Vigil@nce: Linux kernel, denial of service via EFER
April 2009 by Vigil@nce
On an x86 virtualized computer, a local attacker can use EFER to stop the system.
Consequences: denial of service of computer
Provenance: user shell
Means of attack: no proof of concept, no attack
Ability of attacker: expert (4/4)
Confidence: confirmed by the editor (5/5)
Diffusion of the vulnerable configuration: high (3/3)
Creation date: 01/04/2009
DESCRIPTION OF THE VULNERABILITY
An x86 processor supports VMX (Virtual Machine Extensions).
The vmx_set_msr() function of the arch/x86/kvm/vmx.c file sets MSR
(Model Specific Registers):
MSR_EFER : extended feature
MSR_STAR : legacy mode syscall target
The EFER MSR is specific to x64 processors. However, in a i386 virtual machine, the vmx_set_msr() function tries to set it, which panics the kernel.
On an x86 virtualized computer, a local attacker can therefore use EFER to stop the system.