Re: [PATCH v2 2/2] KVM: TDX: Fix a benign off-by-one bug on the end GPA for INIT_MEM_REGION
Binbin Wu <[email protected]>
| Newsgroups | org.kernel.vger.kvm,org.kernel.vger.linux-kernel |
|---|---|
| Message-ID | <[email protected]> |
On 8/7/2026 1:06 AM, Sean Christopherson wrote:
> When verifying that the incoming GPA rage for INIT_MEM_REGION doesn't wrap,
> check the inclusive last GPA, not the exclusive last GPA. Super duper
> technically, it's ok if the very last GPA is -1ull. In practice, the flaw
> is benign as KVM x86 disallows memslots with GPAs that exceed MAXPHYADDR,
> i.e. INIT_MEM_REGION would fail with -EINVAL anyways due to the memslot
> check in kvm_gmem_populate().
>
> Opportunistically use check_add_overflow() instead of manually checking for
> wrap, mostly so that the inclusive math doesn't need to be copy+pasted in
> the "is private" check.
>
> Fixes: c846b451d3c5 ("KVM: TDX: Add an ioctl to create initial guest memory")
> Signed-off-by: Sean Christopherson <[email protected]>
Reviewed-by: Binbin Wu <[email protected]>