sshd: fork of unprivileged child failed

[Robin Walker <rdhw at cam dot ac dot uk>]

I have a system with Cygwin sshd installed that refuses to accept 
connections.  sshd is running and listening on port 22.

In the Windows Application Log there are, for each failed connection 
attempt, entries of the form:

sshd: PID xxxx: fatal: fork of unprivileged child failed.

In sshd.log there are entries of the form:

  1893 [main] sshd 7720 C:\cygwin\usr\sbin\sshd.exe: *** fatal error - 
recreate_mmaps_after_fork_failed
     9 [main] sshd 6788 child_copy: stack write copy failed, 
0x23DDA0..0x240000, done 0, windows pid 2350292, Win32 error 5
     7 [main] sshd 6344 fhandler_dev_zero::fixup_mmap_after_fork: 
requested 0x3F0000 != 0x0 mem alloc base 0x3F0000, state 0x1000, size 4096, 
Win32 error 487
  2029 [main] sshd 6344 C:\cygwin\usr\sbin\sshd.exe: *** fatal error - 
recreate_mmaps_after_fork_failed
     8 [main] sshd 7868 child_copy: stack write copy failed, 
0x23DDA0..0x240000, done 0, windows pid 2350292, Win32 error 5
     6 [main] sshd 6872 fhandler_dev_zero::fixup_mmap_after_fork: 
requested 0x3F0000 != 0x0 mem alloc base 0x3F0000, state 0x1000, size 4096, 
Win32 error 487
  2487 [main] sshd 6872 C:\cygwin\usr\sbin\sshd.exe: *** fatal error - 
recreate_mmaps_after_fork_failed
    10 [main] sshd 6336 child_copy: stack write copy failed, 
0x23DDA0..0x240000, done 0, windows pid 2350292, Win32 error 5


Attempts by client ssh programs to connect are given:
Read from socket failed: Connection reset by peer

This happens even for ssh 127.0.0.1 on the server itself.

What do I need to do to get this sshd working?

The first time this fault ever occurred on this system, a "rebaseall" cured 
it.  But the fault has returned some months later, and a "rebaseall" no 
longer fixes it.

--
Robin Walker (Junior Bursar), Queens' College, Cambridge CB3 9ET, UK
rdhw@cam.ac.uk  http://www.queens.cam.ac.uk/  Tel:+44 1223 335528

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