+Laurent/Finn
On 11/24/20 10:24 AM, Mauro Matteo Cascella wrote:
> An integer underflow could occur during packet transmission due to 'tx_len'
> not
> being updated if SONIC_TFC register is set to zero. Check for negative
> 'tx_len'
> when removing existing FCS.
>
> RHBZ: https://bugzilla.redhat.com/show_bug.cgi?id=1899722
> Signed-off-by: Mauro Matteo Cascella <mcasc...@redhat.com>
> Reported-by: Gaoning Pan <p...@zju.edu.cn>
> ---
> hw/net/dp8393x.c | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/hw/net/dp8393x.c b/hw/net/dp8393x.c
> index 674b04b354..205c0decc5 100644
> --- a/hw/net/dp8393x.c
> +++ b/hw/net/dp8393x.c
> @@ -495,6 +495,10 @@ static void dp8393x_do_transmit_packets(dp8393xState *s)
> } else {
> /* Remove existing FCS */
> tx_len -= 4;
> + if (tx_len < 0) {
> + SONIC_ERROR("tx_len is %d\n", tx_len);
> + break;
> + }
> }
>
> if (s->regs[SONIC_RCR] & (SONIC_RCR_LB1 | SONIC_RCR_LB0)) {
>
Doesn't it make more sense to check 'tx_len >= 4'
and skip tx/rx when 'tx_len == 0'?
-- >8 --
@@ -488,25 +488,29 @@ static void
dp8393x_do_transmit_packets(dp8393xState *s)
}
}
- /* Handle Ethernet checksum */
- if (!(s->regs[SONIC_TCR] & SONIC_TCR_CRCI)) {
- /* Don't append FCS there, to look like slirp packets
- * which don't have one */
- } else {
- /* Remove existing FCS */
- tx_len -= 4;
+ if (tx_len >= 4) {
+ /* Handle Ethernet checksum */
+ if (!(s->regs[SONIC_TCR] & SONIC_TCR_CRCI)) {
+ /* Don't append FCS there, to look like slirp packets
+ * which don't have one */
+ } else {
+ /* Remove existing FCS */
+ tx_len -= 4;
+ }
}
- if (s->regs[SONIC_RCR] & (SONIC_RCR_LB1 | SONIC_RCR_LB0)) {
- /* Loopback */
- s->regs[SONIC_TCR] |= SONIC_TCR_CRSL;
- if (nc->info->can_receive(nc)) {
- s->loopback_packet = 1;
- nc->info->receive(nc, s->tx_buffer, tx_len);
+ if (tx_len > 0) {
+ if (s->regs[SONIC_RCR] & (SONIC_RCR_LB1 | SONIC_RCR_LB0)) {
+ /* Loopback */
+ s->regs[SONIC_TCR] |= SONIC_TCR_CRSL;
+ if (nc->info->can_receive(nc)) {
+ s->loopback_packet = 1;
+ nc->info->receive(nc, s->tx_buffer, tx_len);
+ }
+ } else {
+ /* Transmit packet */
+ qemu_send_packet(nc, s->tx_buffer, tx_len);
}
- } else {
- /* Transmit packet */
- qemu_send_packet(nc, s->tx_buffer, tx_len);
}
s->regs[SONIC_TCR] |= SONIC_TCR_PTX;
---
