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SubjectRe: [PATCH] KVM: validate userspace input in kvm_clear_dirty_log_protect()
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On 11/01/19 14:49, Radim Krčmář wrote:
> 2019-01-08 17:28+0100, Tomas Bortoli:
>> Hi Paolo,
>>
>> On 1/7/19 11:42 PM, Paolo Bonzini wrote:
>>> On 02/01/19 18:29, Tomas Bortoli wrote:
>>>> n = kvm_dirty_bitmap_bytes(memslot);
>>>> +
>>>> + if (n << 3 < log->num_pages || log->first_page > log->num_pages)
>>>> + return -EINVAL;
>>>> +
>>>
>>> This should be
>>>
>>> if (log->first_page > memslot->npages ||
>
> (Wouldn't this be clearer with a >= instead?)

log->first_page == memslot->npages is technically okay if log->num_pages
is zero.

Paolo

>>> log->num_pages > memslot->npages - log->first_page)
>>> return -EINVAL;
>>>
>>> i.e. the comparison should check the last page in the range, not the
>>> number of pages. In addition, using "n" is unnecessary since we do have
>>> the memslot. I'll do the changes myself if you prefer, but an ack would
>>> be nice.
>>>
>>>
>>
>>
>> Yeah, I agree. Thanks for the reply and sure you can do the changes, np :)
>
> Done that and applied, thanks.
>

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