----- Original Message ----- > From: "David Hildenbrand" <[email protected]> > To: "Paolo Bonzini" <[email protected]>, [email protected], > [email protected] > Cc: [email protected] > 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 <[email protected]> > > Signed-off-by: Paolo Bonzini <[email protected]> > > --- > > 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 >
