This is a note to let you know that I've just added the patch titled
hwmon: (max1111) Fix race condition causing NULL pointer exception
to the 2.6.39-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
hwmon-max1111-fix-race-condition-causing-null-pointer-exception.patch
and it can be found in the queue-2.6.39 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <[email protected]> know about it.
>From d3f684f2820a7f42acef68bea6622d9032127fb2 Mon Sep 17 00:00:00 2001
From: Pavel Herrmann <[email protected]>
Date: Sun, 17 Jul 2011 18:39:19 +0200
Subject: hwmon: (max1111) Fix race condition causing NULL pointer exception
From: Pavel Herrmann <[email protected]>
commit d3f684f2820a7f42acef68bea6622d9032127fb2 upstream.
spi_sync call uses its spi_message parameter to keep completion information,
using a drvdata structure is not thread-safe. Use a mutex to prevent
multiple access to shared driver data.
Signed-off-by: Pavel Herrmann <[email protected]>
Acked-by: Russell King <[email protected]>
Acked-by: Pavel Machek <[email protected]>
Acked-by: Marek Vasut <[email protected]>
Acked-by: Cyril Hrubis <[email protected]>
Tested-by: Stanislav Brabec <[email protected]>
Signed-off-by: Jean Delvare <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
drivers/hwmon/max1111.c | 11 +++++++++++
1 file changed, 11 insertions(+)
--- 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 *d
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 *d
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(struc
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(stru
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);
Patches currently in stable-queue which might be from [email protected]
are
queue-2.6.39/hwmon-max1111-fix-race-condition-causing-null-pointer-exception.patch
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