Windows 2012 R2 closesocket() hangs on listening socket

Question

I have a weird situation on a production server.

We have network application written on C++ which serves users requests by TCP written using IOCP.

Two days ago we did an update of Windows 2012 R2 (it installed latest security updates. The previous update was 6 month ago). And after the update when trying to stop the service we see in logs that server hangs on call to close listening socket

closesocket(session->listen_socket);

The schema of stopping the network system is the next:

1. PostQueuedCompletionStatus(m_completion_port, 0, NULL, NULL); x the number of worker threads

2. Wait all worker threads finish their job

3. CloseHandle(m_completion_port);

4. closesocket(session->accept_socket);

   closesocket(session->listen_socket);

This was working good for the last 4 years, but suddenly after Windows 2012 R2 update the server hangs forever on call closesocket(session->listen_socket);

I've alsi tried as a solution to set LINGER option with 0 timeout to make abotive closure, but it didn't help.

All ideas how to fix this or make any additional diagnostics?

Evite

first of all - look stack trace of call closesocket - where exactly code hung. are inside call NtClose or in another place – Wolcott

@Wolcott ntdll.dll!NtClose() mswsock.dll!SockCloseSocket() mswsock.dll!WSPCloseSocket() ws2_32.dll!closesocket() Unknown – Evite

this mean hang was in kernel mode driver. even don't know what in this situation do next – Wolcott

@Wolcott Here is what i've found. forum.filezilla-project.org/viewtopic.php?t=49308. Looks like windows security update causing this issue. Will try to remove an update and tell you results – Evite

@Wolcott Removing KB4338815 fixed this issue on all our servers. Thanks for help! – Evite

We have experienced this same issue with a sockets based application/service. Will Microsoft have an update of the update? – Reclusion

@MSchenkel See my answer in #51372616 for Microsoft's patch for the issue – Mediatory

thank you for cross posting this.. I appreciate it. – Reclusion

OMFG, we've been dealing with this for months before I had the good sense to use closesocket in google searches. I hadn't been thinking below the framework (Qt)! Best part is the process eventually dies, but the port remains in use but hidden in the kernel.. – Engram

Answer 1

The issue was brought by patch from Microsoft KB4338815, which caused closesocket tо hang forever on Intel Xeon processors and this was also posted by FileZilla guys in this thread https://forum.filezilla-project.org/viewtopic.php?t=49308

Evite