e1000: switch to use qemu_receive_packet() for loopback

This patch switches to use qemu_receive_packet() which can detect
reentrancy and return early.

This is intended to address CVE-2021-3416.

Cc: Prasad J Pandit <ppandit@redhat.com>
Cc: qemu-stable@nongnu.org
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>

hw/net/e1000.c

@@ -546,7 +546,7 @@ e1000_send_packet(E1000State *s, const uint8_t *buf, int size)
 
     NetClientState *nc = qemu_get_queue(s->nic);
     if (s->phy_reg[PHY_CTRL] & MII_CR_LOOPBACK) {
-        nc->info->receive(nc, buf, size);
+        qemu_receive_packet(nc, buf, size);
     } else {
         qemu_send_packet(nc, buf, size);
     }