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To: cygwin AT cygwin DOT com
From: Michael Moats <m DOT moats AT 3arts DOT us>
Subject: Cygwin terminal fails to start after win update
Message-ID: <ae289f5e-6670-d55a-607e-f8afb0f3a785@3arts.us>
Date: Wed, 2 Sep 2020 14:32:45 -0500
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Hello. Loaded cygwin a few weeks ago, but after windows 10 update, 
mintty term fails to start.

Versions:
cygwin 3.1.6-1

OS Name    Microsoft Windows 10 Home
Version    10.0.19041 Build 19041

When problem first noticed:
Error: Could not fork child process: Resource temporarily unavailable (-1).
DLL rebasing may be required; see 'rebaseall / rebase --help'.
(and terminal allows no typing)

When attempt is made to add dll, bash and some other individual 
exceptions to firewall ASLR settings, Mintty starts & shell commands 
such as echo and pwd will work, but commands from /bin (i.e. ls, ln, 
grep, vi, cat, which) return nothing. Maybe more exceptions needed, but 
which ones?

To get cygwin working a usual, these gross windows defender firewall 
changes were made:

Windows Security
     App & browser control
         Exploit protection

Force randomization for images (Mandatory ASLR)
     Force relocation of images not compiled with /DYNAMICBASE
-> Off by default     [Mintty working]
-> On by default    [Mintyy not working]

Randomize memory allocations (Bottom-up ASLR)
     Randomize locations for virtual memory allocations.
-> Off by default     [Mintyy working]
-> On by default    [Mintyy not working]

High-entropy ASLR
     Increase variability when using Randomize memory allocations 
(Bottom-up ASLR)
-> Off by default     [Mintty working]
-> On by default    [Mintty not working]

When Cyg/Mintty is working with above gross changes:
     $ cd /usr

     $ ln -s /bin /usr/bin

     $ ls -i | grep bin
     1125899907459844 bin/
     562949954038681 sbin/

     $ cd ..

     $ ls -i | grep bin
     1125899907459844 bin/
     562949954038681 sbin/

     $ ps -ef | grep -i min
        XXXXX     649       1 ?        13:18:14 /usr/bin/mintty

Thanks in advance!!

-- Michael Moats


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