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AJvYcCXMlxh4c/RmuLl6a5aj4fWntsmNXrY+LJEmjWbed0hLs0B69wSgQTuD5/rOvxJhpQq64vGgVQ3m7Y2rf1M=@vger.kernel.org X-Gm-Message-State: AOJu0YxbG9Av71XKmBWePNZ39UUMYbuY0DPlU3Z81wwIGl5n5bcDRiPu 2cJIqvpHrHutgFDx0YcMIPHB1jbqIDTE4cRJDP6EKR3UbCk89nUFbrmT2QW7PE0+G91ux+luqmx z7QQf3w== X-Google-Smtp-Source: AGHT+IHFuX9HZZ+3Ap9KfIP9YqmTsis1lj1RdPwzOjpZRGAUvoQwOVBBtSltO2l5sj1D1kqm/ucDlsqS4As= X-Received: from pfet12.prod.google.com ([2002:aa7:938c:0:b0:772:32b1:58f9]) (user=seanjc job=prod-delivery.src-stubby-dispatcher) by 2002:a05:6a00:1394:b0:771:ef79:9338 with SMTP id d2e1a72fcca58-7742def5d1emr11472262b3a.21.1757375663426; Mon, 08 Sep 2025 16:54:23 -0700 (PDT) Date: Mon, 8 Sep 2025 16:54:21 -0700 In-Reply-To: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20250826233734.4011090-1-seanjc@google.com> Message-ID: Subject: Re: [PATCH] KVM: SEV: Reject non-positive effective lengths during LAUNCH_UPDATE From: Sean Christopherson To: Tom Lendacky Cc: Paolo Bonzini , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Michael Roth Content-Type: text/plain; charset="us-ascii" On Mon, Sep 08, 2025, Tom Lendacky wrote: > On 8/26/25 18:37, Sean Christopherson wrote: > > diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c > > index f4381878a9e5..746a57bf1f71 100644 > > --- a/arch/x86/kvm/svm/sev.c > > +++ b/arch/x86/kvm/svm/sev.c > > @@ -2360,6 +2360,8 @@ static int snp_launch_update(struct kvm *kvm, struct kvm_sev_cmd *argp) > > return -EINVAL; > > > > npages = params.len / PAGE_SIZE; > > + if (npages <= 0) > > + return -EINVAL; > > Would it make sense to include a !params.len in the giant if check just > above this, e.g.: > > if (!params.len || !PAGE_ALIGNED(params.len) || ... > > ? > > That way everything related to checking "params" remains in the one > statement. Oh, yeah, duh. I overlooked that the only way for npages to be '0' is if params.len is '0', because the PAGE_ALIGNED() check will handed len == 1-4095. Will send a v2. Thanks Tom!