[PATCH] iio: accel: mma9551_core: Prevent uninitialized variable in mma9551_read_config_word()

[PATCH] iio: accel: mma9551_core: Prevent uninitialized variable in mma9551_read_config_word()

[Harshit Mogalapalli]

Smatch Warns:
drivers/iio/accel/mma9551_core.c:299
	mma9551_read_config_word() error: uninitialized symbol 'v'.

When (offset >= 1 << 12) is true mma9551_transfer() will return -EINVAL
without 'v' being initialized, so check for the error and return.

Fixes: 40cb761306d6 ("iio: add driver for Freescale MMA9553")
Signed-off-by: Harshit Mogalapalli <harshit.m.mogalapalli@oracle.com>
---
This is detected using static analysis.
---
 drivers/iio/accel/mma9551_core.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/iio/accel/mma9551_core.c b/drivers/iio/accel/mma9551_core.c
index 64ca7d7a9673..75eee7f7303a 100644
--- a/drivers/iio/accel/mma9551_core.c
+++ b/drivers/iio/accel/mma9551_core.c
@@ -296,9 +296,12 @@ int mma9551_read_config_word(struct i2c_client *client, u8 app_id,
 
 	ret = mma9551_transfer(client, app_id, MMA9551_CMD_READ_CONFIG,
 			       reg, NULL, 0, (u8 *)&v, 2);
+	if (ret < 0)
+		return ret;
+
 	*val = be16_to_cpu(v);
 
-	return ret;
+	return 0;
 }
 EXPORT_SYMBOL_NS(mma9551_read_config_word, IIO_MMA9551);
 
-- 
2.38.1

Re: [PATCH] iio: accel: mma9551_core: Prevent uninitialized variable in mma9551_read_config_word()

[Jonathan Cameron]

On Thu, 26 Jan 2023 07:36:09 -0800
Harshit Mogalapalli <harshit.m.mogalapalli@oracle.com> wrote:

> Smatch Warns:
> drivers/iio/accel/mma9551_core.c:299
> 	mma9551_read_config_word() error: uninitialized symbol 'v'.
> 
> When (offset >= 1 << 12) is true mma9551_transfer() will return -EINVAL
> without 'v' being initialized, so check for the error and return.
> 
> Fixes: 40cb761306d6 ("iio: add driver for Freescale MMA9553")
> Signed-off-by: Harshit Mogalapalli <harshit.m.mogalapalli@oracle.com>

Similar to previous.  It's tidying up an inelegant bit of code, but no
actual bug due to checks at the caller.  Hence I've dropped the fixes
tag and added a note to the commit description for anyone considering backporting.

Applied to the togreg branch of iio.git and pushed out as testing for
0-day to take a look at it and see if we missed anything.

Thanks,

Jonathan

> ---
> This is detected using static analysis.
> ---
>  drivers/iio/accel/mma9551_core.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/iio/accel/mma9551_core.c b/drivers/iio/accel/mma9551_core.c
> index 64ca7d7a9673..75eee7f7303a 100644
> --- a/drivers/iio/accel/mma9551_core.c
> +++ b/drivers/iio/accel/mma9551_core.c
> @@ -296,9 +296,12 @@ int mma9551_read_config_word(struct i2c_client *client, u8 app_id,
>  
>  	ret = mma9551_transfer(client, app_id, MMA9551_CMD_READ_CONFIG,
>  			       reg, NULL, 0, (u8 *)&v, 2);
> +	if (ret < 0)
> +		return ret;
> +
>  	*val = be16_to_cpu(v);
>  
> -	return ret;
> +	return 0;
>  }
>  EXPORT_SYMBOL_NS(mma9551_read_config_word, IIO_MMA9551);
>