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[Brian Murray <1979933@xxxxxxxxxxxxxxxxxx>]

The verification of the Stable Release Update for net-snmp has completed
successfully and the package is now being released to -updates.
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the event that you encounter a regression using the package from
-updates please report a new bug using ubuntu-bug and tag the bug report
regression-update so we can easily find any regressions.

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https://bugs.launchpad.net/bugs/1979933

Title:
  snmptrapd Segmentation Faults When Calling my_load_defaults()

Status in net-snmp package in Ubuntu:
  Fix Released
Status in net-snmp source package in Focal:
  Fix Released

Bug description:
  [Impact]

  When starting snmptrapd configured to connect to a mysql server, we
  segmentation fault when calling my_load_defaults():

  $ sudo /usr/sbin/snmptrapd -LOw -f
  Segmentation fault (core dumped)

  (gdb) bt
  #0  0x00007efd8d9f15b0 in MEM_ROOT::Alloc (length=56, this=this@entry=0x0) at ./include/my_alloc.h:157
  #1  init_default_directories (alloc=alloc@entry=0x0) at ./mysys/my_default.cc:1632
  #2  0x00007efd8d9f817a in my_load_defaults (conf_file=0x7efd8e751f64 "my", groups=0x7efd8e7550c8, argc=0x7ffd8941b674, argv=0x7ffd8941b678, alloc=0x0, default_directories=0x555a8abccc00) at ./mysys/my_default.cc:692
  #3  0x00007efd8e74fe1b in netsnmp_mysql_init () from /lib/x86_64-linux-gnu/libnetsnmptrapd.so.35
  #4  0x0000555a8a9e3873 in main (argc=<optimized out>, argv=<optimized out>) at snmptrapd.c:1196

  What happens is that we are calling my_load_defaults() even though we
  have mysql_options(), and the arguments we pass into
  my_load_defaults() are NULL, which eventually get de-referenced.

  The fix is to change the configure script to only call
  my_load_defaults() if we don't have mysql_options().

  [Testcase]

  $ sudo apt update
  $ sudo apt install snmp snmpd snmptrapd snmp-mibs-downloader

  Edit /etc/snmp/snmptrapd.conf and add the following entries:

  disableAuthorization yes
  traphandle default /usr/bin/logger
  sqlMaxQueue 1
  sqlSaveInterval 9

  Save and exit.

  It is easier to reproduce if you stop and disable all services:

  $ sudo systemctl stop snmptrapd.service
  $ sudo systemctl stop snmpd.service

  Then try running:

  $ sudo /usr/sbin/snmptrapd -LOw -f
  Segmentation fault (core dumped)

  There is a test package available in the following ppa:

  https://launchpad.net/~mruffell/+archive/ubuntu/sf339433-test

  When running this test package, you will instead see:

  $ sudo /usr/sbin/snmptrapd -LOw -f
  mysql_real_connect() failed
  Error 2002 (HY000): Can't connect to local MySQL server through socket '/var/run/mysqld/mysqld.sock' (2)

  (I don't have a mysql server configured, but we don't segfault
  anymore).

  [Where problems can occur]

  We are changing how snmptrapd initialises and begins connections to a
  mysql server, and if a regression were to occur, it would be limited
  to users of snmptrapd with the mysql backend. Other database backends
  would not be affected.

  Other binaries produced would also not be affected.

  [Other Info]

  The issue was fixed upstream by the following commit:

  commit 011342d8e453b9e0585bf77f659d80c648df8c9f
  Author: Bart Van Assche <bvanassche@xxxxxxx>
  Date:   Sat Aug 18 09:28:14 2018 -0700
  Subject: snmptrapd: Let configure check for mysql_options()
  Link: https://github.com/net-snmp/net-snmp/commit/011342d8e453b9e0585bf77f659d80c648df8c9f

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