CVE-2024-49947 net: test for not too small csum_start in virtio_net_hdr_to_skb()

In the Linux kernel, the following vulnerability has been resolved: net: test for not too small csumstart in virtionethdrtoskb syzbot was able to trigger this warning 1, after injecting a malicious packet through afpacket, setting skb-csumstart and thus the transport header to an incorrect value...