The MITRE CVE dictionary describes this issue as:
The kvm_vm_ioctl_assign_device function in virt/kvm/assigned-dev.c in the KVM subsystem in the Linux kernel before 3.1.10 does not verify permission to access PCI configuration space and BAR resources, which allows host OS users to assign PCI devices and cause a denial of service (host OS crash) via a KVM_ASSIGN_PCI_DEVICE operation.
Find out more about CVE-2011-4347 from the
MITRE CVE dictionary dictionary and
This issue did not affect the versions of Linux kernel as shipped with Red Hat Enterprise Linux 4 and Red Hat Enterprise MRG as they did not provide support for the KVM subsystem. This has been addressed in Red Hat Enterprise Linux 6 via https://rhn.redhat.com/errata/RHSA-2012-0350.html. A future kvm update in Red Hat Enterprise 5 may address this flaw.