Re: [PATCH net-next v2 2/7] um: vector: honor virtio net hdr conversion failures

["Michael S. Tsirkin" <mst@redhat.com>]

On Thu, Oct 15, 2026 at 02:47:01PM +0200, Johannes Berg wrote:
> On Thu, 2026-10-15 at 08:41 -0400, Michael S. Tsirkin wrote:
> > virtio_net_hdr_to_skb() refuses packets whose checksum metadata
> > it cannot make sense of, but the vector raw transport ignored
> > its return value: rejected packets went on into the stack with
> > their metadata unvalidated.
> > 
> > Propagate the failure.
> > 
> > Assisted-by: LLM
> > Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
> > ---
> >  arch/um/drivers/vector_transports.c | 4 +++-
> >  1 file changed, 3 insertions(+), 1 deletion(-)
> > 
> > diff --git a/arch/um/drivers/vector_transports.c b/arch/um/drivers/vector_transports.c
> > index e1fb2a76fdff..8b7548458663 100644
> > --- a/arch/um/drivers/vector_transports.c
> > +++ b/arch/um/drivers/vector_transports.c
> > @@ -210,7 +210,9 @@ static int raw_verify_header(
> >  		return 1;
> >  
> >  	skb_set_network_header(skb, ETH_HLEN);
> > -	virtio_net_hdr_to_skb(skb, vheader, virtio_legacy_is_little_endian());
> > +	if (virtio_net_hdr_to_skb(skb, vheader,
> > +			virtio_legacy_is_little_endian()) < 0)
> > +		return -1;
> >  	return 0;
> > 
> 
> Seems it'd be simpler to just
> 
> 	return virtio_net_hdr_to_skb(...);
> 
> As far as I can tell, the function only returns -EINVAL or 0 (never a
> positive value), and the caller only cares about negative (error) or
> positive (no checksum needed), so that'd be equivalent?
> 
> johannes

if raw_verify_header can safely return any errno - i did not want to
audit it.

-- 
MST