buffers: fix crash

this change is being made to fix a crash when current_data < 0 in buffer
linearization function

Ticket: N/A
Type: fix
Fixes: f883f6a113

Change-Id: Ia4ede823f673780e0c30d075b091db42e183650d
Signed-off-by: Klement Sekera <ksekera@cisco.com>

test/test_buffers.py

@@ -0,0 +1,29 @@
+#!/usr/bin/env python
+
+from framework import VppTestCase
+
+
+class TestBuffers(VppTestCase):
+    """ Buffer C Unit Tests """
+
+    @classmethod
+    def setUpClass(cls):
+        super(TestBuffers, cls).setUpClass()
+
+    @classmethod
+    def tearDownClass(cls):
+        super(TestBuffers, cls).tearDownClass()
+
+    def setUp(self):
+        super(TestBuffers, self).setUp()
+
+    def tearDown(self):
+        super(TestBuffers, self).tearDown()
+
+    def test_linearize(self):
+        """ Chained Buffer Linearization """
+        error = self.vapi.cli("test chained-buffer-linearization")
+
+        if error:
+            self.logger.critical(error)
+            self.assertNotIn('failed', error)