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hwmon: (w83793) Fix NULL pointer dereference by removing unnecessary structure field

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commit dd4d747ef05addab887dc8ff0d6ab9860bbcd783 upstream.

If driver read tmp value sufficient for
(tmp & 0x08) && (!(tmp & 0x80)) && ((tmp & 0x7) == ((tmp >> 4) & 0x7))
from device then Null pointer dereference occurs.
(It is possible if tmp = 0b0xyz1xyz, where same literals mean same numbers)
Also lm75[] does not serve a purpose anymore after switching to
devm_i2c_new_dummy_device() in w83791d_detect_subclients().

The patch fixes possible NULL pointer dereference by removing lm75[].

Found by Linux Driver Verification project (linuxtesting.org).

Cc: stable@vger.kernel.org
Signed-off-by: Nadezda Lutovinova <lutovinova@ispras.ru>
Link: https://lore.kernel.org/r/20210921155153.28098-3-lutovinova@ispras.ru
[groeck: Dropped unnecessary continuation lines, fixed multi-line alignments]
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Nadezda Lutovinova 2021-09-21 18:51:53 +03:00 committed by Greg Kroah-Hartman
parent 196dabd96b
commit 7c4fd5de39
1 changed files with 11 additions and 15 deletions
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22
drivers/hwmon/w83793.c
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@ -202,7 +202,6 @@ static inline s8 TEMP_TO_REG(long val, s8 min, s8 max)
}
struct w83793_data {
struct i2c_client *lm75[2];
struct device *hwmon_dev;
struct mutex update_lock;
char valid; /* !=0 if following fields are valid */
@ -1566,7 +1565,6 @@ w83793_detect_subclients(struct i2c_client *client)
int address = client->addr;
u8 tmp;
struct i2c_adapter *adapter = client->adapter;
struct w83793_data *data = i2c_get_clientdata(client);
id = i2c_adapter_id(adapter);
if (force_subclients[0] == id && force_subclients[1] == address) {
@ -1586,20 +1584,18 @@ w83793_detect_subclients(struct i2c_client *client)
}
tmp = w83793_read_value(client, W83793_REG_I2C_SUBADDR);
if (!(tmp & 0x08))
data->lm75[0] = devm_i2c_new_dummy_device(&client->dev, adapter,
0x48 + (tmp & 0x7));
if (!(tmp & 0x80)) {
if (!IS_ERR(data->lm75[0])
&& ((tmp & 0x7) == ((tmp >> 4) & 0x7))) {
if (!(tmp & 0x88) && (tmp & 0x7) == ((tmp >> 4) & 0x7)) {
dev_err(&client->dev,
"duplicate addresses 0x%x, "
"use force_subclients\n", data->lm75[0]->addr);
"duplicate addresses 0x%x, use force_subclient\n", 0x48 + (tmp & 0x7));
return -ENODEV;
}
data->lm75[1] = devm_i2c_new_dummy_device(&client->dev, adapter,
0x48 + ((tmp >> 4) & 0x7));
}
if (!(tmp & 0x08))
devm_i2c_new_dummy_device(&client->dev, adapter, 0x48 + (tmp & 0x7));
if (!(tmp & 0x80))
devm_i2c_new_dummy_device(&client->dev, adapter, 0x48 + ((tmp >> 4) & 0x7));
return 0;
}