qemu: Security fix CVE-2016-4952

qemu: Security fix CVE-2016-4952

affects qemu < 2.7.0

Quick Emulator(Qemu) built with the VMWARE PVSCSI paravirtual SCSI bus
emulation support is vulnerable to an OOB r/w access issue. It could
occur while processing SCSI commands 'PVSCSI_CMD_SETUP_RINGS' or
'PVSCSI_CMD_SETUP_MSG_RING'.

A privileged user inside guest could use this flaw to crash the Qemu
process resulting in DoS.

References:
----------
http://www.openwall.com/lists/oss-security/2016/05/23/1

Signed-off-by: Adrian Dudau <adrian.dudau@enea.com>
Signed-off-by: Armin Kuster <akuster808@gmail.com>