[PATCH net 0/2] tap/tun: harden by dropping short frame

[Dongli Zhang <dongli.zhang@xxxxxxxxxx>]

This is to harden all of tap/tun to avoid any short frame smaller than the
Ethernet header (ETH_HLEN).

While the xen-netback already rejects short frame smaller than ETH_HLEN ...

 914 static void xenvif_tx_build_gops(struct xenvif_queue *queue,
 915                                      int budget,
 916                                      unsigned *copy_ops,
 917                                      unsigned *map_ops)
 918 {
... ...
1007                 if (unlikely(txreq.size < ETH_HLEN)) {
1008                         netdev_dbg(queue->vif->dev,
1009                                    "Bad packet size: %d\n", txreq.size);
1010                         xenvif_tx_err(queue, &txreq, extra_count, idx);
1011                         break;
1012                 }

... the short frame may not be dropped by vhost-net/tap/tun.

This fixes CVE-2024-41090 and CVE-2024-41091.

Thank you very much!

Dongli Zhang