Qemu before 2.0 block driver for Hyper-V VHDX Images is vulnerable to infinite loops and other potential issues when calculating BAT entries, due to missing bounds checks for block_size and logical_sector_size variables. These are used to derive other fields like 'sectors_per_block' etc. A user able to alter the Qemu disk image could ise this flaw to crash the Qemu instance resulting in DoS.
http://rhn.redhat.com/errata/RHSA-2014-0420.html
http://rhn.redhat.com/errata/RHSA-2014-0421.html
https://bugzilla.redhat.com/show_bug.cgi?id=1078212
https://lists.gnu.org/archive/html/qemu-devel/2014-03/msg04994.html