diff -r 038dd5e1f01b Lib/test/test_re.py
--- a/Lib/test/test_re.py	Sat Feb 04 14:59:11 2017 +0100
+++ b/Lib/test/test_re.py	Sat Feb 04 19:30:27 2017 +0300
@@ -1821,6 +1821,13 @@
             warnings.simplefilter('error', BytesWarning)
             self.assertNotEqual(pattern3, pattern1)
 
+    def test_bug_29444(self):
+        pattern = b'A*'
+        s = bytearray(b'A' * 100)
+        m = re.search(pattern, s)
+        del s[:]
+        self.assertEqual(m.group(), b'')
+
 
 class PatternReprTests(unittest.TestCase):
     def check(self, pattern, expected):
diff -r 038dd5e1f01b Modules/_sre.c
--- a/Modules/_sre.c	Sat Feb 04 14:59:11 2017 +0100
+++ b/Modules/_sre.c	Sat Feb 04 19:30:27 2017 +0300
@@ -1945,6 +1945,7 @@
     Py_buffer view;
     PyObject *result;
     void* ptr;
+    Py_ssize_t i, j;
 
     if (index < 0 || index >= self->groups) {
         /* raise IndexError if we were given a bad group number */
@@ -1966,8 +1967,14 @@
     ptr = getstring(self->string, &length, &isbytes, &charsize, &view);
     if (ptr == NULL)
         return NULL;
+
+    i = self->mark[index];
+    j = self->mark[index+1];
+    
+    PySlice_AdjustIndices(length, &i, &j, 1);
+
     result = getslice(isbytes, ptr,
-                      self->string, self->mark[index], self->mark[index+1]);
+                      self->string, i, j);
     if (isbytes && view.buf != NULL)
         PyBuffer_Release(&view);
     return result;