Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
MIME-Version: 1.0
References: <20220516154310.3685678-1-Ashish.Kalra@amd.com>
In-Reply-To: <20220516154310.3685678-1-Ashish.Kalra@amd.com>
From:   Peter Gonda <pgonda@google.com>
Date:   Thu, 19 May 2022 10:08:44 -0700
Message-ID: <CAMkAt6r8yaiL38AqZWpbe=UT_MAV8fuOSvPCLJBAsT9pisf2tg@mail.gmail.com>
Subject: Re: [PATCH v2] KVM: SVM: Use kzalloc for sev ioctl interfaces to
 prevent kernel memory leak.
To:     Ashish Kalra <Ashish.Kalra@amd.com>
Cc:     Paolo Bonzini <pbonzini@redhat.com>,
        Sean Christopherson <seanjc@google.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>,
        "H. Peter Anvin" <hpa@zytor.com>, Joerg Roedel <joro@8bytes.org>,
        "Lendacky, Thomas" <Thomas.Lendacky@amd.com>,
        Borislav Petkov <bp@alien8.de>,
        "the arch/x86 maintainers" <x86@kernel.org>,
        kvm list <kvm@vger.kernel.org>,
        LKML <linux-kernel@vger.kernel.org>,
        Andy Nguyen <theflow@google.com>,
        David Rientjes <rientjes@google.com>,
        John Allen <john.allen@amd.com>, stable@vger.kernel.org,
        Michael Roth <michael.roth@amd.com>
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

On Mon, May 16, 2022 at 8:43 AM Ashish Kalra <Ashish.Kalra@amd.com> wrote:
>
> From: Ashish Kalra <ashish.kalra@amd.com>
>
> For some sev ioctl interfaces, the length parameter that is passed maybe
> less than or equal to SEV_FW_BLOB_MAX_SIZE, but larger than the data
> that PSP firmware returns. In this case, kmalloc will allocate memory
> that is the size of the input rather than the size of the data.
> Since PSP firmware doesn't fully overwrite the allocated buffer, these
> sev ioctl interface may return uninitialized kernel slab memory.
>
> Reported-by: Andy Nguyen <theflow@google.com>
> Suggested-by: David Rientjes <rientjes@google.com>
> Suggested-by: Peter Gonda <pgonda@google.com>
> Cc: kvm@vger.kernel.org
> Cc: stable@vger.kernel.org
> Cc: linux-kernel@vger.kernel.org
> Fixes: eaf78265a4ab3 ("KVM: SVM: Move SEV code to separate file")
> Fixes: 2c07ded06427d ("KVM: SVM: add support for SEV attestation command")
> Fixes: 4cfdd47d6d95a ("KVM: SVM: Add KVM_SEV SEND_START command")
> Fixes: d3d1af85e2c75 ("KVM: SVM: Add KVM_SEND_UPDATE_DATA command")
> Fixes: eba04b20e4861 ("KVM: x86: Account a variety of miscellaneous allocations")
> Signed-off-by: Ashish Kalra <ashish.kalra@amd.com>

Reviewed-by: Peter Gonda <pgonda@google.com>