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[91.219.240.2]) by smtp.gmail.com with ESMTPSA id 37sm3604512wrk.61.2020.05.15.05.36.48 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 15 May 2020 05:36:48 -0700 (PDT) From: Vitaly Kuznetsov To: Jim Mattson , kvm@vger.kernel.org Cc: Jue Wang , Peter Shier , Paolo Bonzini Subject: Re: [PATCH] KVM: x86: Fix off-by-one error in kvm_vcpu_ioctl_x86_setup_mce In-Reply-To: <20200511225616.19557-1-jmattson@google.com> References: <20200511225616.19557-1-jmattson@google.com> Date: Fri, 15 May 2020 14:36:47 +0200 Message-ID: <87r1vlv0gw.fsf@vitty.brq.redhat.com> MIME-Version: 1.0 Content-Type: text/plain Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org Jim Mattson writes: > 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; /* it would be great to get rid of bare unsigned-s in kvm_vcpu_ioctl_x86_setup_mce/kvm_vcpu_ioctl_x86_set_mce ... */ > > 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; Reviewed-by: Vitaly Kuznetsov -- Vitaly