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Andrew Bartlett 004e7a1fee s4/rpc_server/dnsserver: Allow parsing of dnsProperty to fail gracefully
On (eg) the

DC=_msdcs.X.Y,CN=MicrosoftDNS,DC=ForestDnsZones,DC=X,DC=Y

record, in domains that have had a Microsoft Windows DC an attribute:

dNSProperty:: AAAAAAAAAAAAAAAAAQAAAJIAAAAAAAAA

000000 00 00 00 00 00 00 00 00 00 00 00 00 01 00 00 00  >................<
000010 92 00 00 00 00 00 00 00                          >........<
000018

We, until samba 4.12, would parse this as:

pull returned Success
    dnsp_DnsProperty: struct dnsp_DnsProperty
        wDataLength              : 0x00000000 (0)
        namelength               : 0x00000000 (0)
        flag                     : 0x00000000 (0)
        version                  : 0x00000001 (1)
        id                       : DSPROPERTY_ZONE_NS_SERVERS_DA (146)
        data                     : union dnsPropertyData(case 0)
        name                     : 0x00000000 (0)
dump OK

However, the wDataLength is 0.  There is not anything in
[MS-DNSP] 2.3.2.1 dnsProperty to describe any special behaviour
for when the id suggests that there is a value, but wDataLength is 0.

https://docs.microsoft.com/en-us/openspecs/windows_protocols/ms-dnsp/445c7843-e4a1-4222-8c0f-630c230a4c80

We now fail to parse it, because we expect an entry with id DSPROPERTY_ZONE_NS_SERVERS_DA
to therefore have a valid DNS_ADDR_ARRAY (section 2.2.3.2.3).

As context we changed it in our commit fee5c6a4247aeac71318186bbff7708d25de5912
because of bug https://bugzilla.samba.org/show_bug.cgi?id=14206
which was due to the artificial environment of the fuzzer.

Microsoft advises that Windows also fails to parse this, but
instead of failing the operation, the value is ignored.

Reported by Alex MacCuish.  Many thanks for your assistance in
tracking down the issue.

BUG: https://bugzilla.samba.org/show_bug.cgi?id=14310

Signed-off-by: Andrew Bartlett <abartlet@samba.org>
Reviewed-by: Douglas Bagnall <douglas.bagnall@catalyst.net.nz>

Autobuild-User(master): Andrew Bartlett <abartlet@samba.org>
Autobuild-Date(master): Fri May 15 07:29:17 UTC 2020 on sn-devel-184
2020-05-15 07:29:16 +00:00
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2018-07-12 04:31:56 +02:00
2013-07-29 09:12:17 +02:00