Index: Lib/test/string_tests.py
===================================================================
--- Lib/test/string_tests.py	(revision 76951)
+++ Lib/test/string_tests.py	(working copy)
@@ -185,6 +185,9 @@
         self.checkequal(-1, '', 'find', 'xx', 1, 1)
         self.checkequal(-1, '', 'find', 'xx', sys.maxint, 0)
 
+        # issue 7458
+        self.checkequal(-1, 'ab', 'find', 'xxx', sys.maxsize + 1, 0)
+
         # For a variety of combinations,
         #    verify that str.find() matches __contains__
         #    and that the found substring is really at that location
@@ -230,6 +233,34 @@
         self.checkraises(TypeError, 'hello', 'rfind')
         self.checkraises(TypeError, 'hello', 'rfind', 42)
 
+        # issue 7458
+        self.checkequal(-1, 'ab', 'rfind', 'xxx', sys.maxsize + 1, 0)
+
+        # For a variety of combinations,
+        #    verify that str.rfind() matches __contains__
+        #    and that the found substring is really at that location
+        charset = ['', 'a', 'b', 'c']
+        digits = 5
+        base = len(charset)
+        teststrings = set()
+        for i in xrange(base ** digits):
+            entry = []
+            for j in xrange(digits):
+                i, m = divmod(i, base)
+                entry.append(charset[m])
+            teststrings.add(''.join(entry))
+        teststrings = list(teststrings)
+        for i in teststrings:
+            i = self.fixtype(i)
+            for j in teststrings:
+                loc = i.rfind(j)
+                r1 = (loc != -1)
+                r2 = j in i
+                if r1 != r2:
+                    self.assertEqual(r1, r2)
+                if loc != -1:
+                    self.assertEqual(i[loc:loc+len(j)], j)
+
     def test_index(self):
         self.checkequal(0, 'abcdefghiabc', 'index', '')
         self.checkequal(3, 'abcdefghiabc', 'index', 'def')
@@ -686,8 +717,10 @@
         EQ("bobobXbobob", "bobobobXbobobob", "replace", "bobob", "bob")
         EQ("BOBOBOB", "BOBOBOB", "replace", "bob", "bobby")
 
-        ba = buffer('a')
-        bb = buffer('b')
+        # Silence Py3k warning
+        with test_support.check_warnings():
+            ba = buffer('a')
+            bb = buffer('b')
         EQ("bbc", "abc", "replace", ba, bb)
         EQ("aac", "abc", "replace", bb, ba)
 
Index: Lib/test/test_unicode.py
===================================================================
--- Lib/test/test_unicode.py	(revision 76951)
+++ Lib/test/test_unicode.py	(working copy)
@@ -499,9 +499,12 @@
         )
 
         if not sys.platform.startswith('java'):
+            # Silence Py3k warning
+            with test_support.check_warnings():
+                buf = buffer('character buffers are decoded to unicode')
             self.assertEqual(
                 unicode(
-                    buffer('character buffers are decoded to unicode'),
+                    buf,
                     'utf-8',
                     'strict'
                 ),