patch "iio: adxl367: Fix unsafe buffer attributes" added to char-misc-linus

This is a note to let you know that I've just added the patch titled

iio: adxl367: Fix unsafe buffer attributes

to my char-misc git tree which can be found at
git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc.git
in the char-misc-linus branch.

The patch will show up in the next release of the linux-next tree (usually sometime within the next 24 hours during the week.)

The patch will hopefully also be merged in Linus's tree for the next -rc kernel release.

If you have any questions about this process, please let me know.

From 5e23b33d1e84f04c80da6f1d89cbb3d3a3f81e01 Mon Sep 17 00:00:00 2001
From: Matti Vaittinen <[email protected]>
Date: Mon, 3 Oct 2022 11:10:29 +0300
Subject: iio: adxl367: Fix unsafe buffer attributes

The devm_iio_kfifo_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.

---
 drivers/iio/accel/adxl367.c | 23 ++++++++++++++++++-----
 1 file changed, 18 insertions(+), 5 deletions(-)

index 47feb375b70b..7c7d78040793 100644
@@ -1185,17 +1185,30 @@ static ssize_t adxl367_get_fifo_watermark(struct device *dev,
 	return sysfs_emit(buf, "%d\n", fifo_watermark);
 }
 
-static IIO_CONST_ATTR(hwfifo_watermark_min, "1");
-static IIO_CONST_ATTR(hwfifo_watermark_max,
-		      __stringify(ADXL367_FIFO_MAX_WATERMARK));
+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(ADXL367_FIFO_MAX_WATERMARK));
+}
+
+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,
 		       adxl367_get_fifo_watermark, NULL, 0);
 static IIO_DEVICE_ATTR(hwfifo_enabled, 0444,
 		       adxl367_get_fifo_enabled, NULL, 0);
 
 static const struct attribute *adxl367_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,

2.38.1