CVE-2022-49285

In the Linux kernel, the following vulnerability has been resolved:

iio: accel: mma8452: use the correct logic to get mma8452_data

The original logic to get mma8452data is wrong, the *dev point to the device belong to iiodev. we can't use this dev to find the correct i2cclient. The original logic happen to work because it finally use dev->driverdata to get iiodev. Here use the API toi2c_client() is wrong and make reader confuse. To correct the logic, it should be like this

struct mma8452data *data = iiopriv(devgetdrvdata(dev));

But after commit 8b7651f25962 ("iio: iiodevicealloc(): Remove unnecessary self drvdata"), the upper logic also can't work. When try to show the avialable scale in userspace, will meet kernel dump, kernel handle NULL pointer dereference.

So use devtoiio_dev() to correct the logic.

Dual fixes tags as the second reflects when the bug was exposed, whilst the first reflects when the original bug was introduced.