Re: NULL pointer dereference in iio_buffer_register()

Fengguang Wu
2012-07-31T12:55:55Z

> > The panic happens while trying to dereference the NULL indio_dev->buffer:
> >
> > 266 int iio_buffer_register(struct iio_dev *indio_dev,
> > 267 const struct iio_chan_spec *channels,
> > 268 int num_channels)
> > 269 {
> > 270 struct iio_dev_attr *p;
> > 271 struct attribute **attr;
> > 272 struct iio_buffer *buffer = indio_dev->buffer;
> > 273 int ret, i, attrn, attrcount, attrcount_orig = 0;
> > 274
> > ==> 275 if (buffer->attrs)
> > 276 indio_dev->groups[indio_dev->groupcounter++] = buffer->attrs;
> >
> > iio_dummy_probe() has the code to configure that buffer, however
> > iio_simple_dummy_configure_buffer() is defined to do nothing on
> > !CONFIG_IIO_SIMPLE_DUMMY_BUFFER..
> >
> > 448 /* Configure buffered capture support. */
> > ==> 449 ret = iio_simple_dummy_configure_buffer(indio_dev);
> > 450 if (ret < 0)
> > 451 goto error_unregister_events;
> > 452
> > 453 /*
> > 454 * Register the channels with the buffer, but avoid the output
> > 455 * channel being registered by reducing the number of channels by 1.
> > 456 */
> > 457 ret = iio_buffer_register(indio_dev, iio_dummy_channels, 5);
> > 458 if (ret < 0)
> > 459 goto error_unconfigure_buffer;
> >
> > Any ideas to fix it?
> >
>
> Hi,
>
> I think the best would be to move the iio_buffer_register to
> iio_simple_dummy_configure_buffer.

Lars, thanks for the quick reply! Hmm, that looks more like a code
refactor recommendation than fix ;) In the simplest form, can the
bug fixed like this?

static inline int iio_simple_dummy_configure_buffer(struct iio_dev *indio_dev)
{
- return 0;
+ return -1;
};

Thanks,
Fengguang