RE: [EXTERNAL] Re: [PATCH v3,net] virtio_net: Improve RSS key size validation

[Srujana Challa <schalla@marvell.com>]

> On Thu, Feb 12, 2026 at 06:33:40PM +0530, Srujana Challa wrote:
> > Replace hardcoded RSS max key size limit with a type based definition.
> > Add validation for RSS key size against spec minimum (40 bytes). When
> > validation fails, gracefully disable RSS features and continue
> > initialization rather than failing completely.
> >
> > Cc: stable@vger.kernel.org
> > Fixes: 3f7d9c1964fc ("virtio_net: Add hash_key_length check")
> > Signed-off-by: Srujana Challa <schalla@marvell.com>
> >
> > v3:
> > - Moved RSS key validation checks to virtnet_validate.
> > - Add fixes: tag and CC -stable
> > ---
> >  drivers/net/virtio_net.c | 29 +++++++++++++++++++++--------
> >  1 file changed, 21 insertions(+), 8 deletions(-)
> >
> > diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c index
> > db88dcaefb20..e61cea50dcab 100644
> > --- a/drivers/net/virtio_net.c
> > +++ b/drivers/net/virtio_net.c
> > @@ -381,7 +381,9 @@ struct receive_queue {
> >  	struct xdp_buff **xsk_buffs;
> >  };
> >
> > -#define VIRTIO_NET_RSS_MAX_KEY_SIZE     40
> > +#define VIRTIO_NET_RSS_MAX_KEY_SIZE \
> > +	(type_max(((struct virtio_net_config *)0)->rss_max_key_size) + 1)
> 
> +1 here really unintuitive.
> It does not look like it's still used, though?
It is still used for the rss_hash_key_data[VIRTIO_NET_RSS_MAX_KEY_SIZE] in struct virtnet_info.
Should I change it to use NETDEV_RSS_KEY_LEN?
> 
> 
> > +#define VIRTIO_NET_RSS_MIN_KEY_SIZE 40
> >
> >  /* Control VQ buffers: protected by the rtnl lock */  struct
> > control_buf { @@ -6627,6 +6629,24 @@ static int
> > virtnet_validate(struct virtio_device *vdev)
> >  		__virtio_clear_bit(vdev, VIRTIO_NET_F_STANDBY);
> >  	}
> >
> > +	if (virtio_has_feature(vdev, VIRTIO_NET_F_RSS) ||
> > +	    virtio_has_feature(vdev, VIRTIO_NET_F_HASH_REPORT)) {
> > +		u8 key_sz = virtio_cread8(vdev,
> > +					  offsetof(struct virtio_net_config,
> > +						   rss_max_key_size));
> > +		/* Spec requires at least 40 bytes */
> 
> move the define here then?
Will move.
> 
> > +		if (key_sz < VIRTIO_NET_RSS_MIN_KEY_SIZE) {
> > +			dev_warn(&vdev->dev,
> > +				 "rss_max_key_size=%u is less than spec
> minimum %u, disabling RSS\n",
> > +				 key_sz, VIRTIO_NET_RSS_MIN_KEY_SIZE);
> > +			if (virtio_has_feature(vdev, VIRTIO_NET_F_RSS))
> > +				__virtio_clear_bit(vdev, VIRTIO_NET_F_RSS);
> > +			if (virtio_has_feature(vdev,
> VIRTIO_NET_F_HASH_REPORT))
> > +				__virtio_clear_bit(vdev,
> > +
> VIRTIO_NET_F_HASH_REPORT);
> 
> 
> why not clear them unconditionally?
> 
> > +		}
> > +	}
> > +
> >  	return 0;
> >  }
> >
> > @@ -6839,13 +6859,6 @@ static int virtnet_probe(struct virtio_device
> *vdev)
> >  	if (vi->has_rss || vi->has_rss_hash_report) {
> >  		vi->rss_key_size =
> >  			virtio_cread8(vdev, offsetof(struct virtio_net_config,
> rss_max_key_size));
> > -		if (vi->rss_key_size > VIRTIO_NET_RSS_MAX_KEY_SIZE) {
> > -			dev_err(&vdev->dev, "rss_max_key_size=%u exceeds
> the limit %u.\n",
> > -				vi->rss_key_size,
> VIRTIO_NET_RSS_MAX_KEY_SIZE);
> > -			err = -EINVAL;
> > -			goto free;
> > -		}
> > -
> >  		vi->rss_hash_types_supported =
> >  		    virtio_cread32(vdev, offsetof(struct virtio_net_config,
> supported_hash_types));
> >  		vi->rss_hash_types_supported &=
> > --
> > 2.25.1