> @haypo: Python 2.7 is absolute horror.

Oh, zlib doesn't use PY_SSIZE_T_CLEAN in Python 2.7.

11277-27.1.diff contains "# Issue #10276 - check that inputs >=4GB are handled correctly.". I don't understand this comment because the test uses a buffer of 2 GB + 2 bytes.

How is it possible to pass a buffer of 2 GB+2 bytes to crc32(), whereas it stores the size into an int. The maximum size is INT_MAX which is 2 GB-1 byte. It looks like the "i" format of PyArg_ParseTuple() doesn't check for integer overflow => issue #8651. This issue was fixed in 3.1, 3.2 and 3.3, but not in Python 2.

Should we fix Python 2.7?
 - backport issue #8651
 - use PY_SSIZE_T_CLEAN in zlibmodule.c