----- Original Message -----
> From: "David Hildenbrand" <david@xxxxxxxxxx>
> To: "Paolo Bonzini" <pbonzini@xxxxxxxxxx>, linux-kernel@xxxxxxxxxxxxxxx, kvm@xxxxxxxxxxxxxxx
> Cc: dvyukov@xxxxxxxxxx
> Sent: Wednesday, January 25, 2017 10:31:13 AM
> Subject: Re: [PATCH] kvm: fix page struct leak in handle_vmon
>
> 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?
I don't think kmap can fail (page_address can)?
Paolo
> > 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
>
