static uint16_t tsc2102_data_register_read(TSC210xState *s, int reg)
{
    switch (reg) {
    case 0x00:	/* X */
        s->dav &= 0xfbff;
        return TSC_CUT_RESOLUTION(X_TRANSFORM(s), s->precision) +
                (s->noise & 3);

    case 0x01:	/* Y */
        s->noise ++;
        s->dav &= 0xfdff;
        return TSC_CUT_RESOLUTION(Y_TRANSFORM(s), s->precision) ^
                (s->noise & 3);

    case 0x02:	/* Z1 */
        s->dav &= 0xfeff;
        return TSC_CUT_RESOLUTION(Z1_TRANSFORM(s), s->precision) -
                (s->noise & 3);

    case 0x03:	/* Z2 */
        s->dav &= 0xff7f;
        return TSC_CUT_RESOLUTION(Z2_TRANSFORM(s), s->precision) |
                (s->noise & 3);

    case 0x04:	/* KPData */
        if ((s->model & 0xff00) == 0x2300) {
            if (s->kb.intr && (s->kb.mode & 2)) {
                s->kb.intr = 0;
                qemu_irq_raise(s->kbint);
            }
            return s->kb.down;
        }

        return 0xffff;

    case 0x05:	/* BAT1 */
        s->dav &= 0xffbf;
        return TSC_CUT_RESOLUTION(BAT1_VAL, s->precision) +
                (s->noise & 6);

    case 0x06:	/* BAT2 */
        s->dav &= 0xffdf;
        return TSC_CUT_RESOLUTION(BAT2_VAL, s->precision);

    case 0x07:	/* AUX1 */
        s->dav &= 0xffef;
        return TSC_CUT_RESOLUTION(AUX1_VAL, s->precision);

    case 0x08:	/* AUX2 */
        s->dav &= 0xfff7;
        return 0xffff;

    case 0x09:	/* TEMP1 */
        s->dav &= 0xfffb;
        return TSC_CUT_RESOLUTION(TEMP1_VAL, s->precision) -
                (s->noise & 5);

    case 0x0a:	/* TEMP2 */
        s->dav &= 0xfffd;
        return TSC_CUT_RESOLUTION(TEMP2_VAL, s->precision) ^
                (s->noise & 3);

    case 0x0b:	/* DAC */
        s->dav &= 0xfffe;
        return 0xffff;

    default:
#ifdef TSC_VERBOSE
        fprintf(stderr, "tsc2102_data_register_read: "
                        "no such register: 0x%02x\n", reg);
#endif
        return 0xffff;
    }
}

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.