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iio: buffer: Fix NULL pointer deref caused by empty scan mask 

iio_scan_mask_match() returns NULL if the passed in scan mask is empty. This
will happen if no channel has been selected and buffer is enabled.
iio_sw_buffer_preenable() will assign NULL to indio_dev->active_scan_mask in
this case. As a result iio_update_demux() will cause a NULL pointer deref,
because it expects active_scan_mask to be non-NULL.

Since it does not make much sense to start data capture if there is no data to
capture this patch updates the code to fail gracefully in iio_scan_mask_match()
instead of crashing the kernel.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Acked-by: Jonathan Cameron <jic23@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Lars-Peter Clausen 2012-06-15 18:08:59 +02:00 committed by Greg Kroah-Hartman
parent fb1c4bcd72
commit aff1eb4e3d
1 changed files with 4 additions and 0 deletions
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4
drivers/iio/industrialio-buffer.c
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@ -553,6 +553,10 @@ int iio_sw_buffer_preenable(struct iio_dev *indio_dev)
buffer->scan_mask);
else
indio_dev->active_scan_mask = buffer->scan_mask;
if (indio_dev->active_scan_mask == NULL)
return -EINVAL;
iio_update_demux(indio_dev);
if (indio_dev->info->update_scan_mode)