autobuild[sn-devel-144]: intermittent test failure detected

[autobuild]

The autobuild test system (on sn-devel-144) has detected an intermittent failing test in 
the current master tree.

The autobuild log of the failure is available here:

   https://git.samba.org/autobuild.flakey.sn-devel-144/2018-12-03-0655/flakey.log

The failure seems to be in the "samba-purepy3-ad-dc-2" suite, whose build logs are available here:

   https://git.samba.org/autobuild.flakey.sn-devel-144/2018-12-03-0655/samba-purepy3-ad-dc-2.stderr
   https://git.samba.org/autobuild.flakey.sn-devel-144/2018-12-03-0655/samba-purepy3-ad-dc-2.stdout
  
The top commit at the time of the failure was:

commit 46a6c6ff6d2fc68e313bcb2cd2c65b5a6e7c1782
Author: Ralph Boehme <slow at samba.org>
Date:   Fri Nov 30 10:27:19 2018 +0100

    vfs_fruit: avoid dereferencing fsp->base_fsp in fruit_fstat_meta_stream()
    
    This helps avoiding a NULL dereference on systems where additional
    patches modify the following condition in open_file()
    
      if ((open_access_mask & (FILE_READ_DATA|FILE_WRITE_DATA|FILE_APPEND_DATA|FILE_EXECUTE)) ||
          (!file_existed && (local_flags & O_CREAT)) ||
          ((local_flags & O_TRUNC) == O_TRUNC) ) {
    
    to
    
      if ((open_access_mask & (FILE_READ_DATA|FILE_WRITE_DATA|FILE_APPEND_DATA|FILE_EXECUTE|DELETE_ACCESS)) ||
          (!file_existed && (local_flags & O_CREAT)) ||
          ((local_flags & O_TRUNC) == O_TRUNC) ) {
    
    Ie addtionally check open_access_mask against DELETE_ACCESS. As a result
    opens with DELETE_ACCESS go through the code that does an fd_open() plus
    a subsequent fstat().
    
    That will trigger a crash in fruit_fstat_meta_stream() when a client
    wants to delete a file for deletion. When we open base file for delete,
    we call open_streams_for_delete() which internally calls create-file
    with NTCREATEX_OPTIONS_PRIVATE_STREAM_DELETE which prevents opening of
    the base_fsp. Voila, combined with the change described above you get a
    NULL deref.
    
    Signed-off-by: Ralph Boehme <slow at samba.org>
    Reviewed-by: Jeremy Allison <jra at samba.org>
    
    Autobuild-User(master): Jeremy Allison <jra at samba.org>
    Autobuild-Date(master): Sun Dec  2 07:52:34 CET 2018 on sn-devel-144

and the last 50 lines of the stdout log were:


* Comparing [CONFIGURATION] context...

* DN lists have different size: 1619 != 1618

* DNs found only in tdb:///memdisk/autobuild/fl/b750545/samba-purepy3-ad-dc-2/bin/ab/restoredc/private/sam.ldb:
    CN=25862E9F-8BD4-4006-B94B-616036D24B0C,CN=NTDS SETTINGS,CN=RESTOREDC,CN=SERVERS,CN=DEFAULT-FIRST-SITE-NAME,CN=SITES,CN=CONFIGURATION,DC=BACKUPDOM,DC=SAMBA,DC=EXAMPLE,DC=COM

* Objects to be compared: 1618

* Result for [CONFIGURATION]: FAILURE

SUMMARY
---------

* Comparing [SCHEMA] context...

* Objects to be compared: 1550

* Result for [SCHEMA]: SUCCESS

* Comparing [DNSDOMAIN] context...

* Objects to be compared: 39

* Result for [DNSDOMAIN]: SUCCESS

* Comparing [DNSFOREST] context...

* Objects to be compared: 17

* Result for [DNSFOREST]: SUCCESS
ERROR: Compare failed: -1

FAILED (1 failures, 0 errors and 0 unexpected successes in 0 testsuites)

A summary with detailed information can be found in:
  ./bin/ab/summary
TOP 10 slowest tests
samba.tests.samba_tool.dnscmd(chgdcpass:local) -> 250
samba.tests.domain_backup(restoredc:local) -> 163
samba.tests.dcerpc.raw_protocol(chgdcpass) -> 48
samba4.blackbox.join_ldapcmp(backupfromdc) -> 15
samba4.blackbox.join_ldapcmp(offlinebackupdc) -> 14
samba4.net.api.become.dc(fl2000dc) -> 11
samba4.blackbox.kinit(fl2000dc:local)(fl2000dc:local) -> 10
samba.wbinfo_sids2xids.(chgdcpass:local)(chgdcpass:local) -> 9
samba4.blackbox.chgdcpass(chgdcpass) -> 7
samba4.rpc.pac on ncacn_np(fl2000dc) -> 7
ERROR: test failed with exit code 1