From: David Hildenbrand <david@redhat.com>
To: Paolo Bonzini <pbonzini@redhat.com>,
linux-kernel@vger.kernel.org, kvm@vger.kernel.org
Cc: dvyukov@google.com
Subject: Re: [PATCH] kvm: fix page struct leak in handle_vmon
Date: Wed, 25 Jan 2017 10:31:13 +0100 [thread overview]
Message-ID: <0cdfcfea-f1f6-fbcb-887a-dae659e2b844@redhat.com> (raw)
In-Reply-To: <1485255381-18069-1-git-send-email-pbonzini@redhat.com>
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@google.com>
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> ---
> 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
next prev parent reply other threads:[~2017-01-25 9:31 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-01-24 10:56 [PATCH] kvm: fix page struct leak in handle_vmon Paolo Bonzini
2017-01-25 9:31 ` David Hildenbrand [this message]
2017-01-25 9:52 ` Paolo Bonzini
2017-01-25 9:57 ` David Hildenbrand
2017-01-25 10:11 ` David Hildenbrand
2017-01-25 10:35 ` Paolo Bonzini
2017-01-25 10:11 ` David Hildenbrand
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