spi_sync call uses its spi_message parameter to keep completion information,
using a drvdata structure is not thread-safe, potentially causing one thread
having pointers to memory on or above other threads stack. use mutex to
prevent multiple access
Signed-off-by: Pavel Herrmann <morpheus.ibis@xxxxxxxxx>
Acked-by: Russell King <rmk+kernel@xxxxxxxxxxxxxxxx>
Acked-by: Pavel Machek <pavel@xxxxxx>
Acked-by: Marek Vasut <marek.vasut@xxxxxxxxx>
Acked-by: Cyril Hrubis <metan@xxxxxx>
Tested-by: Stanislav Brabec <utx@xxxxxxxxxx>
---
drivers/hwmon/max1111.c | 11 +++++++++++
1 files changed, 11 insertions(+), 0 deletions(-)
diff --git a/drivers/hwmon/max1111.c b/drivers/hwmon/max1111.c
index 12a54aa..5c9e54c 100644
--- a/drivers/hwmon/max1111.c
+++ b/drivers/hwmon/max1111.c
@@ -40,6 +40,8 @@ struct max1111_data {
struct spi_transfer xfer[2];
uint8_t *tx_buf;
uint8_t *rx_buf;
+ struct mutex drvdata_lock;
+ /* protect msg, xfer and buffers from multiple access */
};
static int max1111_read(struct device *dev, int channel)
@@ -48,6 +50,9 @@ static int max1111_read(struct device *dev, int channel)
uint8_t v1, v2;
int err;
+ /* writing to drvdata struct is not thread safe, wait on mutex */
+ mutex_lock(&data->drvdata_lock);
+
data->tx_buf[0] = (channel << MAX1111_CTRL_SEL_SH) |
MAX1111_CTRL_PD0 | MAX1111_CTRL_PD1 |
MAX1111_CTRL_SGL | MAX1111_CTRL_UNI | MAX1111_CTRL_STR;
@@ -55,12 +60,15 @@ static int max1111_read(struct device *dev, int channel)
err = spi_sync(data->spi, &data->msg);
if (err < 0) {
dev_err(dev, "spi_sync failed with %d\n", err);
+ mutex_unlock(&data->drvdata_lock);
return err;
}
v1 = data->rx_buf[0];
v2 = data->rx_buf[1];
+ mutex_unlock(&data->drvdata_lock);
+
if ((v1 & 0xc0) || (v2 & 0x3f))
return -EINVAL;
@@ -176,6 +184,8 @@ static int __devinit max1111_probe(struct spi_device *spi)
if (err)
goto err_free_data;
+ mutex_init(&data->drvdata_lock);
+
data->spi = spi;
spi_set_drvdata(spi, data);
@@ -213,6 +223,7 @@ static int __devexit max1111_remove(struct spi_device *spi)
hwmon_device_unregister(data->hwmon_dev);
sysfs_remove_group(&spi->dev.kobj, &max1111_attr_group);
+ mutex_destroy(data->drvdata_lock);
kfree(data->rx_buf);
kfree(data->tx_buf);
kfree(data);
--
1.7.5.rc3
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