On Mon, Feb 15, 2021 at 04:23:54PM +0100, Greg KH wrote:
On Mon, Feb 15, 2021 at 04:03:21PM +0100, Stefano Garzarella wrote:
On Mon, Feb 15, 2021 at 03:32:19PM +0100, Greg KH wrote:
> On Thu, Feb 11, 2021 at 05:25:19PM +0100, Stefano Garzarella wrote:
> > Commit 65b709586e222fa6ffd4166ac7fdb5d5dad113ee upstream.
>
> No, this really is not that commit, so please do not say it is.
Oops, sorry.
>
> > Before this patch, if 'offset + len' was equal to
> > sizeof(struct virtio_net_config), the entire buffer wasn't filled,
> > returning incorrect values to the caller.
> >
> > Since 'vdpasim->config' type is 'struct virtio_net_config', we can
> > safely copy its content under this condition.
> >
> > Commit 65b709586e22 ("vdpa_sim: add get_config callback in
> > vdpasim_dev_attr") unintentionally solved it upstream while
> > refactoring vdpa_sim.c to support multiple devices. But we don't want
> > to backport it to stable branches as it contains many changes.
> >
> > Fixes: 2c53d0f64c06 ("vdpasim: vDPA device simulator")
> > Cc: <stable@xxxxxxxxxxxxxxx> # 5.10.x
> > Signed-off-by: Stefano Garzarella <sgarzare@xxxxxxxxxx>
> > ---
> > drivers/vdpa/vdpa_sim/vdpa_sim.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/vdpa/vdpa_sim/vdpa_sim.c b/drivers/vdpa/vdpa_sim/vdpa_sim.c
> > index 6a90fdb9cbfc..8ca178d7b02f 100644
> > --- a/drivers/vdpa/vdpa_sim/vdpa_sim.c
> > +++ b/drivers/vdpa/vdpa_sim/vdpa_sim.c
> > @@ -572,7 +572,7 @@ static void vdpasim_get_config(struct vdpa_device *vdpa, unsigned int offset,
> > {
> > struct vdpasim *vdpasim = vdpa_to_sim(vdpa);
> >
> > - if (offset + len < sizeof(struct virtio_net_config))
> > + if (offset + len <= sizeof(struct virtio_net_config))
> > memcpy(buf, (u8 *)&vdpasim->config + offset, len);
> > }
>
> I'll be glad to take a one-off patch, but why can't we take the real
> upstream patch? That is always the better long-term solution, right?
Because that patch depends on the following patches merged in v5.11-rc1
while refactoring vdpa_sim:
f37cbbc65178 vdpa_sim: make 'config' generic and usable for any device type
cf1a3b35382c vdpa_sim: store parsed MAC address in a buffer
a13b5918fdd0 vdpa_sim: add work_fn in vdpasim_dev_attr
011c35bac5ef vdpa_sim: add supported_features field in vdpasim_dev_attr
2f8f46188805 vdpa_sim: add device id field in vdpasim_dev_attr
6c6e28fe4579 vdpa_sim: add struct vdpasim_dev_attr for device attributes
36a9c3063025 vdpa_sim: rename vdpasim_config_ops variables
423248d60d2b vdpa_sim: remove hard-coded virtq count
Maybe we can skip some of them, but IMHO should be less risky to apply only
this change.
If you want I can try to figure out the minimum sub-set of patches needed
for 65b709586e22 ("vdpa_sim: add get_config callback in vdpasim_dev_attr").
The minimum is always nice :)
The minimum set, including the patch that fixes the issue, is the
following:
65b709586e22 vdpa_sim: add get_config callback in vdpasim_dev_attr
f37cbbc65178 vdpa_sim: make 'config' generic and usable for any device type
cf1a3b35382c vdpa_sim: store parsed MAC address in a buffer
6c6e28fe4579 vdpa_sim: add struct vdpasim_dev_attr for device attributes
423248d60d2b vdpa_sim: remove hard-coded virtq count
The patches apply fairly cleanly. There are a few contextual differences
due to the lack of the other patches:
$ git backport-diff -u master -r linux-5.10.y..HEAD
Key:
[----] : patches are identical
[####] : number of functional differences between upstream/downstream patch
[down] : patch is downstream-only
The flags [FC] indicate (F)unctional and (C)ontextual differences, respectively
001/5:[----] [--] 'vdpa_sim: remove hard-coded virtq count'
002/5:[----] [-C] 'vdpa_sim: add struct vdpasim_dev_attr for device attributes'
003/5:[----] [--] 'vdpa_sim: store parsed MAC address in a buffer'
004/5:[----] [-C] 'vdpa_sim: make 'config' generic and usable for any device type'
005/5:[----] [-C] 'vdpa_sim: add get_config callback in vdpasim_dev_attr'
If it's just too much churn for no good reason, then yes, the one-line
change above will be ok, but you need to document the heck out of why
this is not upstream and that it is a one-off thing.
Shortly I'll send the series to stable@xxxxxxxxxxxxxxx so you can judge
if it's okay or better to resend this patch with a better description.
Thanks
Stefano
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