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hwmon: (w83792d) Fix NULL pointer dereference by removing unnecessary structure field

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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: Nadezda 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: 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 18:51:52 +03:00 committed by Greg Kroah-Hartman
parent 6cb01fe630
commit 200ced5ba7
1 changed files with 11 additions and 17 deletions
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28
drivers/hwmon/w83792d.c
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@ -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) {
@ -947,21 +943,19 @@ 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))) {
dev_err(&new_client->dev,
"duplicate addresses 0x%x, use force_subclient\n",
data->lm75[0]->addr);
return -ENODEV;
}
data->lm75[1] = devm_i2c_new_dummy_device(&new_client->dev, adapter,
0x48 + ((val >> 4) & 0x7));
if (!(val & 0x88) && (val & 0x7) == ((val >> 4) & 0x7)) {
dev_err(&new_client->dev,
"duplicate addresses 0x%x, use force_subclient\n", 0x48 + (val & 0x7));
return -ENODEV;
}
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;
}