On Tue, Apr 2, 2013 at 11:05 PM, Florian Beck wrote:
> The CVE-2013-1796
> (https://git.kernel.org/cgit/virt/kvm/kvm.git/commit/?id=c300aa64ddf57d9c5d9c898a64b36877345dd4a9)
> reports a possibility of host memory corruption.
> I see that this could lead into corruption of guest kernel memory,
> but how could be the wrong aligned address reported by guest corrupt
> host kernel memory?
If the region crosses a page boundary.
>
>
> Regards, Florian
>
> --
> This was the posted fix for CVE-2013-1796:
> --
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index f7c850b..2ade60c 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -1959,6 +1959,11 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu,
> struct msr_data *msr_info)
> /* ...but clean it before doing the actual write */
> vcpu->arch.time_offset = data & ~(PAGE_MASK | 1);
> + /* Check that the address is 32-byte aligned. */
> + if (vcpu->arch.time_offset &
> + (sizeof(struct pvclock_vcpu_time_info) - 1))
> + break;
> +
> vcpu->arch.time_page =
> gfn_to_page(vcpu->kvm, data >> PAGE_SHIFT);
> --
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