[Samba] possible memory leak in ldb module while dbcheck on RODC

[L.P.H. van Belle]

What is the ldb version your using? 
You need : 1.1.29 with samba 4.5.7. 

Greetz, 

Louis


> -----Oorspronkelijk bericht-----
> Van: samba [mailto:samba-bounces at lists.samba.org] Namens Andrej Gessel via
> samba
> Verzonden: vrijdag 31 maart 2017 8:55
> Aan: samba at lists.samba.org
> Onderwerp: Re: [Samba] possible memory leak in ldb module while dbcheck on
> RODC
> 
> Hello,
> 
> my message was not send with my attachment, because content-type was not
> allowed,  sorry for that.
> 
> i am trying to use Samba 4.5.7 as an RODC and maybe found a memory leak in
> ldb module.
> 
> There is an known BUG https://bugzilla.samba.org/show_bug.cgi?id=11178 and
> a known fix in dbcheck.
> 
> If i run "samba-tool dbcheck --cross-ncs --fix", this running process
> starts with ~300MB and use at the end about 1,6GB of memory on test domain
> with 15000 users and 15000 groups(ntds.dit is only ~150MB). I tried to
> find out why it is increasing continuously.
> 
> 
> 1) I used memory_profiler and modified dbchecker.py:
> 
> root at buildhost samba # git diff dbchecker.py
> diff --git a/dbchecker.py b/dbchecker.py
> index 032c0e7..6fe0d4d 100644
> --- a/dbchecker.py
> +++ b/dbchecker.py
> @@ -17,6 +17,7 @@
> # along with this program.  If not, see <http://www.gnu.org/licenses/>.
> #
> 
> +from memory_profiler import profile
> import ldb
> import samba
> import time
> @@ -356,6 +357,7 @@ systemFlags: -1946157056%s""" % (dn, guid_suffix),
>              return False
>          return True
> 
> +    @profile
>      def do_modify(self, m, controls, msg, validate=True):
>          '''perform a modify with optional verbose output'''
>          if self.verbose:
> @@ -751,6 +753,7 @@ newSuperior: %s""" % (str(from_dn), str(to_rdn),
> str(to_base)))
>                            "Failed to rename object %s into %s" % (obj.dn,
> new_dn)):
>              self.report("Renamed %s into %s" % (obj.dn, new_dn))
> 
> +    @profile
>      def err_wrong_instancetype(self, obj, calculated_instancetype):
>          '''handle a wrong instanceType'''
>          self.report("ERROR: wrong instanceType %s on %s, should be %d" %
> (obj["instanceType"], obj.dn, calculated_instancetype))
> @@ -1541,6 +1544,7 @@ newSuperior: %s""" % (str(from_dn), str(to_rdn),
> str(to_base)))
> 
>          raise KeyError
> 
> +    @profile(precision=4)
>      def check_object(self, dn, attrs=['*']):
>          '''check one object'''
>          if self.verbose:
> 
> Output of memory_profiler shows me additional ~2MB of memory usage after
> every run of check_object function (show memory_profiler.txt for details
> partial, because of mailing list limits).
> 
> 2) After i comment out the line in dbchecker.py, memory is not increasing
> anymore.
> 
> @@ -356,13 +357,14 @@ systemFlags: -1946157056%s""" % (dn, guid_suffix),
>              return False
>          return True
> 
> +    @profile
>      def do_modify(self, m, controls, msg, validate=True):
>          '''perform a modify with optional verbose output'''
>          if self.verbose:
>              self.report(self.samdb.write_ldif(m, ldb.CHANGETYPE_MODIFY))
>          try:
>              controls = controls + ["local_oid:%s:0" %
> dsdb.DSDB_CONTROL_DBCHECK]
> -            self.samdb.modify(m, controls=controls, validate=validate)
> +#            self.samdb.modify(m, controls=controls, validate=validate)
>          except Exception, err:
>             if self.in_transaction:
>                  raise CommandError("%s : %s" % (msg, err))
> 
> 
> 
> 3) My first idea was that it is python problem with starting c modules,
> but then i found pyldb.c and py_ldb_modify function in it. Commenting out
> the line with ldb_request memory stays on the same value and does not
> increase anymore.
> 
> root at buildhost samba (git)-[samba-4.5.7] # git diff lib/ldb/pyldb.c
> diff --git a/lib/ldb/pyldb.c b/lib/ldb/pyldb.c
> index bea837f..ed5309a 100644
> --- a/lib/ldb/pyldb.c
> +++ b/lib/ldb/pyldb.c
> @@ -1255,7 +1255,7 @@ static PyObject *py_ldb_modify(PyLdbObject *self,
> PyObject *args, PyObject *kwar
>                 return NULL;
>         }
> 
> -       ret = ldb_request(ldb_ctx, req);
> +       //ret = ldb_request(ldb_ctx, req);
>         if (ret == LDB_SUCCESS) {
>                 ret = ldb_wait(req->handle, LDB_WAIT_ALL);
>         }
> 
> 
> 
> So now to my question:
> Is it really a bug or does ldb library do something, that i did not
> see/understand till now?
> 
> 
> regards,
> 
> Andrej
> 
> Von: samba [mailto:samba-bounces at lists.samba.org] Im Auftrag von Andrej
> Gessel via samba
> Gesendet: Donnerstag, 30. März 2017 23:33
> An: samba at lists.samba.org
> Betreff: [Samba] possible memory leak in ldb module while dbcheck on RODC
> 
> 
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