From: Nadezda Lutovinova <lutovinova@xxxxxxxxx> commit 943c15ac1b84d378da26bba41c83c67e16499ac4 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@xxxxxxxxxxxxxxx Signed-off-by: Nadezda Lutovinova <lutovinova@xxxxxxxxx> Link: https://lore.kernel.org/r/20210921155153.28098-1-lutovinova@xxxxxxxxx [groeck: Dropped unnecessary continuation lines, fixed multi-line alignment] Signed-off-by: Guenter Roeck <linux@xxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/hwmon/w83791d.c | 29 +++++++++++------------------ 1 file changed, 11 insertions(+), 18 deletions(-) --- a/drivers/hwmon/w83791d.c +++ b/drivers/hwmon/w83791d.c @@ -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 w837 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; @@ -1280,22 +1276,19 @@ static int w83791d_detect_subclients(str } 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))) { - dev_err(&client->dev, - "duplicate addresses 0x%x, " - "use force_subclient\n", - data->lm75[0]->addr); - return -ENODEV; - } - data->lm75[1] = devm_i2c_new_dummy_device(&client->dev, adapter, - 0x48 + ((val >> 4) & 0x7)); + + if (!(val & 0x88) && (val & 0x7) == ((val >> 4) & 0x7)) { + dev_err(&client->dev, + "duplicate addresses 0x%x, use force_subclient\n", 0x48 + (val & 0x7)); + return -ENODEV; } + 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; }
