linux-kernel - Re: [PATCH gmem] KVM: Fix off-by-one error when querying attributes in xarray

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Date:   Tue, 24 Oct 2023 10:52:03 +0800
From:   Binbin Wu <binbin.wu@...ux.intel.com>
To:     Sean Christopherson <seanjc@...gle.com>
Cc:     Paolo Bonzini <pbonzini@...hat.com>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH gmem] KVM: Fix off-by-one error when querying attributes
 in xarray



On 10/24/2023 4:35 AM, Sean Christopherson wrote:
> Subtract -1 from kvm_range_has_memory_attributes()'s @end when using
> xas_find(), as "end" is exclusive whereas xas_find() takes an inclusive
> "max" as the maximal index to find/return.
>
> Reported-by: Binbin Wu <binbin.wu@...ux.intel.com>
> Signed-off-by: Sean Christopherson <seanjc@...gle.com>

Reviewed-by: Binbin Wu<binbin.wu@...ux.intel.com>



> ---
>   virt/kvm/kvm_main.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> index 959e866c84f0..12458959dd25 100644
> --- a/virt/kvm/kvm_main.c
> +++ b/virt/kvm/kvm_main.c
> @@ -2447,7 +2447,7 @@ bool kvm_range_has_memory_attributes(struct kvm *kvm, gfn_t start, gfn_t end,
>   	rcu_read_lock();
>   
>   	if (!attrs) {
> -		has_attrs = !xas_find(&xas, end);
> +		has_attrs = !xas_find(&xas, end - 1);
>   		goto out;
>   	}
>   
>
> base-commit: 911b515af3ec5f53992b9cc162cf7d3893c2fbe2