iio: adxl372: Fix unsafe buffer attributes

commit ab0ee36e90f611f32c3a53afe9dc743de48138e2 upstream.

The iio_triggered_buffer_setup_ext() was changed by
commit 15097c7a1adc ("iio: buffer: wrap all buffer attributes into iio_dev_attr")
to silently expect that all attributes given in buffer_attrs array are
device-attributes. This expectation was not forced by the API - and some
drivers did register attributes created by IIO_CONST_ATTR().

The added attribute "wrapping" does not copy the pointer to stored
string constant and when the sysfs file is read the kernel will access
to invalid location.

Change the IIO_CONST_ATTRs from the driver to IIO_DEVICE_ATTR in order
to prevent the invalid memory access.

Signed-off-by: Matti Vaittinen <mazziesaccount@gmail.com>
Fixes: 15097c7a1adc ("iio: buffer: wrap all buffer attributes into iio_dev_attr")
Cc: <Stable@vger.kernel.org>
Link: https://lore.kernel.org/r/19158499623cdf7f9c5efae1f13c9f1a918ff75f.1664782676.git.mazziesaccount@gmail.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/iio/accel/adxl372.c b/drivers/iio/accel/adxl372.c
index fc95924..4a358f8 100644 (file)
--- a/drivers/iio/accel/adxl372.c
+++ b/drivers/iio/accel/adxl372.c
@@ -998,17 +998,30 @@ static ssize_t adxl372_get_fifo_watermark(struct device *dev,
        return sprintf(buf, "%d\n", st->watermark);
 }
 
-static IIO_CONST_ATTR(hwfifo_watermark_min, "1");
-static IIO_CONST_ATTR(hwfifo_watermark_max,
-                     __stringify(ADXL372_FIFO_SIZE));
+static ssize_t hwfifo_watermark_min_show(struct device *dev,
+                                        struct device_attribute *attr,
+                                        char *buf)
+{
+       return sysfs_emit(buf, "%s\n", "1");
+}
+
+static ssize_t hwfifo_watermark_max_show(struct device *dev,
+                                        struct device_attribute *attr,
+                                        char *buf)
+{
+       return sysfs_emit(buf, "%s\n", __stringify(ADXL372_FIFO_SIZE));
+}
+
+static IIO_DEVICE_ATTR_RO(hwfifo_watermark_min, 0);
+static IIO_DEVICE_ATTR_RO(hwfifo_watermark_max, 0);
 static IIO_DEVICE_ATTR(hwfifo_watermark, 0444,
                       adxl372_get_fifo_watermark, NULL, 0);
 static IIO_DEVICE_ATTR(hwfifo_enabled, 0444,
                       adxl372_get_fifo_enabled, NULL, 0);
 
 static const struct attribute *adxl372_fifo_attributes[] = {
-       &iio_const_attr_hwfifo_watermark_min.dev_attr.attr,
-       &iio_const_attr_hwfifo_watermark_max.dev_attr.attr,
+       &iio_dev_attr_hwfifo_watermark_min.dev_attr.attr,
+       &iio_dev_attr_hwfifo_watermark_max.dev_attr.attr,
        &iio_dev_attr_hwfifo_watermark.dev_attr.attr,
        &iio_dev_attr_hwfifo_enabled.dev_attr.attr,
        NULL,