linux-kernel - Re: [PATCH V3 01/10] virtio-blk: validate num

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Message-ID: <20211020084405.yrnbouwljqkoopsk@steredhat>
Date:   Wed, 20 Oct 2021 10:44:05 +0200
From:   Stefano Garzarella <sgarzare@...hat.com>
To:     "Michael S. Tsirkin" <mst@...hat.com>
Cc:     Jason Wang <jasowang@...hat.com>,
        virtualization@...ts.linux-foundation.org,
        linux-kernel@...r.kernel.org, f.hetzelt@...berlin.de,
        david.kaplan@....com, konrad.wilk@...cle.com,
        Paolo Bonzini <pbonzini@...hat.com>,
        Stefan Hajnoczi <stefanha@...hat.com>
Subject: Re: [PATCH V3 01/10] virtio-blk: validate num_queues during probe

On Wed, Oct 20, 2021 at 03:37:31AM -0400, Michael S. Tsirkin wrote:
>On Wed, Oct 20, 2021 at 09:18:17AM +0200, Stefano Garzarella wrote:
>> On Tue, Oct 19, 2021 at 03:01:43PM +0800, Jason Wang wrote:
>> > If an untrusted device neogitates BLK_F_MQ but advertises a zero
>>
>> s/neogitates/negotiates
>>
>> > num_queues, the driver may end up trying to allocating zero size
>> > buffers where ZERO_SIZE_PTR is returned which may pass the checking
>> > against the NULL. This will lead unexpected results.
>> >
>> > Fixing this by failing the probe in this case.
>> >
>> > Cc: Paolo Bonzini <pbonzini@...hat.com>
>> > Cc: Stefan Hajnoczi <stefanha@...hat.com>
>> > Cc: Stefano Garzarella <sgarzare@...hat.com>
>> > Signed-off-by: Jason Wang <jasowang@...hat.com>
>> > ---
>> > drivers/block/virtio_blk.c | 4 ++++
>> > 1 file changed, 4 insertions(+)
>>
>> Should we CC stable?
>>
>> Reviewed-by: Stefano Garzarella <sgarzare@...hat.com>
>
>No IMO - I don't think we can reasonably expect stable to become
>protected against attacks on encrypted guests. That's
>a new feature, not a bugfix.

Yep, make sense.
I had only seen the single patch, not the entire series, and it seemed 
like a fix.

Viewed as a whole, it makes sense to consider it a new feature to 
improve audits in the guest.

Thanks,
Stefano