static void pcnet_csr_writew(PCNetState *s, uint32_t rap, uint32_t new_value)
{
    uint16_t val = new_value;
#ifdef PCNET_DEBUG_CSR
    printf("pcnet_csr_writew rap=%d val=0x%04x\n", rap, val);
#endif
    switch (rap) {
    case 0:
        s->csr[0] &= ~(val & 0x7f00); /* Clear any interrupt flags */

        s->csr[0] = (s->csr[0] & ~0x0040) | (val & 0x0048);

        val = (val & 0x007f) | (s->csr[0] & 0x7f00);

        /* IFF STOP, STRT and INIT are set, clear STRT and INIT */
        if ((val&7) == 7)
          val &= ~3;

        if (!CSR_STOP(s) && (val & 4))
            pcnet_stop(s);

        if (!CSR_INIT(s) && (val & 1))
            pcnet_init(s);

        if (!CSR_STRT(s) && (val & 2))
            pcnet_start(s);

        if (CSR_TDMD(s))
            pcnet_transmit(s);

        return;
    case 1:
    case 2:
    case 8:
    case 9:
    case 10:
    case 11:
    case 12:
    case 13:
    case 14:
    case 15:
    case 18: /* CRBAL */
    case 19: /* CRBAU */
    case 20: /* CXBAL */
    case 21: /* CXBAU */
    case 22: /* NRBAU */
    case 23: /* NRBAU */
    case 24:
    case 25:
    case 26:
    case 27:
    case 28:
    case 29:
    case 30:
    case 31:
    case 32:
    case 33:
    case 34:
    case 35:
    case 36:
    case 37:
    case 38:
    case 39:
    case 40: /* CRBC */
    case 41:
    case 42: /* CXBC */
    case 43:
    case 44:
    case 45:
    case 46: /* POLL */
    case 47: /* POLLINT */
    case 72:
    case 74:
    case 76: /* RCVRL */
    case 78: /* XMTRL */
    case 112:
       if (CSR_STOP(s) || CSR_SPND(s))
           break;
       return;
    case 3:
        break;
    case 4:
        s->csr[4] &= ~(val & 0x026a);
        val &= ~0x026a; val |= s->csr[4] & 0x026a;
        break;
    case 5:
        s->csr[5] &= ~(val & 0x0a90);
        val &= ~0x0a90; val |= s->csr[5] & 0x0a90;
        break;
    case 16:
        pcnet_csr_writew(s,1,val);
        return;
    case 17:
        pcnet_csr_writew(s,2,val);
        return;
    case 58:
        pcnet_bcr_writew(s,BCR_SWS,val);
        break;
    default:
        return;
    }
    s->csr[rap] = val;
}

The product performs operations on a memory buffer, but it reads from or writes to a memory location outside the buffer's intended boundary. This may result in read or write operations on unexpected memory locations that could be linked to other variables, data structures, or internal program data.