QEMU can create disk with size zero but can not format it or run it. Creation of zero size disk should be forbidden.
[root@dhcp-1-143 ~]# qemu-img create -f qcow2 test 0 Formatting 'test', fmt=qcow2, size=0 kB
[root@dhcp-1-143 ~]# qemu-img convert -f qcow2 test test2
qemu-img: Could not open 'test'
please provide kvm version
[root@magenta-vdsa ~]# rpm -qa | grep qemu
[root@magenta-vdsa ~]# rpm -qa | grep kvm
If anything, we should allow opening zero-sized images as in RHEL6. Patch would be trivial (removing check for header.size <= 1).
This request was evaluated by Red Hat Product Management for
inclusion in the current release of Red Hat Enterprise Linux.
Because the affected component is not scheduled to be updated in the
current release, Red Hat is unfortunately unable to address this
request at this time. Red Hat invites you to ask your support
representative to propose this request, if appropriate and relevant,
in the next release of Red Hat Enterprise Linux.
This request was erroneously denied for the current release of
Red Hat Enterprise Linux. The error has been fixed and this
request has been re-proposed for the current release.