at least for me it didn't fix. still see in logs: Error: lzma.read(/var/spool/mail/telsch/storage/m.11800): corrupted data at 110015

before i upgrade from 2.3.4.1 to 2.3.8 + your patch i noticed i can access the mails with alpine and roundcube but not with thunderbird.

On 10.10.19 11:38, Timo Sirainen via dovecot wrote:

Can you test if https://github.com/dovecot/core/commit/5068b11e594ad7cc1f7cedf2bd9280520e0e5... fixes it for you?

...

On 10 Oct 2019, at 11.34, MAREN ZUBIZARRETA via dovecot <dovecot@dovecot.org <mailto:dovecot@dovecot.org>> wrote:

Hello: I have found the same problem reported above by Patrick Cernko affecting our system and corrupting our messages. Even worse, Outlook 2016 will no synchronize and the clients cannot see any message, even if there is only one corrupted mail per mailbox. I cannot figure out a feasible workaround for our system, and I can see that in new version 2.38 the bug is not fixed. Will this issue be treated soon? Thanks a lot Maren Zubizarreta

WARNING: using attachment_dir with plugin zlib can corrupt mails

*Patrick Cernko*pcernko at mpi-klsb.mpg.de <mailto:dovecot%40dovecot.org?Subject=Re:%20Re%3A%20WARNING%3A%20using%20attachment_dir%20with%20plugin%20zlib%20can%20corrupt%20mails&In-Reply-To=%3C1ab8edcc-bef4-3b41-d09a-c523674a5031%40mpi-klsb.mpg.de%3E> /Fri Jul 19 17:52:37 EEST 2019/

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---

Hello list, hello Dovecot developers, this week, I discovered a serious bug in Dovecot, that lead to several broken mails on our servers. The bug corrupts the first few characters of the mail header during saving. On our setup, it was almost always only the very first line of text, that was corrupted. Depending on the IMAP client (they seem to request different header fields, ... during mail access), the bug causes the imap process to hang up the TCP connection and log errors like this:

...

/imap(USERNAME)<4767><TeQP4ASOTK5/AAAB>: Error: Corrupted record in index cache file /IMAP/mail/mailboxes/USERNAME/mdbox/mailboxes/Trash/dbox-Mails/dovecot.index.cache: UID 489113: Broken fields in mailbox Trash: read(attachments-connector(zlib(/IMAP/mail/mailboxes/USERNAME/mdbox/storage/m.813))): FETCH BODY[HEADER.FIELDS (RETURN-PATH SUBJECT)] got too little data: 2 vs 122/ In our case that finally grabbed my attention, the client was the users iphone that did not display any new messages but his Thunderbird did. The bug seems to be triggered by a bad "interaction" of attachment_dir option and zlib plugin. If you use both, you most likely are affected, too, except you only use zlib plugin for reading previously compressed stored mails. That's also the workaround we use now: zlib plugin only enabled in mail_plugins but no plugin/zlib_save set. The bug occurs on very specific mails. Due to privacy reasons I could not provide sample mails here. Storing such mails seems to trigger the bug reproducible. I attached a very minimal doveconf -n config, that can be used to trigger the bug. If one of the developers is interested, I can try to generate an "anonymized" version of such a specific mail that still causes the issue. I discovered the bug on our productive systems, running latest Dovecot 2.2 release, but the latest 2.3 I used during debugging is affected, too. During debugging, I also found one hint, that might help find the bug: If you store a problematic mail with zlib_save=gz (or zlib_save=bz2) and then disable the zlib plugin in mail_plugins, you can call doveadm fetch -u test hdr all | grep -v ^hdr: | gzip --decompress on test's mailbox with only that one broken mail. This will display the beginning of the rfc822 mail text until gzip terminates with "gzip: stdin: unexpected end of file", approximately after twice the length of the mail HEADER. This might indicate, that dovecot stores the uncompressed size of the header in it's data structures although the mail is stored compressed. I also found a very efficient way to find all affected mails in our setup: doveadm -f flow fetch -A 'user guid mailbox uid seq flags hdr' all |
grep -a "^[^ ]+ user=" |
grep -avF ' hdr=Return-path: ' |
grep -av '.* hdr=[[:print:][:space:]]*$' (runtime for ~6M mails on our servers was 20-30min) This can be even more optimized if you have a powerful storage system with GNU parallel: /doveadm user '*' | parallel "doveadm -f flow fetch -u '{}' 'user guid mailbox uid seq flags hdr' all | grep -a '^user=' | grep -avF ' hdr=Return-path: ' | grep -av '.* hdr=[[:print:][:space:]]*$' || true"/ (runtime for ~6M mails on our servers was ~4min) The command will give you a list of mails that possibly are affected, check the full output of doveadm fetch -u USERNAME hdr guid GUID | less to verify that the header is really broken. On our systems I found 39 mails within ~12M mails. I was able to recover these mails "manually" by reconstructing the Return-Path header line, importing the fixed mails and expunging the corrupt ones. Before importing, I had to disable zlib_save option obviously. Best regards,

Patrick Cernko <pcernko at mpi-klsb.mpg.de <https://dovecot.org/mailman/listinfo/dovecot>> +49 681 9325 5815 Joint Administration: Information Services and Technology Max-Planck-Institute fuer Informatik & Softwaresysteme

On 06/11/2019 16:15 telsch via dovecot <dovecot@dovecot.org> wrote:

Hello list,

i'm running an internal dovecot instance with working managesieve. But on my external dovecot-proxy instance i got an internal error. Nothing logs on internal dovecot.

It seems you are trying to connect to STARTTLS port using SSL. You should probably tell in your passdb that the connection needs to use STARTTLS security, or configure the backend listener with ssl=yes.

Aki

You are hardcoding the port. I'm pretty sure your managesieve is not listening on 143 =)

Aki

On 06/11/2019 16:46 telsch via dovecot <dovecot@dovecot.org> wrote:

If i change it to:

passdb { args = /etc/dovecot-proxy/dovecot-ldap-passdb.conf.ext default_fields = proxy=y host=server.intra.lan port=143 starttls=yes master=proxy pass=#hidden_use-P_to_show# driver = ldap }

I still got the same error for mangesieve. IMAP login works with both SSL/STARTTLS.

On 11/6/19 3:19 PM, Aki Tuomi via dovecot wrote:

...

...

On 06/11/2019 16:15 telsch via dovecot <dovecot@dovecot.org> wrote:

Hello list,

i'm running an internal dovecot instance with working managesieve. But on my external dovecot-proxy instance i got an internal error. Nothing logs on internal dovecot.

It seems you are trying to connect to STARTTLS port using SSL. You should probably tell in your passdb that the connection needs to use STARTTLS security, or configure the backend listener with ssl=yes.

Aki

I need a more detailed hint. Dovecot proxy IMAP is running fine, but how to add to the same proxy managesieve support?

I thougt it's activated in the proxy: protocols = imap sieve

In the passdb proxy to the backends SSL or STARTTLS port successfully for IMAP. What exactly missing for managesieve?

Thanks!

On 11/6/19 3:52 PM, Sami Ketola via dovecot wrote:

Also those variables can't be returned from passdb as they are needed pre-auth.

Sami

...

On 6 Nov 2019, at 16.51, Aki Tuomi via dovecot <dovecot@dovecot.org> wrote:

You are hardcoding the port. I'm pretty sure your managesieve is not listening on 143 =)

Aki

...

On 06/11/2019 16:46 telsch via dovecot <dovecot@dovecot.org> wrote:

If i change it to:

passdb { args = /etc/dovecot-proxy/dovecot-ldap-passdb.conf.ext default_fields = proxy=y host=server.intra.lan port=143 starttls=yes master=proxy pass=#hidden_use-P_to_show# driver = ldap }

I still got the same error for mangesieve. IMAP login works with both SSL/STARTTLS.

On 11/6/19 3:19 PM, Aki Tuomi via dovecot wrote:

...

...

On 06/11/2019 16:15 telsch via dovecot <dovecot@dovecot.org> wrote:

Hello list,

i'm running an internal dovecot instance with working managesieve. But on my external dovecot-proxy instance i got an internal error. Nothing logs on internal dovecot.

It seems you are trying to connect to STARTTLS port using SSL. You should probably tell in your passdb that the connection needs to use STARTTLS security, or configure the backend listener with ssl=yes.

Aki

Ah ok thanks, now i got it!

I need to change default_fields = proxy=y host=server.intra.lan port=993 ssl=yes master=proxy pass=#hidden_use-P_to_show#

to default_fields = proxy=y host=server.intra.lan starttls=yes master=proxy pass=#hidden_use-P_to_show#

and enable STARTTLS for IMAP on the backend.

Thanks!

On 11/6/19 5:05 PM, Aki Tuomi via dovecot wrote:

As mentioned on earlier email, are you sure you are connecting to port 4190 and not 143 for ManageSieve?

Aki

...

On 06/11/2019 17:48 telsch via dovecot <dovecot@dovecot.org> wrote:

I need a more detailed hint. Dovecot proxy IMAP is running fine, but how to add to the same proxy managesieve support?

I thougt it's activated in the proxy: protocols = imap sieve

In the passdb proxy to the backends SSL or STARTTLS port successfully for IMAP. What exactly missing for managesieve?

Thanks!

On 11/6/19 3:52 PM, Sami Ketola via dovecot wrote:

...

Also those variables can't be returned from passdb as they are needed pre-auth.

Sami

...

On 6 Nov 2019, at 16.51, Aki Tuomi via dovecot <dovecot@dovecot.org> wrote:

You are hardcoding the port. I'm pretty sure your managesieve is not listening on 143 =)

Aki

...

On 06/11/2019 16:46 telsch via dovecot <dovecot@dovecot.org> wrote:

If i change it to:

passdb { args = /etc/dovecot-proxy/dovecot-ldap-passdb.conf.ext default_fields = proxy=y host=server.intra.lan port=143 starttls=yes master=proxy pass=#hidden_use-P_to_show# driver = ldap }

I still got the same error for mangesieve. IMAP login works with both SSL/STARTTLS.

On 11/6/19 3:19 PM, Aki Tuomi via dovecot wrote:

...

> On 06/11/2019 16:15 telsch via dovecot <dovecot@dovecot.org> wrote: > > > Hello list, > > i'm running an internal dovecot instance with working managesieve. But > on my external dovecot-proxy instance i got an internal error. Nothing > logs on internal dovecot. > >

It seems you are trying to connect to STARTTLS port using SSL. You should probably tell in your passdb that the connection needs to use STARTTLS security, or configure the backend listener with ssl=yes.

Aki