[Samba] issue when upgrading to latest security release 4.14.10 when having multiple consecutive space in DN

[Denis CARDON]

Hi everyone,

we have had this issue a few time today with latest 4.14 when upgrading 
client installations, so I thought it might be of interest for some of 
you all (I didn't have time to check if it was latest 4.14.10 or if it 
happened in some earlier version).

If you have DN strings with consecutive space characters (yeah, it 
shouldn't happen, but if one can do it, it will be done), then the 
upgrade will break a few things.

In the replication you'll get this kind of error message :

[2021/11/10 15:15:33.150632,  1] 
../../source4/dsdb/repl/replicated_objects.c:904(dsdb_replicated_objects_commit)
   Failed to apply records: operational_search_post_process failed for 
attribute 'parentGUID' - No such Base DN: CN=USERNAME  Romain,OU=Sync 
Azure,DC=mydomain,DC=lan: Operations error
[2021/11/10 15:15:33.150754,  0] 
../../source4/dsdb/repl/drepl_out_helpers.c:1184(dreplsrv_op_pull_source_apply_changes_trigger)

If you try a samba-tool dbcheck --cross-ncs, you'll may get this kind of 
error :

ERROR: Object CN=USERNAME  Romain,OU=Sync Azure,DC=mydomain,DC=lan 
disappeared during check

Another symptom is that the search with an attribute (like samba-tool 
user show dcardon) does work, but a ldbsearch with a DN like below 
(beware of the two spaces) does not work
'CN=denis  cardon,OU=test,DC=test,DC=lan'

If you have this case, a reindex should fix it (it need to be run on 
each DC)
samba-tool dbcheck --reindex

Another option is to fix this before upgrade, or if it is already 
upgraded, downgrade, fix and then upgrade.

If you have the case where you have two quasi-identical entries, one 
with two space and one with only one (ie CN=denis cardon, and CN=denis 
cardon), then you have to delete one of them before re-indexing (yeah we 
have seen this one today also).

There seems to be a discrepancy in the way multiple spaces are handled 
in the index and in the DN string itself.

Note : if you recreate an entry with multiple consecutive spaces after 
upgrade it seems to work though...

Happy upgrading, cheers to the Samba team for all the great work, and 
happy holiday for everyone here in France!

Denis