[PATCH v3 2/5] iio: consumers: copy/release available info from producer to fix race
From: Matteo Martelli
Date: Tue Oct 15 2024 - 07:07:26 EST
Consumers need to call the producer's read_avail_release_resource()
callback after reading producer's available info. To avoid a race
condition with the producer unregistration, change inkern
iio_channel_read_avail() so that it copies the available info from the
producer and immediately calls its release callback with info_exists
locked.
Also, modify the users of iio_read_avail_channel_raw() and
iio_read_avail_channel_attribute() to free the copied available buffers
after calling these functions.
Signed-off-by: Matteo Martelli <matteomartelli3@xxxxxxxxx>
---
drivers/iio/afe/iio-rescale.c | 8 ++++
drivers/iio/dac/dpot-dac.c | 8 ++++
drivers/iio/inkern.c | 68 ++++++++++++++++++++++++++--------
drivers/iio/multiplexer/iio-mux.c | 8 ++++
drivers/power/supply/ingenic-battery.c | 17 ++++++---
include/linux/iio/consumer.h | 4 +-
6 files changed, 90 insertions(+), 23 deletions(-)
diff --git a/drivers/iio/afe/iio-rescale.c b/drivers/iio/afe/iio-rescale.c
index 56e5913ab82d1c045c9ca27012008a4495502cbf..78bb86c291706748b4072a484532ad20c415ff9f 100644
--- a/drivers/iio/afe/iio-rescale.c
+++ b/drivers/iio/afe/iio-rescale.c
@@ -249,9 +249,17 @@ static int rescale_read_avail(struct iio_dev *indio_dev,
}
}
+static void rescale_read_avail_release_res(struct iio_dev *indio_dev,
+ struct iio_chan_spec const *chan,
+ const int *vals, long mask)
+{
+ kfree(vals);
+}
+
static const struct iio_info rescale_info = {
.read_raw = rescale_read_raw,
.read_avail = rescale_read_avail,
+ .read_avail_release_resource = rescale_read_avail_release_res,
};
static ssize_t rescale_read_ext_info(struct iio_dev *indio_dev,
diff --git a/drivers/iio/dac/dpot-dac.c b/drivers/iio/dac/dpot-dac.c
index f36f10bfb6be7863a56b911b5f58671ef530c977..43d68e17fc3a5fca59fad6ccf818eeadfecdb8c1 100644
--- a/drivers/iio/dac/dpot-dac.c
+++ b/drivers/iio/dac/dpot-dac.c
@@ -108,6 +108,13 @@ static int dpot_dac_read_avail(struct iio_dev *indio_dev,
return -EINVAL;
}
+static void dpot_dac_read_avail_release_res(struct iio_dev *indio_dev,
+ struct iio_chan_spec const *chan,
+ const int *vals, long mask)
+{
+ kfree(vals);
+}
+
static int dpot_dac_write_raw(struct iio_dev *indio_dev,
struct iio_chan_spec const *chan,
int val, int val2, long mask)
@@ -125,6 +132,7 @@ static int dpot_dac_write_raw(struct iio_dev *indio_dev,
static const struct iio_info dpot_dac_info = {
.read_raw = dpot_dac_read_raw,
.read_avail = dpot_dac_read_avail,
+ .read_avail_release_resource = dpot_dac_read_avail_release_res,
.write_raw = dpot_dac_write_raw,
};
diff --git a/drivers/iio/inkern.c b/drivers/iio/inkern.c
index 7f325b3ed08fae6674245312cf8f57bb151006c0..7f50e33dc5084673aa66c25731add0c314cb477d 100644
--- a/drivers/iio/inkern.c
+++ b/drivers/iio/inkern.c
@@ -760,9 +760,29 @@ static int iio_channel_read_avail(struct iio_channel *chan,
if (!iio_channel_has_available(chan->channel, info))
return -EINVAL;
- if (iio_info->read_avail)
- return iio_info->read_avail(chan->indio_dev, chan->channel,
- vals, type, length, info);
+ if (iio_info->read_avail) {
+ const int *vals_tmp;
+ int ret;
+
+ ret = iio_info->read_avail(chan->indio_dev, chan->channel,
+ &vals_tmp, type, length, info);
+ if (ret < 0)
+ return ret;
+
+ /*
+ * Copy the producer's avail buffer with lock_exists locked to
+ * avoid possible race with producer unregistration.
+ */
+ *vals = kmemdup_array(vals_tmp, *length, sizeof(int), GFP_KERNEL);
+ if (!*vals)
+ return -ENOMEM;
+
+ if (iio_info->read_avail_release_resource)
+ iio_info->read_avail_release_resource(
+ chan->indio_dev, chan->channel, vals_tmp, info);
+
+ return ret;
+ }
return -EINVAL;
}
@@ -789,9 +809,11 @@ int iio_read_avail_channel_raw(struct iio_channel *chan,
ret = iio_read_avail_channel_attribute(chan, vals, &type, length,
IIO_CHAN_INFO_RAW);
- if (ret >= 0 && type != IIO_VAL_INT)
+ if (ret >= 0 && type != IIO_VAL_INT) {
/* raw values are assumed to be IIO_VAL_INT */
+ kfree(*vals);
ret = -EINVAL;
+ }
return ret;
}
@@ -820,24 +842,31 @@ static int iio_channel_read_max(struct iio_channel *chan,
if (val2)
*val2 = vals[5];
}
- return 0;
+ ret = 0;
+ break;
case IIO_AVAIL_LIST:
- if (length <= 0)
- return -EINVAL;
+ if (length <= 0) {
+ ret = -EINVAL;
+ goto out;
+ }
switch (*type) {
case IIO_VAL_INT:
*val = max_array(vals, length);
+ ret = 0;
break;
default:
/* TODO: learn about max for other iio values */
- return -EINVAL;
+ ret = -EINVAL;
}
- return 0;
+ break;
default:
- return -EINVAL;
+ ret = -EINVAL;
}
+out:
+ kfree(vals);
+ return ret;
}
int iio_read_max_channel_raw(struct iio_channel *chan, int *val)
@@ -876,24 +905,31 @@ static int iio_channel_read_min(struct iio_channel *chan,
if (val2)
*val2 = vals[1];
}
- return 0;
+ ret = 0;
+ break;
case IIO_AVAIL_LIST:
- if (length <= 0)
- return -EINVAL;
+ if (length <= 0) {
+ ret = -EINVAL;
+ goto out;
+ }
switch (*type) {
case IIO_VAL_INT:
*val = min_array(vals, length);
+ ret = 0;
break;
default:
/* TODO: learn about min for other iio values */
- return -EINVAL;
+ ret = -EINVAL;
}
- return 0;
+ break;
default:
- return -EINVAL;
+ ret = -EINVAL;
}
+out:
+ kfree(vals);
+ return ret;
}
int iio_read_min_channel_raw(struct iio_channel *chan, int *val)
diff --git a/drivers/iio/multiplexer/iio-mux.c b/drivers/iio/multiplexer/iio-mux.c
index 2953403bef53bbe47a97a8ab1c475ed88d7f86d2..31345437784b01c5d6f8ea70263f4c2574388e7a 100644
--- a/drivers/iio/multiplexer/iio-mux.c
+++ b/drivers/iio/multiplexer/iio-mux.c
@@ -142,6 +142,13 @@ static int mux_read_avail(struct iio_dev *indio_dev,
return ret;
}
+static void mux_read_avail_release_res(struct iio_dev *indio_dev,
+ struct iio_chan_spec const *chan,
+ const int *vals, long mask)
+{
+ kfree(vals);
+}
+
static int mux_write_raw(struct iio_dev *indio_dev,
struct iio_chan_spec const *chan,
int val, int val2, long mask)
@@ -171,6 +178,7 @@ static int mux_write_raw(struct iio_dev *indio_dev,
static const struct iio_info mux_info = {
.read_raw = mux_read_raw,
.read_avail = mux_read_avail,
+ .read_avail_release_resource = mux_read_avail_release_res,
.write_raw = mux_write_raw,
};
diff --git a/drivers/power/supply/ingenic-battery.c b/drivers/power/supply/ingenic-battery.c
index 0a40f425c27723ccec49985b8b5e14a737b6a7eb..3db000d9fff9a7a6819631314547b3d16db7f967 100644
--- a/drivers/power/supply/ingenic-battery.c
+++ b/drivers/power/supply/ingenic-battery.c
@@ -12,6 +12,7 @@
#include <linux/platform_device.h>
#include <linux/power_supply.h>
#include <linux/property.h>
+#include <linux/slab.h>
struct ingenic_battery {
struct device *dev;
@@ -79,8 +80,10 @@ static int ingenic_battery_set_scale(struct ingenic_battery *bat)
dev_err(bat->dev, "Unable to read channel avail scale\n");
return ret;
}
- if (ret != IIO_AVAIL_LIST || scale_type != IIO_VAL_FRACTIONAL_LOG2)
- return -EINVAL;
+ if (ret != IIO_AVAIL_LIST || scale_type != IIO_VAL_FRACTIONAL_LOG2) {
+ ret = -EINVAL;
+ goto out;
+ }
max_mV = bat->info->voltage_max_design_uv / 1000;
@@ -99,7 +102,8 @@ static int ingenic_battery_set_scale(struct ingenic_battery *bat)
if (best_idx < 0) {
dev_err(bat->dev, "Unable to find matching voltage scale\n");
- return -EINVAL;
+ ret = -EINVAL;
+ goto out;
}
/* Only set scale if there is more than one (fractional) entry */
@@ -109,10 +113,13 @@ static int ingenic_battery_set_scale(struct ingenic_battery *bat)
scale_raw[best_idx + 1],
IIO_CHAN_INFO_SCALE);
if (ret)
- return ret;
+ goto out;
}
- return 0;
+ ret = 0;
+out:
+ kfree(scale_raw);
+ return ret;
}
static enum power_supply_property ingenic_battery_properties[] = {
diff --git a/include/linux/iio/consumer.h b/include/linux/iio/consumer.h
index 333d1d8ccb37f387fe531577ac5e0bfc7f752cec..e3e268d2574b3e01c9412449d90d627de7efcd84 100644
--- a/include/linux/iio/consumer.h
+++ b/include/linux/iio/consumer.h
@@ -316,7 +316,7 @@ int iio_read_min_channel_raw(struct iio_channel *chan, int *val);
/**
* iio_read_avail_channel_raw() - read available raw values from a given channel
* @chan: The channel being queried.
- * @vals: Available values read back.
+ * @vals: Available values read back. Must be freed after use.
* @length: Number of entries in vals.
*
* Returns an error code, IIO_AVAIL_RANGE or IIO_AVAIL_LIST.
@@ -334,7 +334,7 @@ int iio_read_avail_channel_raw(struct iio_channel *chan,
/**
* iio_read_avail_channel_attribute() - read available channel attribute values
* @chan: The channel being queried.
- * @vals: Available values read back.
+ * @vals: Available values read back. Must be freed after use.
* @type: Type of values read back.
* @length: Number of entries in vals.
* @attribute: info attribute to be read back.
--
2.47.0