Closes release blocker #3627.

Merged revisions 65335 via svnmerge from
svn+ssh://pythondev@svn.python.org/python/trunk

TESTED=./python -E -tt ./Lib/test/regrtest.py -uall (both debug and opt)

........
  r65335 | neal.norwitz | 2008-07-31 10:17:14 -0700 (Thu, 31 Jul 2008) | 1 line

  Security patches from Apple:  prevent int overflow when allocating memory
........
diff --git a/Modules/mmapmodule.c b/Modules/mmapmodule.c
index 8abf0ff..9adef9b 100644
--- a/Modules/mmapmodule.c
+++ b/Modules/mmapmodule.c
@@ -245,7 +245,7 @@
 		return(NULL);
 
 	/* silently 'adjust' out-of-range requests */
-	if ((self->pos + num_bytes) > self->size) {
+	if (num_bytes > self->size - self->pos) {
 		num_bytes -= (self->pos+num_bytes) - self->size;
 	}
 	result = PyByteArray_FromStringAndSize(self->data+self->pos, num_bytes);