Re: [PATCH 1/3] KVM: x86: Avoid overflowing nr_mmu_pages in kvm_arch_commit_memory_region()
From: Sean Christopherson
Date: Mon Nov 29 2021 - 17:44:15 EST
On Fri, Nov 26, 2021, Maciej S. Szmigiero wrote:
> From: "Maciej S. Szmigiero" <maciej.szmigiero@xxxxxxxxxx>
>
> With kvm->nr_memslot_pages capped at ULONG_MAX we can't safely multiply it
> by KVM_PERMILLE_MMU_PAGES (20) since this operation can possibly overflow
> an unsigned long variable.
>
> Rewrite this "* 20 / 1000" operation as "/ 50" instead to avoid such
> overflow.
>
> Signed-off-by: Maciej S. Szmigiero <maciej.szmigiero@xxxxxxxxxx>
> ---
Reviewed-by: Sean Christopherson <seanjc@xxxxxxxxxx>