set_debugreg allows writes to reserved bits of the DR7 debug control register on x86-64.
A malicious guest can cause the host to crash, leading to a DoS.
If the vulnerable hypervisor is run on future hardware, the impact of the vulnerability might be widened depending on the future assignment of the currently-reserved debug register bits.
All systems running 64-bit paravirtualised guests are vulnerable to this issue.
Red Hat would like to thank the Xen project for reporting this issue.
This issue did not affect the versions of the kernel-xen package as shipped with Red Hat Enterprise Linux 5.
This issue did not affect Red Hat Enterprise Linux 6 and Red Hat Enterprise MRG as we did not have support for Xen hypervisor.
Now public via:
Created xen tracking bugs for this issue
Affects: fedora-all [bug 854585]
xen-4.1.3-2.fc16 has been pushed to the Fedora 16 stable repository. If problems still persist, please make note of it in this bug report.