FS#65017 - [Exim] crashes with SIGABRT trying to send an email to relay

Attached to Project: Community Packages
Opened by Filipp Andjelo (scorp) - Thursday, 02 January 2020, 19:25 GMT
Last edited by Felix Yan (felixonmars) - Monday, 15 June 2020, 15:18 GMT
Task Type Bug Report
Category Packages
Status Closed
Assigned To Felix Yan (felixonmars)
Architecture x86_64
Severity Critical
Priority Normal
Reported Version
Due in Version Undecided
Due Date Undecided
Percent Complete 100%
Votes 2
Private No

Details

Description:

After upgrading exim from version 4.92.3 to the latest version 4.93.2 the application starts crashing with SIGABRT(6) when trying to send an email to the ISP relay (remote_host). Falling back to the previous version fixes the problem and the application is able to send emails with the very same configuration.

I don't know yet, what exactly leads to this crash. Here are some lines from the journal log:
exim[9375]: munmap_chunk(): invalid pointer
kernel: audit: type=1701 audit(1577991522.875:4601): auid=4294967295 uid=79 gid=79 ses=4294967295 pid=9375 comm="exim" exe="/usr/bin/exim" sig=6 res=1
audit[9375]: ANOM_ABEND auid=4294967295 uid=79 gid=79 ses=4294967295 pid=9375 comm="exim" exe="/usr/bin/exim" sig=6 res=1

Looks like a double free of the same memory. I think, this is a bug in the software, rather, then a packaging one. However, people should know, that updating to the latest version could lead to this critical error, where an email server stops working.

Steps to reproduce:
1) Install exim 4.93.2
2) Modify configuration to use a remote_host to send external mails
3) Connect to the mail server through your SMTP client (Thunderbird, Claws Mail etc.) and try to send any mail to foreign server, this should fail.
4) Look for munmap_chunk() error on the journal log


This task depends upon

Closed by  Felix Yan (felixonmars)
Monday, 15 June 2020, 15:18 GMT
Reason for closing:  Fixed
Additional comments about closing:  4.94
Comment by Filipp Andjelo (scorp) - Thursday, 02 January 2020, 19:30 GMT
Oops, forgot to add proper task name :)

Is it not possible to do afterwards? Or am I blind?

Can s.o. please set the right name for me? Thx
Exim crashes with SIGABRT trying to send an email to relay

Comment by Caleb Maclennan (alerque) - Wednesday, 03 June 2020, 20:47 GMT
Seeing this too, mail server can't authenticate any users to send outgoing mail, systemd logs are jammed with the errors mentioned.
Comment by Caleb Maclennan (alerque) - Wednesday, 03 June 2020, 20:49 GMT
> 2) Modify configuration to use a remote_host to send external mails

I'm not even doing this. The only thing interesting in my config is using LDAP to authenticate LOGINs. Config unchanged from previously working versions.
Comment by Caleb Maclennan (alerque) - Wednesday, 03 June 2020, 21:03 GMT
This has something to do with Arch's PLAIN and LOGIN definitions.
Comment by Caleb Maclennan (alerque) - Wednesday, 03 June 2020, 21:59 GMT
The 4.94 release that just hit [community] in the 2 hours since I started trying to fix this seems to resolve the problem.
Comment by Caleb Maclennan (alerque) - Thursday, 04 June 2020, 11:14 GMT
I think this can probably be closed, I've confirmed it's not a problem on 4.94 the way it was on 4.93.

Unfortunately the 4.94 release has it's own issues: https://bugs.archlinux.org/index.php?do=details&action=details.addvote&task_id=66894
Comment by Filipp Andjelo (scorp) - Thursday, 11 June 2020, 21:41 GMT
I'm scared to touch my server. On one hand I downgraded exim to 4.92 to get it running again, on the other hand, by the latest news, it has a critical security issue and has to be upgraded to the latest version. And I'm using LDAP through PAM, where obviously this thing shouldn't work again.... oh boy... :)
Comment by Caleb Maclennan (alerque) - Monday, 15 June 2020, 06:40 GMT
@scorp The PAM issue has been patched in the latest Arch Linux build. I'm using it with combo LDAP + PAM authentication checks. Do go through your config updating it against the example one but as far as I can tell everything works again.
Comment by Filipp Andjelo (scorp) - Monday, 15 June 2020, 14:56 GMT
I just upgraded to 4.94 and the issue seems to be fixed there. I think, this ticket can be closed.

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