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We have seen severe mutex issues with sasl_client init on super-fast
machines. We temporarily solved it by patching openldap to ensure
it never calls sasl_client_init more than once, but when I get out
from under my current non-cyrus-sasl load, I had planned to test and
submit changes to sasl_*_init to use a static mutext that is
pre-initialized, which is what I found online as the solution for
LIBRARY issues with passed in or even local mutexts.<br>
<div class="moz-forward-container"> <br>
The issue is that the mutex needs a mutex, which needs a mutex,
and it's turtles all the way down unless a static mutex is used at
that top level.<br>
<br>
For some reason I have not understood, I've been told to not even
THINK of doing anything like that to the mutexes used in gssapi.<br>
<br>
<br>
<div class="moz-cite-prefix">On 12/10/2018 7:53 AM, Alexander
Sagen wrote:<br>
</div>
<blockquote type="cite"
cite="mid:cyrusimap%2Fcyrus-sasl%2Fissues%2F547@github.com">
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<p>Trying to set up a temporary shared email server to replace
an old server with a dying disk while we move all our
customers to a new email solution. Configured saslauthd the
same way it was configured on the old server.</p>
<p>Somehow, during the authentication process, saslauthd manages
to segfault, seemingly due to a mutex lock issue.</p>
<p>Installed latest sasl2-bin (version 2.1.27) from APT (source:
<a href="http://eu-central-1.ec2.archive.ubuntu.com/ubuntu"
rel="nofollow" moz-do-not-send="true">http://eu-central-1.ec2.archive.ubuntu.com/ubuntu</a>
bionic/main amd64 Packages).</p>
<p>Running linux kernel 4.15.0-1021-aws.</p>
<p>gdb output during crash:</p>
<pre><code>root@mail1:~# gdb --args /usr/sbin/saslauthd -a pam -c -m /var/spool/postfix/var/run/saslauthd -r -n 0 -d
GNU gdb (Ubuntu 8.1-0ubuntu3) 8.1.0.20180409-git
Copyright (C) 2018 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <a class="moz-txt-link-rfc2396E" href="http://gnu.org/licenses/gpl.html" moz-do-not-send="true"><http://gnu.org/licenses/gpl.html></a>
This is free software: you are free to change and redistribute it.
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and "show warranty" for details.
This GDB was configured as "x86_64-linux-gnu".
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Reading symbols from /usr/sbin/saslauthd...(no debugging symbols found)...done.
(gdb) run
Starting program: /usr/sbin/saslauthd -a pam -c -m /var/spool/postfix/var/run/saslauthd -r -n 0 -d
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
saslauthd[4767] :num_procs : 0
saslauthd[4767] :mech_option: NULL
saslauthd[4767] :run_path : /var/spool/postfix/var/run/saslauthd
saslauthd[4767] :auth_mech : pam
saslauthd[4767] :mmaped shared memory segment on file: /var/spool/postfix/var/run/saslauthd/cache.mmap
saslauthd[4767] :bucket size: 96 bytes
saslauthd[4767] :stats size : 36 bytes
saslauthd[4767] :timeout : 28800 seconds
saslauthd[4767] :cache table: 985828 total bytes
saslauthd[4767] :cache table: 1711 slots
saslauthd[4767] :cache table: 10266 buckets
saslauthd[4767] :flock file opened at /var/spool/postfix/var/run/saslauthd/cache.flock
saslauthd[4767] :master pid is: 0
saslauthd[4767] :listening on socket: /var/spool/postfix/var/run/saslauthd/mux
saslauthd[4767] :attempting a read lock on slot: 1501
saslauthd[4767] :[<a class="moz-txt-link-abbreviated" href="mailto:login=someuser@example.com" moz-do-not-send="true">login=someuser@example.com</a>] [service=smtp] [realm=example.com]: not found, update pending
saslauthd[4767] :attempting to release lock on slot: 1501
Program received signal SIGSEGV, Segmentation fault.
__GI___pthread_mutex_lock (mutex=0x20) at ../nptl/pthread_mutex_lock.c:65
65 ../nptl/pthread_mutex_lock.c: No such file or directory.
(gdb)
</code></pre>
<p>saslauthd configuration:</p>
<pre><code>START=yes
DESC="SASL Authentication Daemon"
NAME="saslauthd"
MECHANISMS="pam"
MECH_OPTIONS=""
THREADS=0
OPTIONS="-c -m /var/spool/postfix/var/run/saslauthd -r"
</code></pre>
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<pre class="moz-signature" cols="72">--
Jan Parcel, Software Developer
Oracle Systems Server & Cloud Engineering</pre>
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