Bug 1332106

An infinite loop vulnerability in e1000_receive_iov() function was found.

Vulnerable code (hw/net/e1000.c):

static ssize_t
e1000_receive_iov(NetClientState *nc, const struct iovec *iov, int iovcnt)
{
...
do {
desc_size = total_size - desc_offset;
if (desc_size > s->rxbuf_size) {
desc_size = s->rxbuf_size;
}
base = rx_desc_base(s) + sizeof(desc) * s->mac_reg[RDH];// we can set base
pci_dma_read(d, base, &desc, sizeof(desc));
desc.special = vlan_special;
desc.status |= (vlan_status | E1000_RXD_STAT_DD);
if (desc.buffer_addr) {// set desc.buffer_addr = NULL
...
} else { // as per intel docs; skip descriptors with null buf addr
DBGOUT(RX, "Null RX descriptor!!\n");
}
pci_dma_write(d, base, &desc, sizeof(desc));

if (++s->mac_reg[RDH] * sizeof(desc) >= s->mac_reg[RDLEN])//set this always to be true
s->mac_reg[RDH] = 0;
/* see comment in start_xmit; same here */
if (s->mac_reg[RDH] == rdh_start) {
DBGOUT(RXERR, "RDH wraparound @%x, RDT %x, RDLEN %x\n",
rdh_start, s->mac_reg[RDT], s->mac_reg[RDLEN]);
set_ics(s, 0, E1000_ICS_RXO);
return -1;
}
} while (desc_offset < total_size);// desc_offset will always be 0, infinite loop
...
return size;
}

By setting desc.buffer_addr = NULL, lot of statements are to be ignored and by setting s->mac_reg[RDH], s->mac_reg[RDLEN] and some other variables properly, infinite loop in do while cycle can be reached.