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([2001:b07:6468:f312:60bb:f5bd:83ff:ec47]) by smtp.gmail.com with ESMTPSA id h20sm4479572wma.6.2020.05.15.10.49.21 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 15 May 2020 10:49:21 -0700 (PDT) Subject: Re: [PATCH] KVM: x86: Fix off-by-one error in kvm_vcpu_ioctl_x86_setup_mce To: Jim Mattson , kvm@vger.kernel.org Cc: Jue Wang , Peter Shier References: <20200511225616.19557-1-jmattson@google.com> From: Paolo Bonzini Message-ID: Date: Fri, 15 May 2020 19:49:20 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.6.0 MIME-Version: 1.0 In-Reply-To: <20200511225616.19557-1-jmattson@google.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On 12/05/20 00:56, Jim Mattson 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 > Signed-off-by: Jim Mattson > Reviewed-by: Peter Shier > --- > 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; > Queued, thanks. Paolo