Vigil@nce - Linux kernel: denial of service via KVM
October 2014 by Vigil@nce
This bulletin was written by Vigil@nce : http://vigilance.fr/offer
SYNTHESIS OF THE VULNERABILITY
An attacker can open the control device /dev/kvm while a guest
system uses the privileged register CR4, in order to trigger a
denial of service.
Impacted products: Linux
Severity: 1/4
Creation date: 22/10/2014
DESCRIPTION OF THE VULNERABILITY
The Linux kernel support the functions and instructions of Intel
x86 and x86_64 processors dedicated to assisted virtualization.
When the virtualization control tool is QEMU+KVM, the special file
/dev/kvm allows to send commands to the host kernel from a user
process running in the host. However, when the CR4 register of the
processor of the virtual machine is changed between two VM entries
and /dev/kvm is opened, the host kernel enters in an invalid state
and crashes.
An attacker can therefore open the control device /dev/kvm while a
guest system uses the privileged register CR4, in order to trigger
a denial of service.
ACCESS TO THE COMPLETE VIGIL@NCE BULLETIN
http://vigilance.fr/vulnerability/Linux-kernel-denial-of-service-via-KVM-15517