CVE-2014-0222 Qemu: qcow1: Validate L2 table size

[P J P <ppandit () redhat com>]

  Hello,

'CVE-2014-0222' has been assigned to this issue.

Too large L2 table sizes cause unbounded allocations. Images actually
created by qemu-img only have 512 byte or 4k L2 tables.

To keep things consistent with cluster sizes, allow ranges between 512
bytes and 64k (in fact, down to 1 entry = 8 bytes is technically
working, but L2 table sizes smaller than a cluster don't make a lot of
sense).

This also means that the number of bytes on the virtual disk that are
described by the same L2 table is limited to at most 8k * 64k or 2^29,
preventively avoiding any integer overflows.

Upstream fix:
-------------
  -> https://lists.gnu.org/archive/html/qemu-devel/2014-05/msg02155.html

Thank you.
--
Prasad J Pandit / Red Hat Security Response Team