[PATCH 5.10 002/663] vdpa/mlx5: fix param validation in mlx5_vdpa_get_config()

[Greg Kroah-Hartman]

From: Stefano Garzarella <sgarzare@xxxxxxxxxx>

commit dcfde1635e764fd69cc756c7780d144e288608e9 upstream.

It's legal to have 'offset + len' equal to
sizeof(struct virtio_net_config), since 'ndev->config' is a
'struct virtio_net_config', so we can safely copy its content under
this condition.

Fixes: 1a86b377aa21 ("vdpa/mlx5: Add VDPA driver for supported mlx5 devices")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Stefano Garzarella <sgarzare@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20210208161741.104939-1-sgarzare@xxxxxxxxxx
Signed-off-by: Michael S. Tsirkin <mst@xxxxxxxxxx>
Acked-by: Jason Wang <jasowang@xxxxxxxxxx>
Acked-by: Eli Cohen <elic@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 drivers/vdpa/mlx5/net/mlx5_vnet.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/vdpa/mlx5/net/mlx5_vnet.c
+++ b/drivers/vdpa/mlx5/net/mlx5_vnet.c
@@ -1805,7 +1805,7 @@ static void mlx5_vdpa_get_config(struct
 	struct mlx5_vdpa_dev *mvdev = to_mvdev(vdev);
 	struct mlx5_vdpa_net *ndev = to_mlx5_vdpa_ndev(mvdev);
 
-	if (offset + len < sizeof(struct virtio_net_config))
+	if (offset + len <= sizeof(struct virtio_net_config))
 		memcpy(buf, (u8 *)&ndev->config + offset, len);
 }