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hwmon: (w83791d) Fix NULL pointer dereference by removing unnecessary structure field

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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: Nadezda Lutovinova <lutovinova@ispras.ru>
Link: https://lore.kernel.org/r/20210921155153.28098-1-lutovinova@ispras.ru
[groeck: Dropped unnecessary continuation lines, fixed multi-line alignment]
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
This commit is contained in:
Nadezda Lutovinova 2021-09-21 18:51:51 +03:00 committed by Guenter Roeck
parent 2292e2f685
commit 943c15ac1b
1 changed files with 11 additions and 18 deletions
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25
drivers/hwmon/w83791d.c
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@ -273,9 +273,6 @@ struct w83791d_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];
/* volts */
u8 in[NUMBER_OF_VIN]; /* Register value */
u8 in_max[NUMBER_OF_VIN]; /* Register value */
@ -1257,7 +1254,6 @@ static const struct attribute_group w83791d_group_fanpwm45 = {
static int w83791d_detect_subclients(struct i2c_client *client)
{
struct i2c_adapter *adapter = client->adapter;
struct w83791d_data *data = i2c_get_clientdata(client);
int address = client->addr;
int i, id;
u8 val;
@ -1280,21 +1276,18 @@ static int w83791d_detect_subclients(struct i2c_client *client)
}
val = w83791d_read(client, W83791D_REG_I2C_SUBADDR);
if (!(val & 0x08))
data->lm75[0] = devm_i2c_new_dummy_device(&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(&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(&client->dev, adapter,
0x48 + ((val >> 4) & 0x7));
}
if (!(val & 0x08))
devm_i2c_new_dummy_device(&client->dev, adapter, 0x48 + (val & 0x7));
if (!(val & 0x80))
devm_i2c_new_dummy_device(&client->dev, adapter, 0x48 + ((val >> 4) & 0x7));
return 0;
}