Re: [PATCH] rpmsg: virtio: don't let virtio core to validate used length

[Jason Wang]

On Tue, Nov 23, 2021 at 10:15 AM Jason Wang <jasowang@xxxxxxxxxx> wrote:
>
> On Tue, Nov 23, 2021 at 12:08 AM Arnaud Pouliquen
> <arnaud.pouliquen@xxxxxxxxxxx> wrote:
> >
> > For RX virtqueue, the used length is validated in all the three paths
> > (big, small and mergeable). For control vq, we never tries to use used
> > length. So this patch forbids the core to validate the used length.
>
> If I understand the code correctly, the function that calls
> virtqueue_get_buf() ares:
>
> rpmsg_recv_done()
> get_a_tx_buf()
>
> So it looks to me like the above change log needs some tweak? (It
> looks like a copy from the virtio-net patch).
>
> The codes are fine.
>
> Thanks
>
> >
> > Without patch the rpmsg client sample does not work.


Btw, this probably uncovers a bug of the rpmsg device which needs to be fixed.

Thanks

> >
> > Fixes: 939779f5152d ("virtio_ring: validate used buffer length")
> >
> > Signed-off-by: Arnaud Pouliquen <arnaud.pouliquen@xxxxxxxxxxx>
> > Cc: Jason Wang <jasowang@xxxxxxxxxx>
> > Cc: Michael S. Tsirkin <mst@xxxxxxxxxx>
> > ---
> > base-commit: fa55b7dcdc43c1aa1ba12bca9d2dd4318c2a0dbf
> > ---
> >  drivers/rpmsg/virtio_rpmsg_bus.c | 1 +
> >  1 file changed, 1 insertion(+)
> >
> > diff --git a/drivers/rpmsg/virtio_rpmsg_bus.c b/drivers/rpmsg/virtio_rpmsg_bus.c
> > index 9c112aa65040..5f73f19c2c38 100644
> > --- a/drivers/rpmsg/virtio_rpmsg_bus.c
> > +++ b/drivers/rpmsg/virtio_rpmsg_bus.c
> > @@ -1054,6 +1054,7 @@ static struct virtio_driver virtio_ipc_driver = {
> >         .feature_table_size = ARRAY_SIZE(features),
> >         .driver.name    = KBUILD_MODNAME,
> >         .driver.owner   = THIS_MODULE,
> > +       .suppress_used_validation = true,
> >         .id_table       = id_table,
> >         .probe          = rpmsg_probe,
> >         .remove         = rpmsg_remove,
> > --
> > 2.17.1
> >