** Description changed:
[Impact]
When SSSD tries to renew the machine password, a write_to_child_fd is
open but never closed, leaking a descriptor per request until it hits
the limit and SSSD stops.
[Test Case]
1. With an AD deployed, and having the machine registered, include the
following option in sssd.conf:
# This option should only be used to test the machine account renewal task.
The option expect 2 integers seperated by a colon (':'). The first integer
defines the interval in
# seconds how often the task is run. The second specifies the inital timeout
in seconds before the task is run for the first time after startup.
# Default: 86400:750 (24h and 15m)
ad_machine_account_password_renewal_opts = 5:5
2. Restart the service and monitor the use of descriptors:
root@sssd-xenial:/home/ubuntu# while true; do ll /proc/$(pidof sssd_be)/fd |
wc -l; sleep 60; done
38
50
62
74
86
98
110
122
134
146
158
170
182
194
206
217
229
^C
+ [Regression potential]
+
+ * Small, the fix comes from upstream and it's been present for some time.
+ * A fd could still leak, or the AD machine password renewal could stop
working.
+
[Other info]
The bug is reported and fixed upstream:
https://pagure.io/SSSD/sssd/issue/3017
Upstream fix commit:
https://pagure.io/SSSD/sssd/c/312d211e03b9f3769a0362f1767cc59792e32746
Trusty is not affected (feat not implemented) and A/B/C already include
the fix :
$ git describe 312d211e03b9f3769a0362f1767cc59792e32746
sssd-1_13_4-10-g312d211e0
$ rmadison sssd
==> sssd | 1.13.4-1ubuntu1.10 | xenial-updates
- sssd | 1.15.3-2ubuntu1 | artful
- sssd | 1.16.1-1ubuntu1 | bionic
- sssd | 1.16.1-1ubuntu1 | cosmic
- sssd | 1.16.1-1ubuntu3 | cosmic-proposed
+ sssd | 1.15.3-2ubuntu1 | artful
+ sssd | 1.16.1-1ubuntu1 | bionic
+ sssd | 1.16.1-1ubuntu1 | cosmic
+ sssd | 1.16.1-1ubuntu3 | cosmic-proposed
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https://bugs.launchpad.net/bugs/1771805
Title:
AD keytab renewal task leaks a file descriptor
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