CVE-2017-12154 Kernel: kvm: nVMX: L2 guest could access hardware(L0) CR8 register

[P J P <ppandit () redhat com>]

  Hello,

Linux kernel built with the KVM virtualisation support(CONFIG_KVM), with 
nested virtualisation(nVMX) feature enabled(nested=1), is vulnerable to a 
crash due to disabled external interrupts. As L2 guest could access(r/w) 
hardware CR8 register of the host(L0).

In a nested virtualisation setup, L2 guest user could use this flaw to 
potentially crash the host(L0) resulting in DoS.

Upstream patch
--------------
  -> https://git.kernel.org/linus/51aa68e7d57e3217192d88ce90fd5b8ef29ec94f

This issue was reported by Jim Mattson of Google.com.

Thank you.
--
Prasad J Pandit / Red Hat Product Security Team
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