gpg-agent 'crashes' with libgcrypt 1.9.0

[Vladimir Lomov]

Hello,

I'm using Archlinux x86_64 and gnupg 2.2.27 and libgcrypt 1.9.0.

Before I updated my boxes to new libgcrypt 1.9.0 (previous version was 1.8.7)
gpg worked fine, gpg-agent asked password once to sign, encrypt and decrypt
and subsequent signing, encrypting and decrypting went without password
asking (intended behaviour).

After update I noticed that I could decrypt files but cannot sign or encrypt
anything. I opened bug ticket in my distribution:
  https://bugs.archlinux.org/task/69389
where I showed output from systemd and my attempts to debug gpg-agent.

The gpg-agent is started by systemd (socket activation). With libgcrypt
1.9.0 when I want to sign or encrypt a file I successfully enter password but
after that I see (a bit cryptic) message from gpg:

  gpg: signing failed: End of file

The systemctl shows that gpg-agent was terminated (I'm not sure how exactly,
gpg-agent doesn't produce any debug information) with message:

  ...
  Jan 21 10:13:33 smoon4.bkoty.ru gpg-agent[25312]: free(): invalid pointer
  ...

This is my gpg-agent.conf:
----------------------------------- 8< --------------------------------------
pinentry-program /usr/bin/pinentry-curses
pinentry-timeout       60
# no-grab
allow-loopback-pinentry
allow-emacs-pinentry
default-cache-ttl      5400
default-cache-ttl-ssh  5400
max-cache-ttl          10800
max-cache-ttl-ssh      10800
enable-ssh-support
ssh-fingerprint-digest SHA256
----------------------------------- 8< --------------------------------------

I wasn't able to run gpg-agent in strace or gdb to figure out what is wrong,
so I follow advice of Andreas Radke to ask help here.

Would be glad to help to resolve my issue because if libgcrypt 1.9.0 would be
in "stable" area then I can't sign or encrypt files (it is interesting enough
that I could decrypt files).

---
WBR, Vladimir Lomov

-- 
"Don't worry about people stealing your ideas.	 If your ideas are any good,
you'll have to ram them down people's throats."
 -- Howard Aiken
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