Bug#863520: cyrus-imapd version 2.5.10-3 Fatal error with SSL

[Philip Iezzi]

Dear maintainer,

I would greatly appreciate if you could push this fix into current Debian Stretch. The problem still persists in Cyrus-imapd 2.5.10-3 and above patch from upstream fixes it. After having upgraded a mailserver to Debian Stretch we had a massive amount of negative customer feedback complaining about dropped connections.

The patched and recompiled packages are now running for more than 2 weeks on two rather busy mail servers (datenpark.ch / onlime.ch) and all trouble has gone away, cyrus-imapd works stable again.

Thanks Vladislav for your great support!

Here's a short howto for people who never built a Deb package before:

$ apt-get source cyrus-imapd
$ wget https://github.com/cyrusimap/cyrus-imapd/commit/a1c917df8de04e108228f38f0010498bec3d81e8.patch -O cyrus-imapd-issue1872.patch 
$ cd cyrus-imapd-2.5.10/
$ patch -p1 < ../cyrus-imapd-issue1872.patch
$ apt-get build-dep cyrus-imapd
$ dpkg-buildpackage -b
$ cd ../

# install at least the following and put those packages on hold:
$ dpkg -i cyrus-common_2.5.10-3_amd64.deb cyrus-imapd_2.5.10-3_amd64.deb cyrus-pop3d_2.5.10-3_amd64.deb libcyrus-imap-perl_2.5.10-3_amd64.deb
$ echo cyrus-common hold | dpkg --set-selections
$ echo cyrus-imapd hold | dpkg --set-selections
$ echo cyrus-pop3d hold | dpkg --set-selections
$ echo libcyrus-imap-perl hold | dpkg --set-selections

# check package state
$ dpkg --get-selections | grep cyrus | grep -v deinstall

This fixes the issue and the "lib/cyrusdb_twoskip.c" fatal errors no longer pop up in mail.log

Best regards,
Philip