Race condition in workers may cause an exploitable double free by abusing bytearray.compress()

How it was found

The issue occurs while sharing a bytearray between two workers. If one worker calls bytearray.compress() while the other uses that bytearray, Flash does not correctly handle the race and may double free the array.

Identified as CVE-2015-0312, and reported to Adobe via Chrome VRP: https://helpx.adobe.com/security/products/flash-player/apsb15-03.html

Original report with exploit for Chrome: https://code.google.com/p/chromium/issues/detail?id=436022