From 11034ea33fca9b8a1c2e14480e70069b55fca6a2 Mon Sep 17 00:00:00 2001 From: Andrew Bartlett Date: Thu, 25 Jun 2020 11:59:54 +1200 Subject: CVE-2020-14303 Ensure an empty packet will not DoS the NBT server Signed-off-by: Andrew Bartlett --- python/samba/tests/dns_packet.py | 19 +++++++++++++++++++ selftest/knownfail.d/empty-nbt | 1 + 2 files changed, 20 insertions(+) create mode 100644 selftest/knownfail.d/empty-nbt diff --git a/python/samba/tests/dns_packet.py b/python/samba/tests/dns_packet.py index c4f843eb613..ae7bcb3ad8c 100644 --- a/python/samba/tests/dns_packet.py +++ b/python/samba/tests/dns_packet.py @@ -156,6 +156,19 @@ class TestDnsPacketBase(TestCase): rcode = self.decode_reply(data)['rcode'] return expected_rcode == rcode + def _test_empty_packet(self): + + packet = b"" + s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM) + s.sendto(packet, self.server) + s.close() + + # It is reasonable not to reply to an empty packet + # but it is not reasonable to render the server + # unresponsive. + ok = self._known_good_query() + self.assertTrue(ok, f"the server is unresponsive") + class TestDnsPackets(TestDnsPacketBase): server = (SERVER, 53) @@ -174,6 +187,9 @@ class TestDnsPackets(TestDnsPacketBase): label = b'x.' * 31 + b'x' self._test_many_repeated_components(label, 127) + def test_empty_packet(self): + self._test_empty_packet() + class TestNbtPackets(TestDnsPacketBase): server = (SERVER, 137) @@ -209,3 +225,6 @@ class TestNbtPackets(TestDnsPacketBase): def test_127_half_dotty_components(self): label = b'x.' * 31 + b'x' self._test_many_repeated_components(label, 127) + + def test_empty_packet(self): + self._test_empty_packet() diff --git a/selftest/knownfail.d/empty-nbt b/selftest/knownfail.d/empty-nbt new file mode 100644 index 00000000000..e4bcccab4e5 --- /dev/null +++ b/selftest/knownfail.d/empty-nbt @@ -0,0 +1 @@ +^samba.tests.dns_packet.samba.tests.dns_packet.TestNbtPackets.test_empty_packet \ No newline at end of file -- cgit v1.2.1