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Wed, 11 Aug 2021 11:18:46 -0700 (PDT) Sender: Guenter Roeck Date: Wed, 11 Aug 2021 11:18:44 -0700 From: Guenter Roeck To: Nadezda Lutovinova Cc: Marc Hulsman , Jean Delvare , Rudolf Marek , linux-hwmon@vger.kernel.org, linux-kernel@vger.kernel.org, ldv-project@linuxtesting.org Subject: Re: [PATCH] hwmon: Correct the error handling in w83793.c, w83791d.c, w83792d.c Message-ID: <20210811181844.GB3138792@roeck-us.net> References: <20210811161515.17842-1-lutovinova@ispras.ru> <20210811161515.17842-2-lutovinova@ispras.ru> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210811161515.17842-2-lutovinova@ispras.ru> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Aug 11, 2021 at 07:15:15PM +0300, Nadezda Lutovinova wrote: > If driver read tmp (or val) 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) > > The patch adds checking if data->lm75[0] is NULL. > > Found by Linux Driver Verification project (linuxtesting.org). > One patch per driver, please. > Signed-off-by: Nadezda Lutovinova > --- > drivers/hwmon/w83791d.c | 2 +- > drivers/hwmon/w83792d.c | 2 +- > drivers/hwmon/w83793.c | 2 +- > 3 files changed, 3 insertions(+), 3 deletions(-) > > diff --git a/drivers/hwmon/w83791d.c b/drivers/hwmon/w83791d.c > index 37b25a1474c4..8b30bbfafaa7 100644 > --- a/drivers/hwmon/w83791d.c > +++ b/drivers/hwmon/w83791d.c > @@ -1284,7 +1284,7 @@ static int w83791d_detect_subclients(struct i2c_client *client) > data->lm75[0] = devm_i2c_new_dummy_device(&client->dev, adapter, > 0x48 + (val & 0x7)); > if (!(val & 0x80)) { > - if (!IS_ERR(data->lm75[0]) && > + if (!IS_ERR_OR_NULL(data->lm75[0]) && > ((val & 0x7) == ((val >> 4) & 0x7))) { > dev_err(&client->dev, > "duplicate addresses 0x%x, " As you pointed out in te other e-mail, lm75[] does not really serve a purpose anymore. It might be much better to replace this code with something like 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; } Same for the other chips. Guenter > diff --git a/drivers/hwmon/w83792d.c b/drivers/hwmon/w83792d.c > index abd5c3a722b9..85ae12d950e1 100644 > --- a/drivers/hwmon/w83792d.c > +++ b/drivers/hwmon/w83792d.c > @@ -950,7 +950,7 @@ w83792d_detect_subclients(struct i2c_client *new_client) > data->lm75[0] = devm_i2c_new_dummy_device(&new_client->dev, adapter, > 0x48 + (val & 0x7)); > if (!(val & 0x80)) { > - if (!IS_ERR(data->lm75[0]) && > + if (!IS_ERR_OR_NULL(data->lm75[0]) && > ((val & 0x7) == ((val >> 4) & 0x7))) { > dev_err(&new_client->dev, > "duplicate addresses 0x%x, use force_subclient\n", > diff --git a/drivers/hwmon/w83793.c b/drivers/hwmon/w83793.c > index e7d0484eabe4..9d8c44e2fa6e 100644 > --- a/drivers/hwmon/w83793.c > +++ b/drivers/hwmon/w83793.c > @@ -1590,7 +1590,7 @@ w83793_detect_subclients(struct i2c_client *client) > data->lm75[0] = devm_i2c_new_dummy_device(&client->dev, adapter, > 0x48 + (tmp & 0x7)); > if (!(tmp & 0x80)) { > - if (!IS_ERR(data->lm75[0]) > + if (!IS_ERR_OR_NULL(data->lm75[0]) > && ((tmp & 0x7) == ((tmp >> 4) & 0x7))) { > dev_err(&client->dev, > "duplicate addresses 0x%x, " > -- > 2.17.1 >