Many thanks

Scott.