Description: ashmem readonly bypasses via remap_file_pages() and ASHMEM_UNPIN
References:
 https://bugs.chromium.org/p/project-zero/issues/detail?id=1949
Notes:
 jmm> Just staging
Bugs:
upstream: released (5.6-rc3) [6d67b0290b4b84c477e6a2fc6e005e174d3c7786]
4.19-upstream-stable: released (4.19.107) [a4307700608e43dcf9b8abf1ee74f68227e9c61a]
4.9-upstream-stable: released (4.9.215) [a7fc5dbd17127c7301b0aefc2bcf1f54169c7383]
3.16-upstream-stable: released (3.16.83) [85216b0a3fc5f3eb08e68750175f8507d5608e37]
sid: released (5.5.13-1)
4.19-buster-security: released (4.19.118-1)
4.9-stretch-security: released (4.9.228-1)
3.16-jessie-security: released (3.16.84-1)