linux-kernel - Re: [PATCH RFC 03/39] KVM: x86/xen: register shared

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Tue, 01 Dec 2020 13:07:23 +0000
From:   David Woodhouse <dwmw2@...radead.org>
To:     Joao Martins <joao.m.martins@...cle.com>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Cc:     Ankur Arora <ankur.a.arora@...cle.com>,
        Boris Ostrovsky <boris.ostrovsky@...cle.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Radim Krčmář <rkrcmar@...hat.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        "H. Peter Anvin" <hpa@...or.com>, x86@...nel.org
Subject: Re: [PATCH RFC 03/39] KVM: x86/xen: register shared_info page

On Wed, 2019-02-20 at 20:15 +0000, Joao Martins wrote:
> +static int kvm_xen_shared_info_init(struct kvm *kvm, gfn_t gfn)
> +{
> +       struct shared_info *shared_info;
> +       struct page *page;
> +
> +       page = gfn_to_page(kvm, gfn);
> +       if (is_error_page(page))
> +               return -EINVAL;
> +
> +       kvm->arch.xen.shinfo_addr = gfn;
> +
> +       shared_info = page_to_virt(page);
> +       memset(shared_info, 0, sizeof(struct shared_info));
> +       kvm->arch.xen.shinfo = shared_info;
> +       return 0;
> +}
> +

Hm.

How come we get to pin the page and directly dereference it every time,
while kvm_setup_pvclock_page() has to use kvm_write_guest_cached()
instead?

If that was allowed, wouldn't it have been a much simpler fix for
CVE-2019-3016? What am I missing?

Should I rework these to use kvm_write_guest_cached()? 



Download attachment "smime.p7s" of type "application/x-pkcs7-signature" (5174 bytes)