Red Hat Bugzilla – Bug 1292456
sssd_be AD segfaults on missing A record
Last modified: 2016-11-04 03:14:12 EDT
This bug is created as a clone of upstream ticket:
When using sssd on CentOS 6.6 with the AD backend against a Samba 4.2 AD domain, sssd does not handle a rare failure condition; when the SRV records point at a DC but the A record for that domain controller is missing. sssd_be periodically crashes, it restarts a couple times but generally does not recover:
Dec 16 09:44:05 host kernel: sssd_be: segfault at 0 ip 00007fd12c5e018b sp 00007fffba8db420 error 4 in libsss_ad.so[7fd12c5ca000+20000]
Dec 16 09:44:05 host abrtd: Directory 'ccpp-2015-12-16-09:44:05-107682' creation detected
Dec 16 09:44:05 host abrt: Saved core dump of pid 107682 (/usr/libexec/sssd/sssd_be) to /var/spool/abrt/ccpp-2015-12-16-09:44:05-107682 (1978368 bytes)
The SIGSEGV appears to happen in sss_ldap_init_send(), src/util/sss_ldap.c:331.
Getting into this condition is rare - it's a Samba bug that I'm working on separately. The situation could probably be replicated by poisoning DNS though. My expected behavior would be to give up on this DC, try any other DCs in the Site, then try other DCs in other Sites.
I have ABRT crashes and cores / backtraces from GDB.
* master: 8bd9ec3a8885b01a34863d22aa784e221fc422fb
* sssd-1-13: b32ea7b1f91b4194e05a1a965310691075ecba23
This bug was accidentally moved from POST to MODIFIED via an error in automation, please see firstname.lastname@example.org with any questions
Verified against sssd-client-1.14.0-42.el7.x86_64 , though it's sanity *only* since we are testing against MS AD instead of Samba AD.
Removed A records for NS servers in zone file.
[root@dell-per230-02 ~]# nslookup bsod2.sssdad2012r2.com
*** Can't find bsod2.sssdad2012r2.com: No answer
[root@dell-per230-02 ~]# rm -rf /var/lib/sss/db/*
[root@dell-per230-02 ~]# service sssd restart
[root@dell-per230-02 ~]# id Administrator@sssdad2012r2.com
uid=1196000500(email@example.com) gid=1196000513(domain firstname.lastname@example.org) groups=1196000513(domain email@example.com),1196000519(enterprise firstname.lastname@example.org),1196000518(schema email@example.com),1196000512(domain firstname.lastname@example.org),1196000520(group policy creator email@example.com),1196000572(denied rodc password replication firstname.lastname@example.org)
Ran for a few hours and SSSD did not crash.
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.
For information on the advisory, and where to find the updated
files, follow the link below.
If the solution does not work for you, open a new bug report.