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References: <6f79d9be-fa76-3a06-2612-f44f3a18ece7@redhat.com> <20190114234728.49239-1-tmroeder@google.com>
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From:   Jim Mattson <jmattson@google.com>
Date:   Mon, 14 Jan 2019 16:03:35 -0800
Message-ID: <CALMp9eSovFPZOmztDtzcf0BnkoV1=4ua1ymOfuEg0K7acug24A@mail.gmail.com>
Subject: Re: [RFC PATCH] kvm: x86/vmx: Use kzalloc for cached_vmcs12
To:     Tom Roeder <tmroeder@google.com>
Cc:     Paolo Bonzini <pbonzini@redhat.com>,
        =?UTF-8?B?UmFkaW0gS3LEjW3DocWZ?= <rkrcmar@redhat.com>,
        Liran Alon <liran.alon@oracle.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
        "H . Peter Anvin" <hpa@zytor.com>,
        "the arch/x86 maintainers" <x86@kernel.org>,
        kvm list <kvm@vger.kernel.org>,
        LKML <linux-kernel@vger.kernel.org>,
        syzbot+ded1696f6b50b615b630@syzkaller.appspotmail.com
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On Mon, Jan 14, 2019 at 3:48 PM Tom Roeder <tmroeder@google.com> wrote:
>
> This changes the allocation of cached_vmcs12 to use kzalloc instead of
> kmalloc. This removes the information leak found by Syzkaller (see
> Reported-by) in this case and prevents similar leaks from happening
> based on cached_vmcs12.
>
> The email from Syszkaller led to a discussion about a patch in early
> November on the KVM list (I've made this a reply to that thread), but
> the current upstream kernel still has kmalloc instead of kzalloc for
> cached_vmcs12 and cached_shadow_vmcs12. This RFC proposes changing to
> kzalloc for defense in depth.
>
> Tested: rebuilt but not tested, since this is an RFC
>
> Reported-by: syzbot+ded1696f6b50b615b630@syzkaller.appspotmail.com
> Signed-off-by: Tom Roeder <tmroeder@google.com>
Reviewed-by: Jim Mattson <jmattson@google.com>