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Date:   Mon, 29 Apr 2019 18:36:02 +0200
From:   Borislav Petkov <bp@alien8.de>
To:     "Singh, Brijesh" <brijesh.singh@amd.com>
Cc:     "kvm@vger.kernel.org" <kvm@vger.kernel.org>,
        "qemu-devel@nongnu.org" <qemu-devel@nongnu.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>,
        "H. Peter Anvin" <hpa@zytor.com>,
        Paolo Bonzini <pbonzini@redhat.com>,
        Radim =?utf-8?B?S3LEjW3DocWZ?= <rkrcmar@redhat.com>,
        Joerg Roedel <joro@8bytes.org>,
        "Lendacky, Thomas" <Thomas.Lendacky@amd.com>,
        "x86@kernel.org" <x86@kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [RFC PATCH v1 01/10] KVM: SVM: Add KVM_SEV SEND_START command
Message-ID: <20190429163602.GE2324@zn.tnic>
References: <20190424160942.13567-1-brijesh.singh@amd.com>
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 <20190426141042.GF4608@zn.tnic>
 <e6f8da38-b8dd-a9c5-a358-5f33b6ea7b37@amd.com>
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On Mon, Apr 29, 2019 at 03:01:24PM +0000, Singh, Brijesh wrote:
> Practically I don't see any reason why caller would do that but
> theoretically it can. If we cache the len then we also need to consider
> adding another flag to hint whether userspace ever requested length.
> e.g an application can compute the length of session blob by looking at
> the API version and spec and may never query the length.
> 
> > I mean I'm still thinking defensively here but maybe the only thing that
> > would happen here with a bigger buffer is if the kmalloc() would fail,
> > leading to eventual failure of the migration.
> > 
> > If the code limits the allocation to some sane max length, the migration
> > won't fail even if userspace gives it too big values...

So what about this? Limiting to a sane length...

-- 
Regards/Gruss,
    Boris.

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