Re: [PATCH v5] virtio-blk: Add validation for block size in config space

[Max Gurtovoy]

On 8/23/2021 11:35 AM, Yongji Xie wrote:
> On Mon, Aug 23, 2021 at 4:07 PM Max Gurtovoy <mgurtovoy@xxxxxxxxxx> wrote:
> > On 8/23/2021 7:31 AM, Yongji Xie wrote:
> > > On Mon, Aug 23, 2021 at 7:17 AM Max Gurtovoy <mgurtovoy@xxxxxxxxxx> wrote:
> > > > On 8/9/2021 1:16 PM, Xie Yongji wrote:
> > > > > An untrusted device might presents an invalid block size
> > > > > in configuration space. This tries to add validation for it
> > > > > in the validate callback and clear the VIRTIO_BLK_F_BLK_SIZE
> > > > > feature bit if the value is out of the supported range.
> > > > This is not clear to me. What is untrusted device ? is it a buggy device ?
> > > A buggy device, the devices in an encrypted VM, or a userspace device
> > > created by VDUSE [1].
> > >
> > > [1] https://lore.kernel.org/kvm/20210818120642.165-1-xieyongji@xxxxxxxxxxxxx/
> > if it's a userspace device, why don't you fix its control path code
> > instead of adding workarounds in the kernel driver ?
> VDUSE kernel module would not touch (be aware of) the device specific
> configuration space. It should be more reasonable to fix it in the
> device driver. There is also some existing interface (.validate()) for
> doing that.

who is emulating the device configuration space ?

> And regardless of userspace device, we still need to fix it for other cases.

which cases ? Do you know that there is a buggy HW we need to workaround ?


> Thanks,
> Yongji