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Commit 6cb01fe6 authored by Nadezda Lutovinova's avatar Nadezda Lutovinova Committed by Greg Kroah-Hartman
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hwmon: (w83793) Fix NULL pointer dereference by removing unnecessary structure field 



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: default avatarNadezda 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: default avatarGuenter Roeck <linux@roeck-us.net>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 504cf969

drivers/hwmon/w83793.c

+11 −15
Original line number Diff line number Diff line
@@ -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;

}