On Mon, May 11, 2020 at 3:56 PM Jim Mattson <jmattson@xxxxxxxxxx> wrote:
>
> Bank_num is a one-based count of banks, not a zero-based index. It
> overflows the allocated space only when strictly greater than
> KVM_MAX_MCE_BANKS.
>
> Fixes: a9e38c3e01ad ("KVM: x86: Catch potential overrun in MCE setup")
> Signed-off-by: Jue Wang <juew@xxxxxxxxxx>
> Signed-off-by: Jim Mattson <jmattson@xxxxxxxxxx>
> Reviewed-by: Peter Shier <pshier@xxxxxxxxxx>
> ---
> arch/x86/kvm/x86.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index d786c7d27ce5..5bf45c9aa8e5 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -3751,7 +3751,7 @@ static int kvm_vcpu_ioctl_x86_setup_mce(struct kvm_vcpu *vcpu,
> unsigned bank_num = mcg_cap & 0xff, bank;
>
> r = -EINVAL;
> - if (!bank_num || bank_num >= KVM_MAX_MCE_BANKS)
> + if (!bank_num || bank_num > KVM_MAX_MCE_BANKS)
> goto out;
> if (mcg_cap & ~(kvm_mce_cap_supported | 0xff | 0xff0000))
> goto out;
> --
> 2.26.2.645.ge9eca65c58-goog
>
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