- Issue #5104: The socket module now raises OverflowError when 16-bit port and

protocol numbers are supplied outside the allowed 0-65536 range on bind()
  and getservbyport().

Lib/test/test_socket.py

@@ -356,6 +356,9 @@ class GeneralModuleTests(unittest.TestCase):
         eq(socket.getservbyport(port, 'tcp'), service)
         if udpport is not None:
             eq(socket.getservbyport(udpport, 'udp'), service)
+        # Make sure getservbyport does not accept out of range ports.
+        self.assertRaises(OverflowError, socket.getservbyport, -1)
+        self.assertRaises(OverflowError, socket.getservbyport, 65536)
 
     def testDefaultTimeout(self):
         # Testing default timeout
@@ -456,15 +459,23 @@ class GeneralModuleTests(unittest.TestCase):
 
     # XXX The following don't test module-level functionality...
 
-    def testSockName(self):
+    def _get_unused_port(self, bind_address='0.0.0.0'):
-        # Testing getsockname().  Use a temporary socket to elicit an unused
+        """Use a temporary socket to elicit an unused ephemeral port.
-        # ephemeral port that we can use later in the test.
-        tempsock = socket.socket()
-        tempsock.bind(("0.0.0.0", 0))
-        (host, port) = tempsock.getsockname()
-        tempsock.close()
-        del tempsock
 
+        Args:
+            bind_address: Hostname or IP address to search for a port on.
+
+        Returns: A most likely to be unused port.
+        """
+        tempsock = socket.socket()
+        tempsock.bind((bind_address, 0))
+        host, port = tempsock.getsockname()
+        tempsock.close()
+        return port
+
+    def testSockName(self):
+        # Testing getsockname()
+        port = self._get_unused_port()
         sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
         sock.bind(("0.0.0.0", port))
         name = sock.getsockname()
@@ -504,6 +515,19 @@ class GeneralModuleTests(unittest.TestCase):
         self.assertEqual(sock.proto, 0)
         sock.close()
 
+    def test_getsockaddrarg(self):
+        host = '0.0.0.0'
+        port = self._get_unused_port(bind_address=host)
+        big_port = port + 65536
+        neg_port = port - 65536
+        sock = socket.socket()
+        try:
+            self.assertRaises(OverflowError, sock.bind, (host, big_port))
+            self.assertRaises(OverflowError, sock.bind, (host, neg_port))
+            sock.bind((host, port))
+        finally:
+            sock.close()
+
     def test_sock_ioctl(self):
         if os.name != "nt":
             return

Misc/NEWS

@@ -383,6 +383,10 @@ Library
 - Issue #4861: ctypes.util.find_library(): Robustify. Fix library detection on
   biarch systems. Try to rely on ldconfig only, without using objdump and gcc.
 
+- Issue #5104: The socket module now raises OverflowError when 16-bit port and
+  protocol numbers are supplied outside the allowed 0-65536 range on bind()
+  and getservbyport().
+
 Tools/Demos
 -----------
 

Modules/socketmodule.c

@@ -1259,6 +1259,12 @@ getsockaddrarg(PySocketSockObject *s, PyObject *args,
                 PyMem_Free(host);
                 if (result < 0)
 			return 0;
+		if (port < 0 || port > 0xffff) {
+			PyErr_SetString(
+				PyExc_OverflowError,
+				"getsockaddrarg: port must be 0-65535.");
+			return 0;
+		}
 		addr->sin_family = AF_INET;
 		addr->sin_port = htons((short)port);
 		*len_ret = sizeof *addr;
@@ -1291,6 +1297,12 @@ getsockaddrarg(PySocketSockObject *s, PyObject *args,
                 PyMem_Free(host);
                 if (result < 0)
 			return 0;
+		if (port < 0 || port > 0xffff) {
+			PyErr_SetString(
+				PyExc_OverflowError,
+				"getsockaddrarg: port must be 0-65535.");
+			return 0;
+		}
 		addr->sin6_family = s->sock_family;
 		addr->sin6_port = htons((short)port);
 		addr->sin6_flowinfo = flowinfo;
@@ -1417,6 +1429,12 @@ getsockaddrarg(PySocketSockObject *s, PyObject *args,
 				  "Hardware address must be 8 bytes or less");
 		  return 0;
 		}
+		if (protoNumber < 0 || protoNumber > 0xffff) {
+			PyErr_SetString(
+				PyExc_OverflowError,
+				"getsockaddrarg: protoNumber must be 0-65535.");
+			return 0;
+		}
 		addr = (struct sockaddr_ll*)addr_ret;
 		addr->sll_family = AF_PACKET;
 		addr->sll_protocol = htons((short)protoNumber);
@@ -3446,13 +3464,19 @@ otherwise any protocol will match.");
 static PyObject *
 socket_getservbyport(PyObject *self, PyObject *args)
 {
-	unsigned short port;
+	int port;
 	char *proto=NULL;
 	struct servent *sp;
-	if (!PyArg_ParseTuple(args, "H|s:getservbyport", &port, &proto))
+	if (!PyArg_ParseTuple(args, "i|s:getservbyport", &port, &proto))
 		return NULL;
+	if (port < 0 || port > 0xffff) {
+		PyErr_SetString(
+			PyExc_OverflowError,
+			"getservbyport: port must be 0-65535.");
+		return NULL;
+	}
 	Py_BEGIN_ALLOW_THREADS
-	sp = getservbyport(htons(port), proto);
+	sp = getservbyport(htons((short)port), proto);
 	Py_END_ALLOW_THREADS
 	if (sp == NULL) {
 		PyErr_SetString(socket_error, "port/proto not found");