linux-kernel - Re: [PATCH v3 02/11] KVM: SVM: Add KVM_SEND_UPDATE

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Date:   Tue, 12 Nov 2019 14:23:06 -0800
From:   Peter Gonda <pgonda@...gle.com>
To:     "Singh, Brijesh" <brijesh.singh@....com>
Cc:     "kvm@...r.kernel.org" <kvm@...r.kernel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        "H. Peter Anvin" <hpa@...or.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Radim Krčmář <rkrcmar@...hat.com>,
        Joerg Roedel <joro@...tes.org>, Borislav Petkov <bp@...e.de>,
        "Lendacky, Thomas" <Thomas.Lendacky@....com>,
        "x86@...nel.org" <x86@...nel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3 02/11] KVM: SVM: Add KVM_SEND_UPDATE_DATA command

On Wed, Jul 10, 2019 at 1:14 PM Singh, Brijesh <brijesh.singh@....com> wrote:

> +static int sev_send_update_data(struct kvm *kvm, struct kvm_sev_cmd *argp)
> +{
> +       struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info;
> +       struct sev_data_send_update_data *data;
> +       struct kvm_sev_send_update_data params;
> +       void *hdr = NULL, *trans_data = NULL;
> +       struct page **guest_page = NULL;
> +       unsigned long n;
> +       int ret, offset;
> +
> +       if (!sev_guest(kvm))
> +               return -ENOTTY;
> +
> +       if (copy_from_user(&params, (void __user *)(uintptr_t)argp->data,
> +                       sizeof(struct kvm_sev_send_update_data)))
> +               return -EFAULT;
> +
> +       data = kzalloc(sizeof(*data), GFP_KERNEL);
> +       if (!data)
> +               return -ENOMEM;
> +
> +       /* userspace wants to query either header or trans length */
> +       if (!params.trans_len || !params.hdr_len)
> +               goto cmd;
> +
> +       ret = -EINVAL;
> +       if (!params.trans_uaddr || !params.guest_uaddr ||
> +           !params.guest_len || !params.hdr_uaddr)
> +               goto e_free;
> +
> +       /* Check if we are crossing the page boundry */
> +       ret = -EINVAL;
> +       offset = params.guest_uaddr & (PAGE_SIZE - 1);
> +       if ((params.guest_len + offset > PAGE_SIZE))
> +               goto e_free;
> +
> +       ret = -ENOMEM;
> +       hdr = kmalloc(params.hdr_len, GFP_KERNEL);
> +       if (!hdr)
> +               goto e_free;

Should we be checking params.hdr_len against SEV_FW_BLOB_MAX_SIZE?

> +
> +       data->hdr_address = __psp_pa(hdr);
> +       data->hdr_len = params.hdr_len;
> +
> +       ret = -ENOMEM;
> +       trans_data = kmalloc(params.trans_len, GFP_KERNEL);
> +       if (!trans_data)
> +               goto e_free;

Ditto, should we be checking params.hdr_len against SEV_FW_BLOB_MAX_SIZE?