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Commit 200ced5b authored by Nadezda Lutovinova's avatar Nadezda Lutovinova Committed by Greg Kroah-Hartman
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hwmon: (w83792d) Fix NULL pointer dereference by removing unnecessary structure field 



commit 0f36b88173f028e372668ae040ab1a496834d278 upstream.

If driver read val value sufficient for
(val & 0x08) && (!(val & 0x80)) && ((val & 0x7) == ((val >> 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/20210921155153.28098-2-lutovinova@ispras.ru


[groeck: Dropped unnecessary continuation lines, fixed multipline alignment]
Signed-off-by: default avatarGuenter Roeck <linux@roeck-us.net>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 6cb01fe6

drivers/hwmon/w83792d.c

+11 −17
Original line number Diff line number Diff line
@@ -264,9 +264,6 @@ struct w83792d_data { 
	char valid;		/* !=0 if following fields are valid */

	unsigned long last_updated;	/* In jiffies */



	/* array of 2 pointers to subclients */

	struct i2c_client *lm75[2];



	u8 in[9];		/* Register value */

	u8 in_max[9];		/* Register value */

	u8 in_min[9];		/* Register value */
@@ -928,7 +925,6 @@ w83792d_detect_subclients(struct i2c_client *new_client) 
	int address = new_client->addr;

	u8 val;

	struct i2c_adapter *adapter = new_client->adapter;

	struct w83792d_data *data = i2c_get_clientdata(new_client);



	id = i2c_adapter_id(adapter);

	if (force_subclients[0] == id && force_subclients[1] == address) {
@@ -947,20 +943,18 @@ w83792d_detect_subclients(struct i2c_client *new_client) 
	}



	val = w83792d_read_value(new_client, W83792D_REG_I2C_SUBADDR);

	if (!(val & 0x08))

		data->lm75[0] = devm_i2c_new_dummy_device(&new_client->dev, adapter,

							  0x48 + (val & 0x7));

	if (!(val & 0x80)) {

		if (!IS_ERR(data->lm75[0]) &&

			((val & 0x7) == ((val >> 4) & 0x7))) {



	if (!(val & 0x88) && (val & 0x7) == ((val >> 4) & 0x7)) {

		dev_err(&new_client->dev,

				"duplicate addresses 0x%x, use force_subclient\n",

				data->lm75[0]->addr);

			"duplicate addresses 0x%x, use force_subclient\n", 0x48 + (val & 0x7));

		return -ENODEV;

	}

		data->lm75[1] = devm_i2c_new_dummy_device(&new_client->dev, adapter,

							  0x48 + ((val >> 4) & 0x7));

	}



	if (!(val & 0x08))

		devm_i2c_new_dummy_device(&new_client->dev, adapter, 0x48 + (val & 0x7));



	if (!(val & 0x80))

		devm_i2c_new_dummy_device(&new_client->dev, adapter, 0x48 + ((val >> 4) & 0x7));



	return 0;

}