* [PATCH] lm85: Bounds check to_sensor_dev_attr()->index usage
@ 2023-01-27 22:37 Kees Cook
2023-01-28 13:13 ` Guenter Roeck
0 siblings, 1 reply; 6+ messages in thread
From: Kees Cook @ 2023-01-27 22:37 UTC (permalink / raw)
To: Jean Delvare
Cc: Kees Cook, Guenter Roeck, linux-hwmon, linux-kernel, linux-hardening
The index into various register arrays was not bounds checked. Add
checking. Seen under GCC 13:
drivers/hwmon/lm85.c: In function 'pwm_auto_pwm_minctl_store':
drivers/hwmon/lm85.c:1110:26: warning: array subscript [0, 31] is outside array bounds of 'struct lm85_autofan[3]' [-Warray-bounds=]
1110 | if (data->autofan[nr].min_off)
| ~~~~~~~~~~~~~^~~~
drivers/hwmon/lm85.c:317:29: note: while referencing 'autofan'
317 | struct lm85_autofan autofan[3];
| ^~~~~~~
Cc: Jean Delvare <jdelvare@suse.com>
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: linux-hwmon@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
---
drivers/hwmon/lm85.c | 221 +++++++++++++++++++++++++++---------
include/linux/hwmon-sysfs.h | 2 +-
2 files changed, 167 insertions(+), 56 deletions(-)
diff --git a/drivers/hwmon/lm85.c b/drivers/hwmon/lm85.c
index 8d33c2484755..367a77660dda 100644
--- a/drivers/hwmon/lm85.c
+++ b/drivers/hwmon/lm85.c
@@ -552,29 +552,40 @@ static struct lm85_data *lm85_update_device(struct device *dev)
static ssize_t fan_show(struct device *dev, struct device_attribute *attr,
char *buf)
{
- int nr = to_sensor_dev_attr(attr)->index;
+ unsigned int nr = to_sensor_dev_attr(attr)->index;
struct lm85_data *data = lm85_update_device(dev);
- return sprintf(buf, "%d\n", FAN_FROM_REG(data->fan[nr]));
+ int val = 0;
+
+ if (nr < ARRAY_SIZE(data->fan))
+ val = FAN_FROM_REG(data->fan[nr]);
+ return sprintf(buf, "%d\n", val);
}
static ssize_t fan_min_show(struct device *dev, struct device_attribute *attr,
char *buf)
{
- int nr = to_sensor_dev_attr(attr)->index;
+ unsigned int nr = to_sensor_dev_attr(attr)->index;
struct lm85_data *data = lm85_update_device(dev);
- return sprintf(buf, "%d\n", FAN_FROM_REG(data->fan_min[nr]));
+ int val = 0;
+
+ if (nr < ARRAY_SIZE(data->fan_min))
+ val = FAN_FROM_REG(data->fan_min[nr]);
+ return sprintf(buf, "%d\n", val);
}
static ssize_t fan_min_store(struct device *dev,
struct device_attribute *attr, const char *buf,
size_t count)
{
- int nr = to_sensor_dev_attr(attr)->index;
+ unsigned int nr = to_sensor_dev_attr(attr)->index;
struct lm85_data *data = dev_get_drvdata(dev);
struct i2c_client *client = data->client;
unsigned long val;
int err;
+ if (nr >= ARRAY_SIZE(data->fan_min))
+ return -EINVAL;
+
err = kstrtoul(buf, 10, &val);
if (err)
return err;
@@ -683,20 +694,27 @@ static SENSOR_DEVICE_ATTR_RO(fan4_alarm, alarm, 13);
static ssize_t pwm_show(struct device *dev, struct device_attribute *attr,
char *buf)
{
- int nr = to_sensor_dev_attr(attr)->index;
+ unsigned int nr = to_sensor_dev_attr(attr)->index;
struct lm85_data *data = lm85_update_device(dev);
- return sprintf(buf, "%d\n", PWM_FROM_REG(data->pwm[nr]));
+ int val = 0;
+
+ if (nr < ARRAY_SIZE(data->pwm))
+ val = PWM_FROM_REG(data->pwm[nr]);
+ return sprintf(buf, "%d\n", val);
}
static ssize_t pwm_store(struct device *dev, struct device_attribute *attr,
const char *buf, size_t count)
{
- int nr = to_sensor_dev_attr(attr)->index;
+ unsigned int nr = to_sensor_dev_attr(attr)->index;
struct lm85_data *data = dev_get_drvdata(dev);
struct i2c_client *client = data->client;
unsigned long val;
int err;
+ if (nr >= ARRAY_SIZE(data->pwm))
+ return -EINVAL;
+
err = kstrtoul(buf, 10, &val);
if (err)
return err;
@@ -711,11 +729,12 @@ static ssize_t pwm_store(struct device *dev, struct device_attribute *attr,
static ssize_t pwm_enable_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
- int nr = to_sensor_dev_attr(attr)->index;
+ unsigned int nr = to_sensor_dev_attr(attr)->index;
struct lm85_data *data = lm85_update_device(dev);
- int pwm_zone, enable;
+ int pwm_zone = -1, enable;
- pwm_zone = ZONE_FROM_REG(data->autofan[nr].config);
+ if (nr < ARRAY_SIZE(data->autofan))
+ pwm_zone = ZONE_FROM_REG(data->autofan[nr].config);
switch (pwm_zone) {
case -1: /* PWM is always at 100% */
enable = 0;
@@ -734,13 +753,16 @@ static ssize_t pwm_enable_store(struct device *dev,
struct device_attribute *attr,
const char *buf, size_t count)
{
- int nr = to_sensor_dev_attr(attr)->index;
+ unsigned int nr = to_sensor_dev_attr(attr)->index;
struct lm85_data *data = dev_get_drvdata(dev);
struct i2c_client *client = data->client;
u8 config;
unsigned long val;
int err;
+ if (nr >= ARRAY_SIZE(data->autofan))
+ return -EINVAL;
+
err = kstrtoul(buf, 10, &val);
if (err)
return err;
@@ -777,10 +799,13 @@ static ssize_t pwm_enable_store(struct device *dev,
static ssize_t pwm_freq_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
- int nr = to_sensor_dev_attr(attr)->index;
+ unsigned int nr = to_sensor_dev_attr(attr)->index;
struct lm85_data *data = lm85_update_device(dev);
int freq;
+ if (nr >= ARRAY_SIZE(data->pwm_freq))
+ return -EINVAL;
+
if (IS_ADT7468_HFPWM(data))
freq = 22500;
else
@@ -794,12 +819,15 @@ static ssize_t pwm_freq_store(struct device *dev,
struct device_attribute *attr, const char *buf,
size_t count)
{
- int nr = to_sensor_dev_attr(attr)->index;
+ unsigned int nr = to_sensor_dev_attr(attr)->index;
struct lm85_data *data = dev_get_drvdata(dev);
struct i2c_client *client = data->client;
unsigned long val;
int err;
+ if (nr >= ARRAY_SIZE(data->pwm_freq))
+ return -EINVAL;
+
err = kstrtoul(buf, 10, &val);
if (err)
return err;
@@ -843,10 +871,13 @@ static SENSOR_DEVICE_ATTR_RW(pwm3_freq, pwm_freq, 2);
static ssize_t in_show(struct device *dev, struct device_attribute *attr,
char *buf)
{
- int nr = to_sensor_dev_attr(attr)->index;
+ unsigned int nr = to_sensor_dev_attr(attr)->index;
struct lm85_data *data = lm85_update_device(dev);
- return sprintf(buf, "%d\n", INSEXT_FROM_REG(nr, data->in[nr],
- data->in_ext[nr]));
+ int val = 0;
+
+ if (nr < ARRAY_SIZE(data->in))
+ val = INSEXT_FROM_REG(nr, data->in[nr], data->in_ext[nr]);
+ return sprintf(buf, "%d\n", val);
}
static ssize_t in_min_show(struct device *dev, struct device_attribute *attr,
@@ -854,18 +885,25 @@ static ssize_t in_min_show(struct device *dev, struct device_attribute *attr,
{
int nr = to_sensor_dev_attr(attr)->index;
struct lm85_data *data = lm85_update_device(dev);
- return sprintf(buf, "%d\n", INS_FROM_REG(nr, data->in_min[nr]));
+ int val = 0;
+
+ if (nr < ARRAY_SIZE(data->in_min))
+ val = INS_FROM_REG(nr, data->in_min[nr]);
+ return sprintf(buf, "%d\n", val);
}
static ssize_t in_min_store(struct device *dev, struct device_attribute *attr,
const char *buf, size_t count)
{
- int nr = to_sensor_dev_attr(attr)->index;
+ unsigned int nr = to_sensor_dev_attr(attr)->index;
struct lm85_data *data = dev_get_drvdata(dev);
struct i2c_client *client = data->client;
long val;
int err;
+ if (nr >= ARRAY_SIZE(data->in_min))
+ return -EINVAL;
+
err = kstrtol(buf, 10, &val);
if (err)
return err;
@@ -880,20 +918,27 @@ static ssize_t in_min_store(struct device *dev, struct device_attribute *attr,
static ssize_t in_max_show(struct device *dev, struct device_attribute *attr,
char *buf)
{
- int nr = to_sensor_dev_attr(attr)->index;
+ unsigned int nr = to_sensor_dev_attr(attr)->index;
struct lm85_data *data = lm85_update_device(dev);
- return sprintf(buf, "%d\n", INS_FROM_REG(nr, data->in_max[nr]));
+ int val = 0;
+
+ if (nr < ARRAY_SIZE(data->in_max))
+ val = INS_FROM_REG(nr, data->in_max[nr]);
+ return sprintf(buf, "%d\n", val);
}
static ssize_t in_max_store(struct device *dev, struct device_attribute *attr,
const char *buf, size_t count)
{
- int nr = to_sensor_dev_attr(attr)->index;
+ unsigned int nr = to_sensor_dev_attr(attr)->index;
struct lm85_data *data = dev_get_drvdata(dev);
struct i2c_client *client = data->client;
long val;
int err;
+ if (nr >= ARRAY_SIZE(data->in_max))
+ return -EINVAL;
+
err = kstrtol(buf, 10, &val);
if (err)
return err;
@@ -935,30 +980,40 @@ static SENSOR_DEVICE_ATTR_RW(in7_max, in_max, 7);
static ssize_t temp_show(struct device *dev, struct device_attribute *attr,
char *buf)
{
- int nr = to_sensor_dev_attr(attr)->index;
+ unsigned int nr = to_sensor_dev_attr(attr)->index;
struct lm85_data *data = lm85_update_device(dev);
- return sprintf(buf, "%d\n", TEMPEXT_FROM_REG(data->temp[nr],
- data->temp_ext[nr]));
+ int val = 0;
+
+ if (nr < ARRAY_SIZE(data->temp))
+ val = TEMPEXT_FROM_REG(data->temp[nr], data->temp_ext[nr]);
+ return sprintf(buf, "%d\n", val);
}
static ssize_t temp_min_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
- int nr = to_sensor_dev_attr(attr)->index;
+ unsigned int nr = to_sensor_dev_attr(attr)->index;
struct lm85_data *data = lm85_update_device(dev);
- return sprintf(buf, "%d\n", TEMP_FROM_REG(data->temp_min[nr]));
+ int val = 0;
+
+ if (nr < ARRAY_SIZE(data->temp_min))
+ val = TEMP_FROM_REG(data->temp_min[nr]);
+ return sprintf(buf, "%d\n", val);
}
static ssize_t temp_min_store(struct device *dev,
struct device_attribute *attr, const char *buf,
size_t count)
{
- int nr = to_sensor_dev_attr(attr)->index;
+ unsigned int nr = to_sensor_dev_attr(attr)->index;
struct lm85_data *data = dev_get_drvdata(dev);
struct i2c_client *client = data->client;
long val;
int err;
+ if (nr >= ARRAY_SIZE(data->temp_min))
+ return -EINVAL;
+
err = kstrtol(buf, 10, &val);
if (err)
return err;
@@ -976,21 +1031,28 @@ static ssize_t temp_min_store(struct device *dev,
static ssize_t temp_max_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
- int nr = to_sensor_dev_attr(attr)->index;
+ unsigned int nr = to_sensor_dev_attr(attr)->index;
struct lm85_data *data = lm85_update_device(dev);
- return sprintf(buf, "%d\n", TEMP_FROM_REG(data->temp_max[nr]));
+ int val = 0;
+
+ if (nr < ARRAY_SIZE(data->temp_max))
+ val = TEMP_FROM_REG(data->temp_max[nr]);
+ return sprintf(buf, "%d\n", val);
}
static ssize_t temp_max_store(struct device *dev,
struct device_attribute *attr, const char *buf,
size_t count)
{
- int nr = to_sensor_dev_attr(attr)->index;
+ unsigned int nr = to_sensor_dev_attr(attr)->index;
struct lm85_data *data = dev_get_drvdata(dev);
struct i2c_client *client = data->client;
long val;
int err;
+ if (nr >= ARRAY_SIZE(data->temp_max))
+ return -EINVAL;
+
err = kstrtol(buf, 10, &val);
if (err)
return err;
@@ -1021,21 +1083,28 @@ static ssize_t pwm_auto_channels_show(struct device *dev,
struct device_attribute *attr,
char *buf)
{
- int nr = to_sensor_dev_attr(attr)->index;
+ unsigned int nr = to_sensor_dev_attr(attr)->index;
struct lm85_data *data = lm85_update_device(dev);
- return sprintf(buf, "%d\n", ZONE_FROM_REG(data->autofan[nr].config));
+ int val = 0;
+
+ if (nr < ARRAY_SIZE(data->autofan))
+ val = ZONE_FROM_REG(data->autofan[nr].config);
+ return sprintf(buf, "%d\n", val);
}
static ssize_t pwm_auto_channels_store(struct device *dev,
struct device_attribute *attr,
const char *buf, size_t count)
{
- int nr = to_sensor_dev_attr(attr)->index;
+ unsigned int nr = to_sensor_dev_attr(attr)->index;
struct lm85_data *data = dev_get_drvdata(dev);
struct i2c_client *client = data->client;
long val;
int err;
+ if (nr >= ARRAY_SIZE(data->autofan))
+ return -EINVAL;
+
err = kstrtol(buf, 10, &val);
if (err)
return err;
@@ -1052,21 +1121,28 @@ static ssize_t pwm_auto_channels_store(struct device *dev,
static ssize_t pwm_auto_pwm_min_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
- int nr = to_sensor_dev_attr(attr)->index;
+ unsigned int nr = to_sensor_dev_attr(attr)->index;
struct lm85_data *data = lm85_update_device(dev);
- return sprintf(buf, "%d\n", PWM_FROM_REG(data->autofan[nr].min_pwm));
+ int val = 0;
+
+ if (nr < ARRAY_SIZE(data->autofan))
+ val = PWM_FROM_REG(data->autofan[nr].min_pwm);
+ return sprintf(buf, "%d\n", val);
}
static ssize_t pwm_auto_pwm_min_store(struct device *dev,
struct device_attribute *attr,
const char *buf, size_t count)
{
- int nr = to_sensor_dev_attr(attr)->index;
+ unsigned int nr = to_sensor_dev_attr(attr)->index;
struct lm85_data *data = dev_get_drvdata(dev);
struct i2c_client *client = data->client;
unsigned long val;
int err;
+ if (nr >= ARRAY_SIZE(data->autofan))
+ return -EINVAL;
+
err = kstrtoul(buf, 10, &val);
if (err)
return err;
@@ -1083,22 +1159,29 @@ static ssize_t pwm_auto_pwm_minctl_show(struct device *dev,
struct device_attribute *attr,
char *buf)
{
- int nr = to_sensor_dev_attr(attr)->index;
+ unsigned int nr = to_sensor_dev_attr(attr)->index;
struct lm85_data *data = lm85_update_device(dev);
- return sprintf(buf, "%d\n", data->autofan[nr].min_off);
+ int val = 0;
+
+ if (nr < ARRAY_SIZE(data->autofan))
+ val = data->autofan[nr].min_off;
+ return sprintf(buf, "%d\n", val);
}
static ssize_t pwm_auto_pwm_minctl_store(struct device *dev,
struct device_attribute *attr,
const char *buf, size_t count)
{
- int nr = to_sensor_dev_attr(attr)->index;
+ unsigned int nr = to_sensor_dev_attr(attr)->index;
struct lm85_data *data = dev_get_drvdata(dev);
struct i2c_client *client = data->client;
u8 tmp;
long val;
int err;
+ if (nr >= ARRAY_SIZE(data->autofan))
+ return -EINVAL;
+
err = kstrtol(buf, 10, &val);
if (err)
return err;
@@ -1130,23 +1213,30 @@ static ssize_t temp_auto_temp_off_show(struct device *dev,
struct device_attribute *attr,
char *buf)
{
- int nr = to_sensor_dev_attr(attr)->index;
+ unsigned int nr = to_sensor_dev_attr(attr)->index;
struct lm85_data *data = lm85_update_device(dev);
- return sprintf(buf, "%d\n", TEMP_FROM_REG(data->zone[nr].limit) -
- HYST_FROM_REG(data->zone[nr].hyst));
+ int val = 0;
+
+ if (nr < ARRAY_SIZE(data->zone))
+ val = TEMP_FROM_REG(data->zone[nr].limit) -
+ HYST_FROM_REG(data->zone[nr].hyst);
+ return sprintf(buf, "%d\n", val);
}
static ssize_t temp_auto_temp_off_store(struct device *dev,
struct device_attribute *attr,
const char *buf, size_t count)
{
- int nr = to_sensor_dev_attr(attr)->index;
+ unsigned int nr = to_sensor_dev_attr(attr)->index;
struct lm85_data *data = dev_get_drvdata(dev);
struct i2c_client *client = data->client;
int min;
long val;
int err;
+ if (nr >= ARRAY_SIZE(data->zone))
+ return -EINVAL;
+
err = kstrtol(buf, 10, &val);
if (err)
return err;
@@ -1170,21 +1260,28 @@ static ssize_t temp_auto_temp_min_show(struct device *dev,
struct device_attribute *attr,
char *buf)
{
- int nr = to_sensor_dev_attr(attr)->index;
+ unsigned int nr = to_sensor_dev_attr(attr)->index;
struct lm85_data *data = lm85_update_device(dev);
- return sprintf(buf, "%d\n", TEMP_FROM_REG(data->zone[nr].limit));
+ int val = 0;
+
+ if (nr < ARRAY_SIZE(data->zone))
+ val = TEMP_FROM_REG(data->zone[nr].limit);
+ return sprintf(buf, "%d\n", val);
}
static ssize_t temp_auto_temp_min_store(struct device *dev,
struct device_attribute *attr,
const char *buf, size_t count)
{
- int nr = to_sensor_dev_attr(attr)->index;
+ unsigned int nr = to_sensor_dev_attr(attr)->index;
struct lm85_data *data = dev_get_drvdata(dev);
struct i2c_client *client = data->client;
long val;
int err;
+ if (nr >= ARRAY_SIZE(data->zone))
+ return -EINVAL;
+
err = kstrtol(buf, 10, &val);
if (err)
return err;
@@ -1194,7 +1291,7 @@ static ssize_t temp_auto_temp_min_store(struct device *dev,
lm85_write_value(client, LM85_REG_AFAN_LIMIT(nr),
data->zone[nr].limit);
-/* Update temp_auto_max and temp_auto_range */
+ /* Update temp_auto_max and temp_auto_range */
data->zone[nr].range = RANGE_TO_REG(
TEMP_FROM_REG(data->zone[nr].max_desired) -
TEMP_FROM_REG(data->zone[nr].limit));
@@ -1210,23 +1307,30 @@ static ssize_t temp_auto_temp_max_show(struct device *dev,
struct device_attribute *attr,
char *buf)
{
- int nr = to_sensor_dev_attr(attr)->index;
+ unsigned int nr = to_sensor_dev_attr(attr)->index;
struct lm85_data *data = lm85_update_device(dev);
- return sprintf(buf, "%d\n", TEMP_FROM_REG(data->zone[nr].limit) +
- RANGE_FROM_REG(data->zone[nr].range));
+ int val = 0;
+
+ if (nr < ARRAY_SIZE(data->zone))
+ val = TEMP_FROM_REG(data->zone[nr].limit) +
+ RANGE_FROM_REG(data->zone[nr].range);
+ return sprintf(buf, "%d\n", val);
}
static ssize_t temp_auto_temp_max_store(struct device *dev,
struct device_attribute *attr,
const char *buf, size_t count)
{
- int nr = to_sensor_dev_attr(attr)->index;
+ unsigned int nr = to_sensor_dev_attr(attr)->index;
struct lm85_data *data = dev_get_drvdata(dev);
struct i2c_client *client = data->client;
int min;
long val;
int err;
+ if (nr >= ARRAY_SIZE(data->zone))
+ return -EINVAL;
+
err = kstrtol(buf, 10, &val);
if (err)
return err;
@@ -1247,21 +1351,28 @@ static ssize_t temp_auto_temp_crit_show(struct device *dev,
struct device_attribute *attr,
char *buf)
{
- int nr = to_sensor_dev_attr(attr)->index;
+ unsigned int nr = to_sensor_dev_attr(attr)->index;
struct lm85_data *data = lm85_update_device(dev);
- return sprintf(buf, "%d\n", TEMP_FROM_REG(data->zone[nr].critical));
+ int val = 0;
+
+ if (nr < ARRAY_SIZE(data->zone))
+ val = TEMP_FROM_REG(data->zone[nr].critical);
+ return sprintf(buf, "%d\n", val);
}
static ssize_t temp_auto_temp_crit_store(struct device *dev,
struct device_attribute *attr,
const char *buf, size_t count)
{
- int nr = to_sensor_dev_attr(attr)->index;
+ unsigned int nr = to_sensor_dev_attr(attr)->index;
struct lm85_data *data = dev_get_drvdata(dev);
struct i2c_client *client = data->client;
long val;
int err;
+ if (nr >= ARRAY_SIZE(data->zone))
+ return -EINVAL;
+
err = kstrtol(buf, 10, &val);
if (err)
return err;
diff --git a/include/linux/hwmon-sysfs.h b/include/linux/hwmon-sysfs.h
index d896713359cd..f0505d10bfad 100644
--- a/include/linux/hwmon-sysfs.h
+++ b/include/linux/hwmon-sysfs.h
@@ -10,7 +10,7 @@
#include <linux/device.h>
#include <linux/kstrtox.h>
-struct sensor_device_attribute{
+struct sensor_device_attribute {
struct device_attribute dev_attr;
int index;
};
--
2.34.1
^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: [PATCH] lm85: Bounds check to_sensor_dev_attr()->index usage
2023-01-27 22:37 [PATCH] lm85: Bounds check to_sensor_dev_attr()->index usage Kees Cook
@ 2023-01-28 13:13 ` Guenter Roeck
2023-02-03 22:35 ` Kees Cook
0 siblings, 1 reply; 6+ messages in thread
From: Guenter Roeck @ 2023-01-28 13:13 UTC (permalink / raw)
To: Kees Cook; +Cc: Jean Delvare, linux-hwmon, linux-kernel, linux-hardening
On Fri, Jan 27, 2023 at 02:37:45PM -0800, Kees Cook wrote:
> The index into various register arrays was not bounds checked. Add
> checking. Seen under GCC 13:
>
> drivers/hwmon/lm85.c: In function 'pwm_auto_pwm_minctl_store':
> drivers/hwmon/lm85.c:1110:26: warning: array subscript [0, 31] is outside array bounds of 'struct lm85_autofan[3]' [-Warray-bounds=]
> 1110 | if (data->autofan[nr].min_off)
> | ~~~~~~~~~~~~~^~~~
> drivers/hwmon/lm85.c:317:29: note: while referencing 'autofan'
> 317 | struct lm85_autofan autofan[3];
> | ^~~~~~~
>
This is a false positive. The value can never be >= 3.
It is derived from the last value of the following
SENSOR_DEVICE_ATTR_RW() entries.
I resist making changes like this to the code just because
the compiler can not determine the range of a variable.
It blows up code size amd makes it hard to read just to
make the compiler happy.
Guenter
> Cc: Jean Delvare <jdelvare@suse.com>
> Cc: Guenter Roeck <linux@roeck-us.net>
> Cc: linux-hwmon@vger.kernel.org
> Signed-off-by: Kees Cook <keescook@chromium.org>
> ---
> drivers/hwmon/lm85.c | 221 +++++++++++++++++++++++++++---------
> include/linux/hwmon-sysfs.h | 2 +-
> 2 files changed, 167 insertions(+), 56 deletions(-)
>
> diff --git a/drivers/hwmon/lm85.c b/drivers/hwmon/lm85.c
> index 8d33c2484755..367a77660dda 100644
> --- a/drivers/hwmon/lm85.c
> +++ b/drivers/hwmon/lm85.c
> @@ -552,29 +552,40 @@ static struct lm85_data *lm85_update_device(struct device *dev)
> static ssize_t fan_show(struct device *dev, struct device_attribute *attr,
> char *buf)
> {
> - int nr = to_sensor_dev_attr(attr)->index;
> + unsigned int nr = to_sensor_dev_attr(attr)->index;
> struct lm85_data *data = lm85_update_device(dev);
> - return sprintf(buf, "%d\n", FAN_FROM_REG(data->fan[nr]));
> + int val = 0;
> +
> + if (nr < ARRAY_SIZE(data->fan))
> + val = FAN_FROM_REG(data->fan[nr]);
> + return sprintf(buf, "%d\n", val);
> }
>
> static ssize_t fan_min_show(struct device *dev, struct device_attribute *attr,
> char *buf)
> {
> - int nr = to_sensor_dev_attr(attr)->index;
> + unsigned int nr = to_sensor_dev_attr(attr)->index;
> struct lm85_data *data = lm85_update_device(dev);
> - return sprintf(buf, "%d\n", FAN_FROM_REG(data->fan_min[nr]));
> + int val = 0;
> +
> + if (nr < ARRAY_SIZE(data->fan_min))
> + val = FAN_FROM_REG(data->fan_min[nr]);
> + return sprintf(buf, "%d\n", val);
> }
>
> static ssize_t fan_min_store(struct device *dev,
> struct device_attribute *attr, const char *buf,
> size_t count)
> {
> - int nr = to_sensor_dev_attr(attr)->index;
> + unsigned int nr = to_sensor_dev_attr(attr)->index;
> struct lm85_data *data = dev_get_drvdata(dev);
> struct i2c_client *client = data->client;
> unsigned long val;
> int err;
>
> + if (nr >= ARRAY_SIZE(data->fan_min))
> + return -EINVAL;
> +
> err = kstrtoul(buf, 10, &val);
> if (err)
> return err;
> @@ -683,20 +694,27 @@ static SENSOR_DEVICE_ATTR_RO(fan4_alarm, alarm, 13);
> static ssize_t pwm_show(struct device *dev, struct device_attribute *attr,
> char *buf)
> {
> - int nr = to_sensor_dev_attr(attr)->index;
> + unsigned int nr = to_sensor_dev_attr(attr)->index;
> struct lm85_data *data = lm85_update_device(dev);
> - return sprintf(buf, "%d\n", PWM_FROM_REG(data->pwm[nr]));
> + int val = 0;
> +
> + if (nr < ARRAY_SIZE(data->pwm))
> + val = PWM_FROM_REG(data->pwm[nr]);
> + return sprintf(buf, "%d\n", val);
> }
>
> static ssize_t pwm_store(struct device *dev, struct device_attribute *attr,
> const char *buf, size_t count)
> {
> - int nr = to_sensor_dev_attr(attr)->index;
> + unsigned int nr = to_sensor_dev_attr(attr)->index;
> struct lm85_data *data = dev_get_drvdata(dev);
> struct i2c_client *client = data->client;
> unsigned long val;
> int err;
>
> + if (nr >= ARRAY_SIZE(data->pwm))
> + return -EINVAL;
> +
> err = kstrtoul(buf, 10, &val);
> if (err)
> return err;
> @@ -711,11 +729,12 @@ static ssize_t pwm_store(struct device *dev, struct device_attribute *attr,
> static ssize_t pwm_enable_show(struct device *dev,
> struct device_attribute *attr, char *buf)
> {
> - int nr = to_sensor_dev_attr(attr)->index;
> + unsigned int nr = to_sensor_dev_attr(attr)->index;
> struct lm85_data *data = lm85_update_device(dev);
> - int pwm_zone, enable;
> + int pwm_zone = -1, enable;
>
> - pwm_zone = ZONE_FROM_REG(data->autofan[nr].config);
> + if (nr < ARRAY_SIZE(data->autofan))
> + pwm_zone = ZONE_FROM_REG(data->autofan[nr].config);
> switch (pwm_zone) {
> case -1: /* PWM is always at 100% */
> enable = 0;
> @@ -734,13 +753,16 @@ static ssize_t pwm_enable_store(struct device *dev,
> struct device_attribute *attr,
> const char *buf, size_t count)
> {
> - int nr = to_sensor_dev_attr(attr)->index;
> + unsigned int nr = to_sensor_dev_attr(attr)->index;
> struct lm85_data *data = dev_get_drvdata(dev);
> struct i2c_client *client = data->client;
> u8 config;
> unsigned long val;
> int err;
>
> + if (nr >= ARRAY_SIZE(data->autofan))
> + return -EINVAL;
> +
> err = kstrtoul(buf, 10, &val);
> if (err)
> return err;
> @@ -777,10 +799,13 @@ static ssize_t pwm_enable_store(struct device *dev,
> static ssize_t pwm_freq_show(struct device *dev,
> struct device_attribute *attr, char *buf)
> {
> - int nr = to_sensor_dev_attr(attr)->index;
> + unsigned int nr = to_sensor_dev_attr(attr)->index;
> struct lm85_data *data = lm85_update_device(dev);
> int freq;
>
> + if (nr >= ARRAY_SIZE(data->pwm_freq))
> + return -EINVAL;
> +
> if (IS_ADT7468_HFPWM(data))
> freq = 22500;
> else
> @@ -794,12 +819,15 @@ static ssize_t pwm_freq_store(struct device *dev,
> struct device_attribute *attr, const char *buf,
> size_t count)
> {
> - int nr = to_sensor_dev_attr(attr)->index;
> + unsigned int nr = to_sensor_dev_attr(attr)->index;
> struct lm85_data *data = dev_get_drvdata(dev);
> struct i2c_client *client = data->client;
> unsigned long val;
> int err;
>
> + if (nr >= ARRAY_SIZE(data->pwm_freq))
> + return -EINVAL;
> +
> err = kstrtoul(buf, 10, &val);
> if (err)
> return err;
> @@ -843,10 +871,13 @@ static SENSOR_DEVICE_ATTR_RW(pwm3_freq, pwm_freq, 2);
> static ssize_t in_show(struct device *dev, struct device_attribute *attr,
> char *buf)
> {
> - int nr = to_sensor_dev_attr(attr)->index;
> + unsigned int nr = to_sensor_dev_attr(attr)->index;
> struct lm85_data *data = lm85_update_device(dev);
> - return sprintf(buf, "%d\n", INSEXT_FROM_REG(nr, data->in[nr],
> - data->in_ext[nr]));
> + int val = 0;
> +
> + if (nr < ARRAY_SIZE(data->in))
> + val = INSEXT_FROM_REG(nr, data->in[nr], data->in_ext[nr]);
> + return sprintf(buf, "%d\n", val);
> }
>
> static ssize_t in_min_show(struct device *dev, struct device_attribute *attr,
> @@ -854,18 +885,25 @@ static ssize_t in_min_show(struct device *dev, struct device_attribute *attr,
> {
> int nr = to_sensor_dev_attr(attr)->index;
> struct lm85_data *data = lm85_update_device(dev);
> - return sprintf(buf, "%d\n", INS_FROM_REG(nr, data->in_min[nr]));
> + int val = 0;
> +
> + if (nr < ARRAY_SIZE(data->in_min))
> + val = INS_FROM_REG(nr, data->in_min[nr]);
> + return sprintf(buf, "%d\n", val);
> }
>
> static ssize_t in_min_store(struct device *dev, struct device_attribute *attr,
> const char *buf, size_t count)
> {
> - int nr = to_sensor_dev_attr(attr)->index;
> + unsigned int nr = to_sensor_dev_attr(attr)->index;
> struct lm85_data *data = dev_get_drvdata(dev);
> struct i2c_client *client = data->client;
> long val;
> int err;
>
> + if (nr >= ARRAY_SIZE(data->in_min))
> + return -EINVAL;
> +
> err = kstrtol(buf, 10, &val);
> if (err)
> return err;
> @@ -880,20 +918,27 @@ static ssize_t in_min_store(struct device *dev, struct device_attribute *attr,
> static ssize_t in_max_show(struct device *dev, struct device_attribute *attr,
> char *buf)
> {
> - int nr = to_sensor_dev_attr(attr)->index;
> + unsigned int nr = to_sensor_dev_attr(attr)->index;
> struct lm85_data *data = lm85_update_device(dev);
> - return sprintf(buf, "%d\n", INS_FROM_REG(nr, data->in_max[nr]));
> + int val = 0;
> +
> + if (nr < ARRAY_SIZE(data->in_max))
> + val = INS_FROM_REG(nr, data->in_max[nr]);
> + return sprintf(buf, "%d\n", val);
> }
>
> static ssize_t in_max_store(struct device *dev, struct device_attribute *attr,
> const char *buf, size_t count)
> {
> - int nr = to_sensor_dev_attr(attr)->index;
> + unsigned int nr = to_sensor_dev_attr(attr)->index;
> struct lm85_data *data = dev_get_drvdata(dev);
> struct i2c_client *client = data->client;
> long val;
> int err;
>
> + if (nr >= ARRAY_SIZE(data->in_max))
> + return -EINVAL;
> +
> err = kstrtol(buf, 10, &val);
> if (err)
> return err;
> @@ -935,30 +980,40 @@ static SENSOR_DEVICE_ATTR_RW(in7_max, in_max, 7);
> static ssize_t temp_show(struct device *dev, struct device_attribute *attr,
> char *buf)
> {
> - int nr = to_sensor_dev_attr(attr)->index;
> + unsigned int nr = to_sensor_dev_attr(attr)->index;
> struct lm85_data *data = lm85_update_device(dev);
> - return sprintf(buf, "%d\n", TEMPEXT_FROM_REG(data->temp[nr],
> - data->temp_ext[nr]));
> + int val = 0;
> +
> + if (nr < ARRAY_SIZE(data->temp))
> + val = TEMPEXT_FROM_REG(data->temp[nr], data->temp_ext[nr]);
> + return sprintf(buf, "%d\n", val);
> }
>
> static ssize_t temp_min_show(struct device *dev,
> struct device_attribute *attr, char *buf)
> {
> - int nr = to_sensor_dev_attr(attr)->index;
> + unsigned int nr = to_sensor_dev_attr(attr)->index;
> struct lm85_data *data = lm85_update_device(dev);
> - return sprintf(buf, "%d\n", TEMP_FROM_REG(data->temp_min[nr]));
> + int val = 0;
> +
> + if (nr < ARRAY_SIZE(data->temp_min))
> + val = TEMP_FROM_REG(data->temp_min[nr]);
> + return sprintf(buf, "%d\n", val);
> }
>
> static ssize_t temp_min_store(struct device *dev,
> struct device_attribute *attr, const char *buf,
> size_t count)
> {
> - int nr = to_sensor_dev_attr(attr)->index;
> + unsigned int nr = to_sensor_dev_attr(attr)->index;
> struct lm85_data *data = dev_get_drvdata(dev);
> struct i2c_client *client = data->client;
> long val;
> int err;
>
> + if (nr >= ARRAY_SIZE(data->temp_min))
> + return -EINVAL;
> +
> err = kstrtol(buf, 10, &val);
> if (err)
> return err;
> @@ -976,21 +1031,28 @@ static ssize_t temp_min_store(struct device *dev,
> static ssize_t temp_max_show(struct device *dev,
> struct device_attribute *attr, char *buf)
> {
> - int nr = to_sensor_dev_attr(attr)->index;
> + unsigned int nr = to_sensor_dev_attr(attr)->index;
> struct lm85_data *data = lm85_update_device(dev);
> - return sprintf(buf, "%d\n", TEMP_FROM_REG(data->temp_max[nr]));
> + int val = 0;
> +
> + if (nr < ARRAY_SIZE(data->temp_max))
> + val = TEMP_FROM_REG(data->temp_max[nr]);
> + return sprintf(buf, "%d\n", val);
> }
>
> static ssize_t temp_max_store(struct device *dev,
> struct device_attribute *attr, const char *buf,
> size_t count)
> {
> - int nr = to_sensor_dev_attr(attr)->index;
> + unsigned int nr = to_sensor_dev_attr(attr)->index;
> struct lm85_data *data = dev_get_drvdata(dev);
> struct i2c_client *client = data->client;
> long val;
> int err;
>
> + if (nr >= ARRAY_SIZE(data->temp_max))
> + return -EINVAL;
> +
> err = kstrtol(buf, 10, &val);
> if (err)
> return err;
> @@ -1021,21 +1083,28 @@ static ssize_t pwm_auto_channels_show(struct device *dev,
> struct device_attribute *attr,
> char *buf)
> {
> - int nr = to_sensor_dev_attr(attr)->index;
> + unsigned int nr = to_sensor_dev_attr(attr)->index;
> struct lm85_data *data = lm85_update_device(dev);
> - return sprintf(buf, "%d\n", ZONE_FROM_REG(data->autofan[nr].config));
> + int val = 0;
> +
> + if (nr < ARRAY_SIZE(data->autofan))
> + val = ZONE_FROM_REG(data->autofan[nr].config);
> + return sprintf(buf, "%d\n", val);
> }
>
> static ssize_t pwm_auto_channels_store(struct device *dev,
> struct device_attribute *attr,
> const char *buf, size_t count)
> {
> - int nr = to_sensor_dev_attr(attr)->index;
> + unsigned int nr = to_sensor_dev_attr(attr)->index;
> struct lm85_data *data = dev_get_drvdata(dev);
> struct i2c_client *client = data->client;
> long val;
> int err;
>
> + if (nr >= ARRAY_SIZE(data->autofan))
> + return -EINVAL;
> +
> err = kstrtol(buf, 10, &val);
> if (err)
> return err;
> @@ -1052,21 +1121,28 @@ static ssize_t pwm_auto_channels_store(struct device *dev,
> static ssize_t pwm_auto_pwm_min_show(struct device *dev,
> struct device_attribute *attr, char *buf)
> {
> - int nr = to_sensor_dev_attr(attr)->index;
> + unsigned int nr = to_sensor_dev_attr(attr)->index;
> struct lm85_data *data = lm85_update_device(dev);
> - return sprintf(buf, "%d\n", PWM_FROM_REG(data->autofan[nr].min_pwm));
> + int val = 0;
> +
> + if (nr < ARRAY_SIZE(data->autofan))
> + val = PWM_FROM_REG(data->autofan[nr].min_pwm);
> + return sprintf(buf, "%d\n", val);
> }
>
> static ssize_t pwm_auto_pwm_min_store(struct device *dev,
> struct device_attribute *attr,
> const char *buf, size_t count)
> {
> - int nr = to_sensor_dev_attr(attr)->index;
> + unsigned int nr = to_sensor_dev_attr(attr)->index;
> struct lm85_data *data = dev_get_drvdata(dev);
> struct i2c_client *client = data->client;
> unsigned long val;
> int err;
>
> + if (nr >= ARRAY_SIZE(data->autofan))
> + return -EINVAL;
> +
> err = kstrtoul(buf, 10, &val);
> if (err)
> return err;
> @@ -1083,22 +1159,29 @@ static ssize_t pwm_auto_pwm_minctl_show(struct device *dev,
> struct device_attribute *attr,
> char *buf)
> {
> - int nr = to_sensor_dev_attr(attr)->index;
> + unsigned int nr = to_sensor_dev_attr(attr)->index;
> struct lm85_data *data = lm85_update_device(dev);
> - return sprintf(buf, "%d\n", data->autofan[nr].min_off);
> + int val = 0;
> +
> + if (nr < ARRAY_SIZE(data->autofan))
> + val = data->autofan[nr].min_off;
> + return sprintf(buf, "%d\n", val);
> }
>
> static ssize_t pwm_auto_pwm_minctl_store(struct device *dev,
> struct device_attribute *attr,
> const char *buf, size_t count)
> {
> - int nr = to_sensor_dev_attr(attr)->index;
> + unsigned int nr = to_sensor_dev_attr(attr)->index;
> struct lm85_data *data = dev_get_drvdata(dev);
> struct i2c_client *client = data->client;
> u8 tmp;
> long val;
> int err;
>
> + if (nr >= ARRAY_SIZE(data->autofan))
> + return -EINVAL;
> +
> err = kstrtol(buf, 10, &val);
> if (err)
> return err;
> @@ -1130,23 +1213,30 @@ static ssize_t temp_auto_temp_off_show(struct device *dev,
> struct device_attribute *attr,
> char *buf)
> {
> - int nr = to_sensor_dev_attr(attr)->index;
> + unsigned int nr = to_sensor_dev_attr(attr)->index;
> struct lm85_data *data = lm85_update_device(dev);
> - return sprintf(buf, "%d\n", TEMP_FROM_REG(data->zone[nr].limit) -
> - HYST_FROM_REG(data->zone[nr].hyst));
> + int val = 0;
> +
> + if (nr < ARRAY_SIZE(data->zone))
> + val = TEMP_FROM_REG(data->zone[nr].limit) -
> + HYST_FROM_REG(data->zone[nr].hyst);
> + return sprintf(buf, "%d\n", val);
> }
>
> static ssize_t temp_auto_temp_off_store(struct device *dev,
> struct device_attribute *attr,
> const char *buf, size_t count)
> {
> - int nr = to_sensor_dev_attr(attr)->index;
> + unsigned int nr = to_sensor_dev_attr(attr)->index;
> struct lm85_data *data = dev_get_drvdata(dev);
> struct i2c_client *client = data->client;
> int min;
> long val;
> int err;
>
> + if (nr >= ARRAY_SIZE(data->zone))
> + return -EINVAL;
> +
> err = kstrtol(buf, 10, &val);
> if (err)
> return err;
> @@ -1170,21 +1260,28 @@ static ssize_t temp_auto_temp_min_show(struct device *dev,
> struct device_attribute *attr,
> char *buf)
> {
> - int nr = to_sensor_dev_attr(attr)->index;
> + unsigned int nr = to_sensor_dev_attr(attr)->index;
> struct lm85_data *data = lm85_update_device(dev);
> - return sprintf(buf, "%d\n", TEMP_FROM_REG(data->zone[nr].limit));
> + int val = 0;
> +
> + if (nr < ARRAY_SIZE(data->zone))
> + val = TEMP_FROM_REG(data->zone[nr].limit);
> + return sprintf(buf, "%d\n", val);
> }
>
> static ssize_t temp_auto_temp_min_store(struct device *dev,
> struct device_attribute *attr,
> const char *buf, size_t count)
> {
> - int nr = to_sensor_dev_attr(attr)->index;
> + unsigned int nr = to_sensor_dev_attr(attr)->index;
> struct lm85_data *data = dev_get_drvdata(dev);
> struct i2c_client *client = data->client;
> long val;
> int err;
>
> + if (nr >= ARRAY_SIZE(data->zone))
> + return -EINVAL;
> +
> err = kstrtol(buf, 10, &val);
> if (err)
> return err;
> @@ -1194,7 +1291,7 @@ static ssize_t temp_auto_temp_min_store(struct device *dev,
> lm85_write_value(client, LM85_REG_AFAN_LIMIT(nr),
> data->zone[nr].limit);
>
> -/* Update temp_auto_max and temp_auto_range */
> + /* Update temp_auto_max and temp_auto_range */
> data->zone[nr].range = RANGE_TO_REG(
> TEMP_FROM_REG(data->zone[nr].max_desired) -
> TEMP_FROM_REG(data->zone[nr].limit));
> @@ -1210,23 +1307,30 @@ static ssize_t temp_auto_temp_max_show(struct device *dev,
> struct device_attribute *attr,
> char *buf)
> {
> - int nr = to_sensor_dev_attr(attr)->index;
> + unsigned int nr = to_sensor_dev_attr(attr)->index;
> struct lm85_data *data = lm85_update_device(dev);
> - return sprintf(buf, "%d\n", TEMP_FROM_REG(data->zone[nr].limit) +
> - RANGE_FROM_REG(data->zone[nr].range));
> + int val = 0;
> +
> + if (nr < ARRAY_SIZE(data->zone))
> + val = TEMP_FROM_REG(data->zone[nr].limit) +
> + RANGE_FROM_REG(data->zone[nr].range);
> + return sprintf(buf, "%d\n", val);
> }
>
> static ssize_t temp_auto_temp_max_store(struct device *dev,
> struct device_attribute *attr,
> const char *buf, size_t count)
> {
> - int nr = to_sensor_dev_attr(attr)->index;
> + unsigned int nr = to_sensor_dev_attr(attr)->index;
> struct lm85_data *data = dev_get_drvdata(dev);
> struct i2c_client *client = data->client;
> int min;
> long val;
> int err;
>
> + if (nr >= ARRAY_SIZE(data->zone))
> + return -EINVAL;
> +
> err = kstrtol(buf, 10, &val);
> if (err)
> return err;
> @@ -1247,21 +1351,28 @@ static ssize_t temp_auto_temp_crit_show(struct device *dev,
> struct device_attribute *attr,
> char *buf)
> {
> - int nr = to_sensor_dev_attr(attr)->index;
> + unsigned int nr = to_sensor_dev_attr(attr)->index;
> struct lm85_data *data = lm85_update_device(dev);
> - return sprintf(buf, "%d\n", TEMP_FROM_REG(data->zone[nr].critical));
> + int val = 0;
> +
> + if (nr < ARRAY_SIZE(data->zone))
> + val = TEMP_FROM_REG(data->zone[nr].critical);
> + return sprintf(buf, "%d\n", val);
> }
>
> static ssize_t temp_auto_temp_crit_store(struct device *dev,
> struct device_attribute *attr,
> const char *buf, size_t count)
> {
> - int nr = to_sensor_dev_attr(attr)->index;
> + unsigned int nr = to_sensor_dev_attr(attr)->index;
> struct lm85_data *data = dev_get_drvdata(dev);
> struct i2c_client *client = data->client;
> long val;
> int err;
>
> + if (nr >= ARRAY_SIZE(data->zone))
> + return -EINVAL;
> +
> err = kstrtol(buf, 10, &val);
> if (err)
> return err;
> diff --git a/include/linux/hwmon-sysfs.h b/include/linux/hwmon-sysfs.h
> index d896713359cd..f0505d10bfad 100644
> --- a/include/linux/hwmon-sysfs.h
> +++ b/include/linux/hwmon-sysfs.h
> @@ -10,7 +10,7 @@
> #include <linux/device.h>
> #include <linux/kstrtox.h>
>
> -struct sensor_device_attribute{
> +struct sensor_device_attribute {
> struct device_attribute dev_attr;
> int index;
> };
> --
> 2.34.1
>
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] lm85: Bounds check to_sensor_dev_attr()->index usage
2023-01-28 13:13 ` Guenter Roeck
@ 2023-02-03 22:35 ` Kees Cook
2023-02-04 1:57 ` Guenter Roeck
0 siblings, 1 reply; 6+ messages in thread
From: Kees Cook @ 2023-02-03 22:35 UTC (permalink / raw)
To: Guenter Roeck; +Cc: Jean Delvare, linux-hwmon, linux-kernel, linux-hardening
On Sat, Jan 28, 2023 at 05:13:19AM -0800, Guenter Roeck wrote:
> On Fri, Jan 27, 2023 at 02:37:45PM -0800, Kees Cook wrote:
> > The index into various register arrays was not bounds checked. Add
> > checking. Seen under GCC 13:
> >
> > drivers/hwmon/lm85.c: In function 'pwm_auto_pwm_minctl_store':
> > drivers/hwmon/lm85.c:1110:26: warning: array subscript [0, 31] is outside array bounds of 'struct lm85_autofan[3]' [-Warray-bounds=]
> > 1110 | if (data->autofan[nr].min_off)
> > | ~~~~~~~~~~~~~^~~~
> > drivers/hwmon/lm85.c:317:29: note: while referencing 'autofan'
> > 317 | struct lm85_autofan autofan[3];
> > | ^~~~~~~
> >
>
> This is a false positive. The value can never be >= 3.
> It is derived from the last value of the following
> SENSOR_DEVICE_ATTR_RW() entries.
>
> I resist making changes like this to the code just because
> the compiler can not determine the range of a variable.
> It blows up code size amd makes it hard to read just to
> make the compiler happy.
I think it's worth it given the index is an "int" and it'd be very easy
for things to go wrong in the face of other memory corruption, etc. I've
sent a v2 that I think is much more readable and non-invasive but
provides similar robustness.
-Kees
--
Kees Cook
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] lm85: Bounds check to_sensor_dev_attr()->index usage
2023-02-03 22:35 ` Kees Cook
@ 2023-02-04 1:57 ` Guenter Roeck
2023-02-04 18:55 ` Kees Cook
0 siblings, 1 reply; 6+ messages in thread
From: Guenter Roeck @ 2023-02-04 1:57 UTC (permalink / raw)
To: Kees Cook; +Cc: Jean Delvare, linux-hwmon, linux-kernel, linux-hardening
On Fri, Feb 03, 2023 at 10:35:05PM +0000, Kees Cook wrote:
> On Sat, Jan 28, 2023 at 05:13:19AM -0800, Guenter Roeck wrote:
> > On Fri, Jan 27, 2023 at 02:37:45PM -0800, Kees Cook wrote:
> > > The index into various register arrays was not bounds checked. Add
> > > checking. Seen under GCC 13:
> > >
> > > drivers/hwmon/lm85.c: In function 'pwm_auto_pwm_minctl_store':
> > > drivers/hwmon/lm85.c:1110:26: warning: array subscript [0, 31] is outside array bounds of 'struct lm85_autofan[3]' [-Warray-bounds=]
> > > 1110 | if (data->autofan[nr].min_off)
> > > | ~~~~~~~~~~~~~^~~~
> > > drivers/hwmon/lm85.c:317:29: note: while referencing 'autofan'
> > > 317 | struct lm85_autofan autofan[3];
> > > | ^~~~~~~
> > >
> >
> > This is a false positive. The value can never be >= 3.
> > It is derived from the last value of the following
> > SENSOR_DEVICE_ATTR_RW() entries.
> >
> > I resist making changes like this to the code just because
> > the compiler can not determine the range of a variable.
> > It blows up code size amd makes it hard to read just to
> > make the compiler happy.
>
> I think it's worth it given the index is an "int" and it'd be very easy
> for things to go wrong in the face of other memory corruption, etc. I've
> sent a v2 that I think is much more readable and non-invasive but
> provides similar robustness.
>
That line of argument would suggest that we should perform parameter checks
on each function entry all over the place, no matter if the range is known
to be valid or not. Maybe that is the way things are going, but I don't
like it at all. I have seen that kind of code before, in the telco space,
where it typically at least doubled code size and resulted in mediocre
performance, just because of a rule that mandated checking all parameters
at the beginning of each function.
I assume this is just one of many many patches you plan to send to add
parameter checks to similar hwmon code ? I _really_ don't want to have
the hwmon code cluttered with such unnecessary checks.
Guenter
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] lm85: Bounds check to_sensor_dev_attr()->index usage
2023-02-04 1:57 ` Guenter Roeck
@ 2023-02-04 18:55 ` Kees Cook
2023-02-05 17:37 ` Guenter Roeck
0 siblings, 1 reply; 6+ messages in thread
From: Kees Cook @ 2023-02-04 18:55 UTC (permalink / raw)
To: Guenter Roeck; +Cc: Jean Delvare, linux-hwmon, linux-kernel, linux-hardening
On Fri, Feb 03, 2023 at 05:57:00PM -0800, Guenter Roeck wrote:
> That line of argument would suggest that we should perform parameter checks
> on each function entry all over the place, no matter if the range is known
> to be valid or not. Maybe that is the way things are going, but I don't
> like it at all. I have seen that kind of code before, in the telco space,
> where it typically at least doubled code size and resulted in mediocre
> performance, just because of a rule that mandated checking all parameters
> at the beginning of each function.
Well, I doubt I'll be able to change your opinion of telco code, but I
do think robustness is not an unreasonable default state for software,
and that GCC and Clang do a pretty good job with optimization, etc.
> I assume this is just one of many many patches you plan to send to add
> parameter checks to similar hwmon code ? I _really_ don't want to have
> the hwmon code cluttered with such unnecessary checks.
I was trying to provide complete coverage inspired by the specific
complaint GCC had, but this would also silence the warning:
diff --git a/drivers/hwmon/lm85.c b/drivers/hwmon/lm85.c
index 8d33c2484755..87d2455e721f 100644
--- a/drivers/hwmon/lm85.c
+++ b/drivers/hwmon/lm85.c
@@ -1106,6 +1106,7 @@ static ssize_t pwm_auto_pwm_minctl_store(struct device *dev,
mutex_lock(&data->update_lock);
data->autofan[nr].min_off = val;
tmp = lm85_read_value(client, LM85_REG_AFAN_SPIKE1);
+ nr = clamp_t(int, nr, 0, ARRAY_SIZE(data->autofan) - 1);
tmp &= ~(0x20 << nr);
if (data->autofan[nr].min_off)
tmp |= 0x20 << nr;
What's happening is GCC see that "nr" is used as a shift argument, so it
believes (not unreasonably) that this otherwise unknown value could be
up to 32. Here we can give it the bounded range ahead of time, keeping
it happy.
--
Kees Cook
^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: [PATCH] lm85: Bounds check to_sensor_dev_attr()->index usage
2023-02-04 18:55 ` Kees Cook
@ 2023-02-05 17:37 ` Guenter Roeck
0 siblings, 0 replies; 6+ messages in thread
From: Guenter Roeck @ 2023-02-05 17:37 UTC (permalink / raw)
To: Kees Cook; +Cc: Jean Delvare, linux-hwmon, linux-kernel, linux-hardening
On 2/4/23 10:55, Kees Cook wrote:
> On Fri, Feb 03, 2023 at 05:57:00PM -0800, Guenter Roeck wrote:
>> That line of argument would suggest that we should perform parameter checks
>> on each function entry all over the place, no matter if the range is known
>> to be valid or not. Maybe that is the way things are going, but I don't
>> like it at all. I have seen that kind of code before, in the telco space,
>> where it typically at least doubled code size and resulted in mediocre
>> performance, just because of a rule that mandated checking all parameters
>> at the beginning of each function.
>
> Well, I doubt I'll be able to change your opinion of telco code, but I
> do think robustness is not an unreasonable default state for software,
> and that GCC and Clang do a pretty good job with optimization, etc.
>
>> I assume this is just one of many many patches you plan to send to add
>> parameter checks to similar hwmon code ? I _really_ don't want to have
>> the hwmon code cluttered with such unnecessary checks.
>
> I was trying to provide complete coverage inspired by the specific
> complaint GCC had, but this would also silence the warning:
>
> diff --git a/drivers/hwmon/lm85.c b/drivers/hwmon/lm85.c
> index 8d33c2484755..87d2455e721f 100644
> --- a/drivers/hwmon/lm85.c
> +++ b/drivers/hwmon/lm85.c
> @@ -1106,6 +1106,7 @@ static ssize_t pwm_auto_pwm_minctl_store(struct device *dev,
> mutex_lock(&data->update_lock);
> data->autofan[nr].min_off = val;
> tmp = lm85_read_value(client, LM85_REG_AFAN_SPIKE1);
> + nr = clamp_t(int, nr, 0, ARRAY_SIZE(data->autofan) - 1);
> tmp &= ~(0x20 << nr);
> if (data->autofan[nr].min_off)
> tmp |= 0x20 << nr;
>
> What's happening is GCC see that "nr" is used as a shift argument, so it
> believes (not unreasonably) that this otherwise unknown value could be
> up to 32. Here we can give it the bounded range ahead of time, keeping
> it happy.
>
I'll accept that if you also add a note clarifying that this is to silence
a gcc/clang warning.
Guenter
^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2023-02-05 17:37 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2023-01-27 22:37 [PATCH] lm85: Bounds check to_sensor_dev_attr()->index usage Kees Cook
2023-01-28 13:13 ` Guenter Roeck
2023-02-03 22:35 ` Kees Cook
2023-02-04 1:57 ` Guenter Roeck
2023-02-04 18:55 ` Kees Cook
2023-02-05 17:37 ` Guenter Roeck
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).