* [PATCH] kvm: fix page struct leak in handle_vmon
@ 2017-01-24 10:56 Paolo Bonzini
2017-01-25 9:31 ` David Hildenbrand
2017-01-25 10:11 ` David Hildenbrand
0 siblings, 2 replies; 7+ messages in thread
From: Paolo Bonzini @ 2017-01-24 10:56 UTC (permalink / raw)
To: linux-kernel, kvm; +Cc: dvyukov
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) {
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:
--
1.8.3.1
^ permalink raw reply related [flat|nested] 7+ messages in thread
* Re: [PATCH] kvm: fix page struct leak in handle_vmon
2017-01-24 10:56 [PATCH] kvm: fix page struct leak in handle_vmon Paolo Bonzini
@ 2017-01-25 9:31 ` David Hildenbrand
2017-01-25 9:52 ` Paolo Bonzini
2017-01-25 10:11 ` David Hildenbrand
1 sibling, 1 reply; 7+ messages in thread
From: David Hildenbrand @ 2017-01-25 9:31 UTC (permalink / raw)
To: Paolo Bonzini, linux-kernel, kvm; +Cc: dvyukov
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
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH] kvm: fix page struct leak in handle_vmon
2017-01-25 9:31 ` David Hildenbrand
@ 2017-01-25 9:52 ` Paolo Bonzini
2017-01-25 9:57 ` David Hildenbrand
0 siblings, 1 reply; 7+ messages in thread
From: Paolo Bonzini @ 2017-01-25 9:52 UTC (permalink / raw)
To: David Hildenbrand; +Cc: linux-kernel, kvm, dvyukov
----- Original Message -----
> 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
> 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@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?
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
>
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH] kvm: fix page struct leak in handle_vmon
2017-01-25 9:52 ` Paolo Bonzini
@ 2017-01-25 9:57 ` David Hildenbrand
2017-01-25 10:11 ` David Hildenbrand
0 siblings, 1 reply; 7+ messages in thread
From: David Hildenbrand @ 2017-01-25 9:57 UTC (permalink / raw)
To: Paolo Bonzini; +Cc: linux-kernel, kvm, dvyukov
Am 25.01.2017 um 10:52 schrieb Paolo Bonzini:
>
>
> ----- Original Message -----
>> 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
>> 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@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?
>
> I don't think kmap can fail (page_address can)?
Then I wonder why there are some checks:
e.g. nested_vmx_merge_msr_bitmap()
msr_bitmap_l1 = (unsigned long *)kmap(page);
if (!msr_bitmap_l1) {
// no unmap
...
return false;
or vmx_complete_nested_posted_interrupt()
vapic_page = kmap(vmx->nested.virtual_apic_page);
if (!vapic_page) {
// no unmap
...
return -ENOMEM;
But there is also no check in handle_vmptrld() for example.
>
> Paolo
--
David
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH] kvm: fix page struct leak in handle_vmon
2017-01-25 9:57 ` David Hildenbrand
@ 2017-01-25 10:11 ` David Hildenbrand
2017-01-25 10:35 ` Paolo Bonzini
0 siblings, 1 reply; 7+ messages in thread
From: David Hildenbrand @ 2017-01-25 10:11 UTC (permalink / raw)
To: Paolo Bonzini; +Cc: linux-kernel, kvm, dvyukov
Am 25.01.2017 um 10:57 schrieb David Hildenbrand:
> Am 25.01.2017 um 10:52 schrieb Paolo Bonzini:
>>
>>
>> ----- Original Message -----
>>> 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
>>> 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@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?
>>
>> I don't think kmap can fail (page_address can)?
>
> Then I wonder why there are some checks:
>
> e.g. nested_vmx_merge_msr_bitmap()
>
> msr_bitmap_l1 = (unsigned long *)kmap(page);
> if (!msr_bitmap_l1) {
> // no unmap
> ...
> return false;
>
> or vmx_complete_nested_posted_interrupt()
>
> vapic_page = kmap(vmx->nested.virtual_apic_page);
> if (!vapic_page) {
> // no unmap
> ...
> return -ENOMEM;
>
>
> But there is also no check in handle_vmptrld() for example.
>
>
>>
>> Paolo
>
>
Think you're right it can't fail.
So something like that could most likely be done
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index a236dec..a9be221 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -4973,10 +4973,6 @@ static int
vmx_complete_nested_posted_interrupt(struct kvm_vcpu *vcpu)
return 0;
vapic_page = kmap(vmx->nested.virtual_apic_page);
- if (!vapic_page) {
- WARN_ON(1);
- return -ENOMEM;
- }
__kvm_apic_update_irr(vmx->nested.pi_desc->pir, vapic_page);
kunmap(vmx->nested.virtual_apic_page);
@@ -9730,12 +9726,6 @@ static inline bool
nested_vmx_merge_msr_bitmap(struct kvm_vcpu *vcpu,
return false;
}
msr_bitmap_l1 = (unsigned long *)kmap(page);
- if (!msr_bitmap_l1) {
- nested_release_page_clean(page);
- WARN_ON(1);
- return false;
- }
-
memset(msr_bitmap_l0, 0xff, PAGE_SIZE);
if (nested_cpu_has_virt_x2apic_mode(vmcs12)) {
--
David
^ permalink raw reply related [flat|nested] 7+ messages in thread
* Re: [PATCH] kvm: fix page struct leak in handle_vmon
2017-01-24 10:56 [PATCH] kvm: fix page struct leak in handle_vmon Paolo Bonzini
2017-01-25 9:31 ` David Hildenbrand
@ 2017-01-25 10:11 ` David Hildenbrand
1 sibling, 0 replies; 7+ messages in thread
From: David Hildenbrand @ 2017-01-25 10:11 UTC (permalink / raw)
To: Paolo Bonzini, linux-kernel, kvm; +Cc: dvyukov
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) {
> 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:
>
Reviewed-by: David Hildenbrand <david@redhat.com>
--
David
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH] kvm: fix page struct leak in handle_vmon
2017-01-25 10:11 ` David Hildenbrand
@ 2017-01-25 10:35 ` Paolo Bonzini
0 siblings, 0 replies; 7+ messages in thread
From: Paolo Bonzini @ 2017-01-25 10:35 UTC (permalink / raw)
To: David Hildenbrand; +Cc: linux-kernel, kvm, dvyukov
On 25/01/2017 11:11, David Hildenbrand wrote:
> Am 25.01.2017 um 10:57 schrieb David Hildenbrand:
>> Am 25.01.2017 um 10:52 schrieb Paolo Bonzini:
>>>
>>>
>>> ----- Original Message -----
>>>> 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
>>>> 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@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?
>>>
>>> I don't think kmap can fail (page_address can)?
>>
>> Then I wonder why there are some checks:
>>
>> e.g. nested_vmx_merge_msr_bitmap()
>>
>> msr_bitmap_l1 = (unsigned long *)kmap(page);
>> if (!msr_bitmap_l1) {
>> // no unmap
>> ...
>> return false;
>>
>> or vmx_complete_nested_posted_interrupt()
>>
>> vapic_page = kmap(vmx->nested.virtual_apic_page);
>> if (!vapic_page) {
>> // no unmap
>> ...
>> return -ENOMEM;
>>
>>
>> But there is also no check in handle_vmptrld() for example.
>>
>>
>>>
>>> Paolo
>>
>>
>
> Think you're right it can't fail.
>
> So something like that could most likely be done
>
> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
> index a236dec..a9be221 100644
> --- a/arch/x86/kvm/vmx.c
> +++ b/arch/x86/kvm/vmx.c
> @@ -4973,10 +4973,6 @@ static int
> vmx_complete_nested_posted_interrupt(struct kvm_vcpu *vcpu)
> return 0;
>
> vapic_page = kmap(vmx->nested.virtual_apic_page);
> - if (!vapic_page) {
> - WARN_ON(1);
> - return -ENOMEM;
> - }
> __kvm_apic_update_irr(vmx->nested.pi_desc->pir, vapic_page);
> kunmap(vmx->nested.virtual_apic_page);
>
> @@ -9730,12 +9726,6 @@ static inline bool
> nested_vmx_merge_msr_bitmap(struct kvm_vcpu *vcpu,
> return false;
> }
> msr_bitmap_l1 = (unsigned long *)kmap(page);
> - if (!msr_bitmap_l1) {
> - nested_release_page_clean(page);
> - WARN_ON(1);
> - return false;
> - }
> -
> memset(msr_bitmap_l0, 0xff, PAGE_SIZE);
>
> if (nested_cpu_has_virt_x2apic_mode(vmcs12)) {
Yes, definitely. Want to send a patch?
Paolo
^ permalink raw reply [flat|nested] 7+ messages in thread
end of thread, other threads:[~2017-01-25 10:35 UTC | newest]
Thread overview: 7+ messages (download: mbox.gz / follow: Atom feed)
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2017-01-24 10:56 [PATCH] kvm: fix page struct leak in handle_vmon Paolo Bonzini
2017-01-25 9:31 ` David Hildenbrand
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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