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![Jonathan Cameron](/assets/img/avatar_default.png)
One of a class of bugs pointed out by Lars in a recent review.
iio_push_to_buffers_with_timestamp assumes the buffer used is aligned
to the size of the timestamp (8 bytes). This is not guaranteed in
this driver which uses an array of smaller elements on the stack.
As Lars also noted this anti pattern can involve a leak of data to
userspace and that indeed can happen here. We close both issues by
moving to a suitable structure in the iio_priv() data.
This data is allocated with kzalloc so no data can leak apart
from previous readings.
The explicit alignment of ts is necessary to ensure correct padding
on architectures where s64 is only 4 bytes aligned such as x86_32.
Fixes: a9e9c7153e
("iio: adc: add max1117/max1118/max1119 ADC driver")
Reported-by: Lars-Peter Clausen <lars@metafoo.de>
Cc: Akinobu Mita <akinobu.mita@gmail.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Cc: <Stable@vger.kernel.org>
309 lines
6.9 KiB
C
309 lines
6.9 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* MAX1117/MAX1118/MAX1119 8-bit, dual-channel ADCs driver
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*
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* Copyright (c) 2017 Akinobu Mita <akinobu.mita@gmail.com>
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*
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* Datasheet: https://datasheets.maximintegrated.com/en/ds/MAX1117-MAX1119.pdf
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*
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* SPI interface connections
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*
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* SPI MAXIM
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* Master Direction MAX1117/8/9
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* ------ --------- -----------
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* nCS --> CNVST
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* SCK --> SCLK
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* MISO <-- DOUT
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* ------ --------- -----------
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*/
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#include <linux/module.h>
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#include <linux/mod_devicetable.h>
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#include <linux/spi/spi.h>
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#include <linux/iio/iio.h>
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#include <linux/iio/buffer.h>
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#include <linux/iio/triggered_buffer.h>
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#include <linux/iio/trigger_consumer.h>
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#include <linux/regulator/consumer.h>
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enum max1118_id {
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max1117,
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max1118,
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max1119,
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};
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struct max1118 {
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struct spi_device *spi;
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struct mutex lock;
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struct regulator *reg;
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/* Ensure natural alignment of buffer elements */
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struct {
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u8 channels[2];
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s64 ts __aligned(8);
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} scan;
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u8 data ____cacheline_aligned;
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};
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#define MAX1118_CHANNEL(ch) \
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{ \
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.type = IIO_VOLTAGE, \
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.indexed = 1, \
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.channel = (ch), \
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.info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
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.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \
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.scan_index = ch, \
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.scan_type = { \
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.sign = 'u', \
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.realbits = 8, \
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.storagebits = 8, \
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}, \
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}
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static const struct iio_chan_spec max1118_channels[] = {
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MAX1118_CHANNEL(0),
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MAX1118_CHANNEL(1),
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IIO_CHAN_SOFT_TIMESTAMP(2),
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};
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static int max1118_read(struct spi_device *spi, int channel)
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{
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struct iio_dev *indio_dev = spi_get_drvdata(spi);
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struct max1118 *adc = iio_priv(indio_dev);
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struct spi_transfer xfers[] = {
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/*
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* To select CH1 for conversion, CNVST pin must be brought high
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* and low for a second time.
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*/
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{
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.len = 0,
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.delay = { /* > CNVST Low Time 100 ns */
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.value = 1,
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.unit = SPI_DELAY_UNIT_USECS
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},
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.cs_change = 1,
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},
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/*
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* The acquisition interval begins with the falling edge of
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* CNVST. The total acquisition and conversion process takes
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* <7.5us.
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*/
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{
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.len = 0,
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.delay = {
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.value = 8,
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.unit = SPI_DELAY_UNIT_USECS
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},
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},
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{
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.rx_buf = &adc->data,
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.len = 1,
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},
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};
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int ret;
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if (channel == 0)
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ret = spi_sync_transfer(spi, xfers + 1, 2);
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else
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ret = spi_sync_transfer(spi, xfers, 3);
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if (ret)
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return ret;
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return adc->data;
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}
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static int max1118_get_vref_mV(struct spi_device *spi)
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{
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struct iio_dev *indio_dev = spi_get_drvdata(spi);
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struct max1118 *adc = iio_priv(indio_dev);
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const struct spi_device_id *id = spi_get_device_id(spi);
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int vref_uV;
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switch (id->driver_data) {
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case max1117:
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return 2048;
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case max1119:
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return 4096;
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case max1118:
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vref_uV = regulator_get_voltage(adc->reg);
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if (vref_uV < 0)
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return vref_uV;
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return vref_uV / 1000;
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}
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return -ENODEV;
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}
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static int max1118_read_raw(struct iio_dev *indio_dev,
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struct iio_chan_spec const *chan,
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int *val, int *val2, long mask)
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{
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struct max1118 *adc = iio_priv(indio_dev);
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switch (mask) {
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case IIO_CHAN_INFO_RAW:
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mutex_lock(&adc->lock);
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*val = max1118_read(adc->spi, chan->channel);
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mutex_unlock(&adc->lock);
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if (*val < 0)
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return *val;
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return IIO_VAL_INT;
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case IIO_CHAN_INFO_SCALE:
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*val = max1118_get_vref_mV(adc->spi);
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if (*val < 0)
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return *val;
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*val2 = 8;
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return IIO_VAL_FRACTIONAL_LOG2;
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}
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return -EINVAL;
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}
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static const struct iio_info max1118_info = {
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.read_raw = max1118_read_raw,
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};
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static irqreturn_t max1118_trigger_handler(int irq, void *p)
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{
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struct iio_poll_func *pf = p;
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struct iio_dev *indio_dev = pf->indio_dev;
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struct max1118 *adc = iio_priv(indio_dev);
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int scan_index;
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int i = 0;
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mutex_lock(&adc->lock);
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for_each_set_bit(scan_index, indio_dev->active_scan_mask,
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indio_dev->masklength) {
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const struct iio_chan_spec *scan_chan =
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&indio_dev->channels[scan_index];
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int ret = max1118_read(adc->spi, scan_chan->channel);
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if (ret < 0) {
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dev_warn(&adc->spi->dev,
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"failed to get conversion data\n");
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goto out;
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}
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adc->scan.channels[i] = ret;
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i++;
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}
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iio_push_to_buffers_with_timestamp(indio_dev, &adc->scan,
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iio_get_time_ns(indio_dev));
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out:
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mutex_unlock(&adc->lock);
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iio_trigger_notify_done(indio_dev->trig);
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return IRQ_HANDLED;
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}
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static int max1118_probe(struct spi_device *spi)
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{
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struct iio_dev *indio_dev;
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struct max1118 *adc;
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const struct spi_device_id *id = spi_get_device_id(spi);
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int ret;
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indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*adc));
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if (!indio_dev)
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return -ENOMEM;
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adc = iio_priv(indio_dev);
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adc->spi = spi;
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mutex_init(&adc->lock);
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if (id->driver_data == max1118) {
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adc->reg = devm_regulator_get(&spi->dev, "vref");
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if (IS_ERR(adc->reg)) {
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dev_err(&spi->dev, "failed to get vref regulator\n");
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return PTR_ERR(adc->reg);
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}
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ret = regulator_enable(adc->reg);
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if (ret)
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return ret;
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}
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spi_set_drvdata(spi, indio_dev);
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indio_dev->name = spi_get_device_id(spi)->name;
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indio_dev->info = &max1118_info;
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indio_dev->modes = INDIO_DIRECT_MODE;
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indio_dev->channels = max1118_channels;
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indio_dev->num_channels = ARRAY_SIZE(max1118_channels);
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/*
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* To reinitiate a conversion on CH0, it is necessary to allow for a
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* conversion to be complete and all of the data to be read out. Once
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* a conversion has been completed, the MAX1117/MAX1118/MAX1119 will go
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* into AutoShutdown mode until the next conversion is initiated.
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*/
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max1118_read(spi, 0);
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ret = iio_triggered_buffer_setup(indio_dev, NULL,
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max1118_trigger_handler, NULL);
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if (ret)
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goto err_reg_disable;
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ret = iio_device_register(indio_dev);
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if (ret)
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goto err_buffer_cleanup;
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return 0;
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err_buffer_cleanup:
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iio_triggered_buffer_cleanup(indio_dev);
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err_reg_disable:
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if (id->driver_data == max1118)
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regulator_disable(adc->reg);
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return ret;
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}
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static int max1118_remove(struct spi_device *spi)
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{
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struct iio_dev *indio_dev = spi_get_drvdata(spi);
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struct max1118 *adc = iio_priv(indio_dev);
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const struct spi_device_id *id = spi_get_device_id(spi);
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iio_device_unregister(indio_dev);
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iio_triggered_buffer_cleanup(indio_dev);
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if (id->driver_data == max1118)
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return regulator_disable(adc->reg);
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return 0;
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}
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static const struct spi_device_id max1118_id[] = {
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{ "max1117", max1117 },
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{ "max1118", max1118 },
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{ "max1119", max1119 },
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{}
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};
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MODULE_DEVICE_TABLE(spi, max1118_id);
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static const struct of_device_id max1118_dt_ids[] = {
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{ .compatible = "maxim,max1117" },
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{ .compatible = "maxim,max1118" },
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{ .compatible = "maxim,max1119" },
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{},
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};
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MODULE_DEVICE_TABLE(of, max1118_dt_ids);
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static struct spi_driver max1118_spi_driver = {
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.driver = {
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.name = "max1118",
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.of_match_table = max1118_dt_ids,
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},
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.probe = max1118_probe,
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.remove = max1118_remove,
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.id_table = max1118_id,
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};
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module_spi_driver(max1118_spi_driver);
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MODULE_AUTHOR("Akinobu Mita <akinobu.mita@gmail.com>");
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MODULE_DESCRIPTION("MAXIM MAX1117/MAX1118/MAX1119 ADCs driver");
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MODULE_LICENSE("GPL v2");
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