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Date:   Mon, 3 Oct 2022 11:11:12 +0300
From:   Matti Vaittinen <mazziesaccount@gmail.com>
To:     Matti Vaittinen <mazziesaccount@gmail.com>,
        Matti Vaittinen <matti.vaittinen@fi.rohmeurope.com>
Cc:     Jonathan Cameron <jic23@kernel.org>,
        Lars-Peter Clausen <lars@metafoo.de>,
        Matti Vaittinen <mazziesaccount@gmail.com>,
        Alexandru Ardelean <alexandru.ardelean@analog.com>,
        Miquel Raynal <miquel.raynal@bootlin.com>,
        Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>,
        Miaoqian Lin <linmq006@gmail.com>,
        Uwe =?iso-8859-1?Q?Kleine-K=F6nig?= 
        <u.kleine-koenig@pengutronix.de>, linux-iio@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: [PATCH v3 03/10] iio: bmc150-accel-core: Fix unsafe buffer attributes
Message-ID: <cf8a56658fc38db8bed64f456d898f5ad5a2814f.1664782676.git.mazziesaccount@gmail.com>
References: <cover.1664782676.git.mazziesaccount@gmail.com>
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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")

---

v2 =3D> v3:
Split change to own patch for simpler fix backporting.
---
 drivers/iio/accel/bmc150-accel-core.c | 23 ++++++++++++++++++-----
 1 file changed, 18 insertions(+), 5 deletions(-)

diff --git a/drivers/iio/accel/bmc150-accel-core.c b/drivers/iio/accel/bmc1=
50-accel-core.c
index 57e8a8350cd1..92f8b139acce 100644
--- a/drivers/iio/accel/bmc150-accel-core.c
+++ b/drivers/iio/accel/bmc150-accel-core.c
@@ -925,17 +925,30 @@ static const struct iio_chan_spec_ext_info bmc150_acc=
el_ext_info[] =3D {
 	{ }
 };
=20
-static IIO_CONST_ATTR(hwfifo_watermark_min, "1");
-static IIO_CONST_ATTR(hwfifo_watermark_max,
-		      __stringify(BMC150_ACCEL_FIFO_LENGTH));
+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(BMC150_ACCEL_FIFO_LENGTH));
+}
+
+static IIO_DEVICE_ATTR_RO(hwfifo_watermark_min, 0);
+static IIO_DEVICE_ATTR_RO(hwfifo_watermark_max, 0);
 static IIO_DEVICE_ATTR(hwfifo_enabled, S_IRUGO,
 		       bmc150_accel_get_fifo_state, NULL, 0);
 static IIO_DEVICE_ATTR(hwfifo_watermark, S_IRUGO,
 		       bmc150_accel_get_fifo_watermark, NULL, 0);
=20
 static const struct attribute *bmc150_accel_fifo_attributes[] =3D {
-	&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,
--=20
2.37.3


--=20
Matti Vaittinen, Linux device drivers
ROHM Semiconductors, Finland SWDC
Kiviharjunlenkki 1E
90220 OULU
FINLAND

~~~ "I don't think so," said Rene Descartes. Just then he vanished ~~~
Simon says - in Latin please.
~~~ "non cogito me" dixit Rene Descarte, deinde evanescavit ~~~
Thanks to Simon Glass for the translation =3D]=20

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