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

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Date:   Wed, 13 Oct 2021 08:51:36 -0400
From:   "Michael S. Tsirkin" <mst@...hat.com>
To:     Yongji Xie <xieyongji@...edance.com>
Cc:     Christoph Hellwig <hch@....de>, Jason Wang <jasowang@...hat.com>,
        Stefan Hajnoczi <stefanha@...hat.com>,
        virtualization <virtualization@...ts.linux-foundation.org>,
        linux-block@...r.kernel.org,
        linux-kernel <linux-kernel@...r.kernel.org>,
        Kevin Wolf <kwolf@...hat.com>, Jens Axboe <axboe@...nel.dk>
Subject: Re: [PATCH v5] virtio-blk: Add validation for block size in config
 space

On Wed, Oct 13, 2021 at 08:34:22PM +0800, Yongji Xie wrote:
> On Wed, Oct 13, 2021 at 8:21 PM Michael S. Tsirkin <mst@...hat.com> wrote:
> >
> > On Mon, Oct 11, 2021 at 01:40:41PM +0200, Christoph Hellwig wrote:
> > > On Tue, Oct 05, 2021 at 06:42:43AM -0400, Michael S. Tsirkin wrote:
> > > > Stefan also pointed out this duplicates the logic from
> > > >
> > > >         if (blksize < 512 || blksize > PAGE_SIZE || !is_power_of_2(blksize))
> > > >                 return -EINVAL;
> > > >
> > > >
> > > > and a bunch of other places.
> > > >
> > > >
> > > > Would it be acceptable for blk layer to validate the input
> > > > instead of having each driver do it's own thing?
> > > > Maybe inside blk_queue_logical_block_size?
> > >
> > > I'm pretty sure we want down that before.  Let's just add a helper
> > > just for that check for now as part of this series.  Actually validating
> > > in in blk_queue_logical_block_size seems like a good idea, but returning
> > > errors from that has a long tail.
> >
> > Xie Yongji, I think I will revert this patch for now - can you
> > please work out adding that helper and using it in virtio?
> >
> 
> Fine, I will do it.
> 
> Thanks,
> Yongji

Great, thanks! And while at it, pls research a bit more and mention
in the commit log what is the result of an illegal blk size?
Is it memory corruption? A catastrophic failure?
If it's one of these cases, then it's ok to just fail probe.

-- 
MST