Am 24.01.2017 um 11:56 schrieb Paolo Bonzini:
> handle_vmon gets a reference on VMXON region page,
> but does not release it. Release the reference.
>
> Found by syzkaller; based on a patch by Dmitry.
>
> Reported-by: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
> Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
> ---
> arch/x86/kvm/vmx.c | 9 +++++++--
> 1 file changed, 7 insertions(+), 2 deletions(-)
>
> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
> index 42cc3d6f4d20..0f7345035210 100644
> --- a/arch/x86/kvm/vmx.c
> +++ b/arch/x86/kvm/vmx.c
> @@ -7085,13 +7085,18 @@ static int nested_vmx_check_vmptr(struct kvm_vcpu *vcpu, int exit_reason,
> }
>
> page = nested_get_page(vcpu, vmptr);
> - if (page == NULL ||
> - *(u32 *)kmap(page) != VMCS12_REVISION) {
> + if (page == NULL) {
> nested_vmx_failInvalid(vcpu);
> + return kvm_skip_emulated_instruction(vcpu);
> + }
> + if (*(u32 *)kmap(page) != VMCS12_REVISION) {
shouldn't we also check if kmap even returned a valid pointer before
dereferencing it?
David thinks so.
> kunmap(page);
> + nested_release_page_clean(page);
> + nested_vmx_failInvalid(vcpu);
> return kvm_skip_emulated_instruction(vcpu);
> }
> kunmap(page);
> + nested_release_page_clean(page);
> vmx->nested.vmxon_ptr = vmptr;
> break;
> case EXIT_REASON_VMCLEAR:
>
--
David
