From mboxrd@z Thu Jan 1 00:00:00 1970 From: Paolo Bonzini Subject: Re: [PATCH] kvm: fix page struct leak in handle_vmon Date: Wed, 25 Jan 2017 04:52:06 -0500 (EST) Message-ID: <692606753.12365942.1485337926527.JavaMail.zimbra@redhat.com> References: <1485255381-18069-1-git-send-email-pbonzini@redhat.com> <0cdfcfea-f1f6-fbcb-887a-dae659e2b844@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org, dvyukov@google.com To: David Hildenbrand Return-path: In-Reply-To: <0cdfcfea-f1f6-fbcb-887a-dae659e2b844@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: kvm.vger.kernel.org ----- Original Message ----- > From: "David Hildenbrand" > To: "Paolo Bonzini" , linux-kernel@vger.kernel.org, kvm@vger.kernel.org > Cc: dvyukov@google.com > 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 > > Signed-off-by: Paolo Bonzini > > --- > > 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 >