net: mipsnet: check transmit buffer size before sending
When processing MIPSnet I/O port write operation, it uses a transmit buffer tx_buffer[MAX_ETH_FRAME_SIZE=1514]. Two indices 's->tx_written' and 's->tx_count' are used to control data written to this buffer. If the two were to be equal before writing, it'd lead to an OOB write access beyond tx_buffer. Add check to avoid it. Reported-by: Li Qiang <qiang6-s@360.cn> Signed-off-by: Prasad J Pandit <pjp@fedoraproject.org> Signed-off-by: Jason Wang <jasowang@redhat.com>
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			@ -183,10 +183,12 @@ static void mipsnet_ioport_write(void *opaque, hwaddr addr,
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        break;
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    case MIPSNET_TX_DATA_BUFFER:
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        s->tx_buffer[s->tx_written++] = val;
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        if (s->tx_written == s->tx_count) {
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        if ((s->tx_written >= MAX_ETH_FRAME_SIZE)
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            || (s->tx_written == s->tx_count)) {
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            /* Send buffer. */
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            trace_mipsnet_send(s->tx_count);
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            qemu_send_packet(qemu_get_queue(s->nic), s->tx_buffer, s->tx_count);
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            trace_mipsnet_send(s->tx_written);
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            qemu_send_packet(qemu_get_queue(s->nic),
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                                s->tx_buffer, s->tx_written);
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            s->tx_count = s->tx_written = 0;
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            s->intctl |= MIPSNET_INTCTL_TXDONE;
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            s->busy = 1;
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