[Samba] ERROR: pad length mismatch. Calculated 44 got 0

[mj]

Hi,

Searching my samba logs for errors, I noticed the following logged 
occasionally on (all three) DCs:

> ../../librpc/rpc/dcerpc_util.c:373: ERROR: pad length mismatch. Calculated 44  got 0

Searching the samba archives, they seem to be related to DNS.

So I checked our config. We're on buster, with:

> root at dc2:~# dpkg -l | grep bind9
> ii  bind9                            1:9.11.5.P4+dfsg-5.1+deb10u2 amd64        Internet Domain Name Server
> ii  bind9-host                       1:9.11.5.P4+dfsg-5.1+deb10u2 amd64        DNS lookup utility (deprecated)
> ii  bind9utils                       1:9.11.5.P4+dfsg-5.1+deb10u2 amd64        Utilities for BIND
> ii  libbind9-161:amd64               1:9.11.5.P4+dfsg-5.1+deb10u2 amd64        BIND9 Shared Library used by BIND

(output similar for DC3 & DC4)

And:

> root at dc2:~# cat /var/lib/samba/private/named.conf
> # This DNS configuration is for BIND 9.8.0 or later with dlz_dlopen support.
> #
> # This file should be included in your main BIND configuration file
> #
> # For example with
> # include "/var/lib/samba/private/named.conf";
> 
> #
> # This configures dynamically loadable zones (DLZ) from AD schema
> # Uncomment only single database line, depending on your BIND version
> #
> dlz "AD DNS Zone" {
>     # For BIND 9.8.x
>     # database "dlopen /usr/lib/x86_64-linux-gnu/samba/bind9/dlz_bind9.so";
> 
>     # For BIND 9.9.x
>     # database "dlopen /usr/lib/x86_64-linux-gnu/samba/bind9/dlz_bind9_9.so";
> 
>     # For BIND 9.10.x
>     # database "dlopen /usr/lib/x86_64-linux-gnu/samba/bind9/dlz_bind9_10.so";
> 
>     # For BIND 9.11.x
>     database "dlopen /usr/lib/x86_64-linux-gnu/samba/bind9/dlz_bind9_11.so";
> };
(output again similar for DC3 & DC4)

And bind seems to be running fine:

> root at dc2:~# service bind9 status
> ● bind9.service - BIND Domain Name Server
>    Loaded: loaded (/lib/systemd/system/bind9.service; enabled; vendor preset: enabled)
>    Active: active (running) since Tue 2020-11-17 20:43:15 CET; 1 weeks 0 days ago
>      Docs: man:named(8)
>   Process: 403 ExecStart=/usr/sbin/named $OPTIONS (code=exited, status=0/SUCCESS)
>  Main PID: 439 (named)
>     Tasks: 7 (limit: 4700)
>    Memory: 68.1M
>    CGroup: /system.slice/bind9.service
>            └─439 /usr/sbin/named -u bind
> 
> Nov 25 10:05:22 dc2 named[439]: samba_dlz: starting transaction on zone samba.company.com
> Nov 25 10:05:22 dc2 named[439]: samba_dlz: allowing update of signer=PATSTAT-WIN2016\$\@samba.company.com name=patstat-win2016.samba.company.com tcpaddr=1.2.3.48 type=AAAA key=1080-ms-7.269-b24d64f4.031a354c-c5b1-11ea-bb9b-ac1f6b
> Nov 25 10:05:22 dc2 named[439]: samba_dlz: allowing update of signer=PATSTAT-WIN2016\$\@samba.company.com name=patstat-win2016.samba.company.com tcpaddr=1.2.3.48 type=A key=1080-ms-7.269-b24d64f4.031a354c-c5b1-11ea-bb9b-ac1f6b7af
> Nov 25 10:05:22 dc2 named[439]: samba_dlz: allowing update of signer=PATSTAT-WIN2016\$\@samba.company.com name=patstat-win2016.samba.company.com tcpaddr=1.2.3.48 type=A key=1080-ms-7.269-b24d64f4.031a354c-c5b1-11ea-bb9b-ac1f6b7af
> Nov 25 10:05:22 dc2 named[439]: client @0x7f009011deb0 1.2.3.48#52868/key PATSTAT-WIN2016\$\@samba.company.com: updating zone 'samba.company.com/NONE': deleting rrset at 'patstat-win2016.samba.company.com' AAAA
> Nov 25 10:05:22 dc2 named[439]: client @0x7f009011deb0 1.2.3.48#52868/key PATSTAT-WIN2016\$\@samba.company.com: updating zone 'samba.company.com/NONE': deleting rrset at 'patstat-win2016.samba.company.com' A
> Nov 25 10:05:22 dc2 named[439]: samba_dlz: subtracted rdataset patstat-win2016.samba.company.com 'patstat-win2016.samba.company.com.        1200        IN        A        1.2.3.48'
> Nov 25 10:05:22 dc2 named[439]: client @0x7f009011deb0 1.2.3.48#52868/key PATSTAT-WIN2016\$\@samba.company.com: updating zone 'samba.company.com/NONE': adding an RR at 'patstat-win2016.samba.company.com' A 1.2.3.48
> Nov 25 10:05:22 dc2 named[439]: samba_dlz: added rdataset patstat-win2016.samba.company.com 'patstat-win2016.samba.company.com.        1200        IN        A        1.2.3.48'
> Nov 25 10:05:22 dc2 named[439]: samba_dlz: committed transaction on zone samba.company.com

However, over the last 24 hours, we had 41 messages "ERROR: pad length 
mismatch. Calculated 44  got 0" across all DCs.

As everything is basically running fine, I'm not too worried about them, 
but before I look into this more:

Others here observe the same?

MJ