static int qeth_check_idx_response(struct qeth_card *card,
	unsigned char *buffer)
{
	if (!buffer)
		return 0;

	QETH_DBF_HEX(CTRL, 2, buffer, QETH_DBF_CTRL_LEN);
	if ((buffer[2] & 0xc0) == 0xc0) {
		QETH_DBF_MESSAGE(2, "received an IDX TERMINATE "
			   "with cause code 0x%02x%s\n",
			   buffer[4],
			   ((buffer[4] == 0x22) ?
			    " -- try another portname" : ""));
		QETH_CARD_TEXT(card, 2, "ckidxres");
		QETH_CARD_TEXT(card, 2, " idxterm");
		QETH_CARD_TEXT_(card, 2, "  rc%d", -EIO);
		if (buffer[4] == 0xf6) {
			dev_err(&card->gdev->dev,
			"The qeth device is not configured "
			"for the OSI layer required by z/VM\n");
			return -EPERM;
		}
		return -EIO;
	}
	return 0;
}

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.