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.
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.
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.
On 12/10/2018 7:53 AM, Alexander Sagen wrote:
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.
Somehow, during the authentication process, saslauthd manages to
segfault, seemingly due to a mutex lock issue.
Installed latest sasl2-bin (version 2.1.27) from APT (source:
http://eu-central-1.ec2.archive.ubuntu.com/ubuntu bionic/main amd64
Packages).
Running linux kernel 4.15.0-1021-aws.
gdb output during crash:
|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
<http://gnu.org/licenses/gpl.html> This is free software: you are free
to change and redistribute it. There is NO WARRANTY, to the extent
permitted by law. Type "show copying" and "show warranty" for details.
This GDB was configured as "x86_64-linux-gnu". Type "show
configuration" for configuration details. For bug reporting
instructions, please see: <http://www.gnu.org/software/gdb/bugs/>.
Find the GDB manual and other documentation resources online at:
<http://www.gnu.org/software/gdb/documentation/>. For help, type
"help". Type "apropos word" to search for commands related to
"word"... 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]
:[login=someu...@example.com] [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) |
saslauthd configuration:
|START=yes DESC="SASL Authentication Daemon" NAME="saslauthd"
MECHANISMS="pam" MECH_OPTIONS="" THREADS=0 OPTIONS="-c -m
/var/spool/postfix/var/run/saslauthd -r" |
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Jan Parcel, Software Developer
Oracle Systems Server & Cloud Engineering
