Code:  static int kvm_set_guest_paused(struct kvm_vcpu *vcpu)
 {
	if (!vcpu->arch.time_page)
 		return -EINVAL;
 	vcpu->arch.pvclock_set_guest_stopped_request = true;
 	kvm_make_request(KVM_REQ_CLOCK_UPDATE, vcpu);
	return 0;
}

Vulnerability Type: DoS Mem. Corr. 
CWE ID: CWE-399
Summary: Use-after-free vulnerability in arch/x86/kvm/x86.c in the Linux kernel through 3.8.4 allows guest OS users to cause a denial of service (host OS memory corruption) or possibly have unspecified other impact via a crafted application that triggers use of a guest physical address (GPA) in (1) movable or (2) removable memory during an MSR_KVM_SYSTEM_TIME kvm_set_msr_common operation.
Commit Message: KVM: x86: Convert MSR_KVM_SYSTEM_TIME to use gfn_to_hva_cache functions (CVE-2013-1797)

There is a potential use after free issue with the handling of
MSR_KVM_SYSTEM_TIME.  If the guest specifies a GPA in a movable or removable
memory such as frame buffers then KVM might continue to write to that
address even after it's removed via KVM_SET_USER_MEMORY_REGION.  KVM pins
the page in memory so it's unlikely to cause an issue, but if the user
space component re-purposes the memory previously used for the guest, then
the guest will be able to corrupt that memory.

Tested: Tested against kvmclock unit test

Signed-off-by: Andrew Honig <ahonig@google.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>