From 2adb3f8bcc29a0b3c885fdb7e90ccd3228e1b23e Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Nuno=20S=C3=A1?= Date: Thu, 12 Nov 2020 15:43:22 +0100 Subject: [PATCH] iio: buffer: Fix demux update MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit commit 19ef7b70ca9487773c29b449adf0c70f540a0aab upstream. When updating the buffer demux, we will skip a scan element from the device in the case `in_ind != out_ind` and we enter the while loop. in_ind should only be refreshed with `find_next_bit()` in the end of the loop. Note, to cause problems we need a situation where we are skippig over an element (channel not enabled) that happens to not have the same size as the next element. Whilst this is a possible situation we haven't actually identified any cases in mainline where it happens as most drivers have consistent channel storage sizes with the exception of the timestamp which is the last element and hence never skipped over. Fixes: 5ada4ea9be16 ("staging:iio: add demux optionally to path from device to buffer") Signed-off-by: Nuno Sá Link: https://lore.kernel.org/r/20201112144323.28887-1-nuno.sa@analog.com Cc: Signed-off-by: Jonathan Cameron Signed-off-by: Greg Kroah-Hartman --- drivers/iio/industrialio-buffer.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/drivers/iio/industrialio-buffer.c b/drivers/iio/industrialio-buffer.c index a4f6bb96d4f4..276b609d7917 100644 --- a/drivers/iio/industrialio-buffer.c +++ b/drivers/iio/industrialio-buffer.c @@ -865,12 +865,12 @@ static int iio_buffer_update_demux(struct iio_dev *indio_dev, indio_dev->masklength, in_ind + 1); while (in_ind != out_ind) { - in_ind = find_next_bit(indio_dev->active_scan_mask, - indio_dev->masklength, - in_ind + 1); length = iio_storage_bytes_for_si(indio_dev, in_ind); /* Make sure we are aligned */ in_loc = roundup(in_loc, length) + length; + in_ind = find_next_bit(indio_dev->active_scan_mask, + indio_dev->masklength, + in_ind + 1); } length = iio_storage_bytes_for_si(indio_dev, in_ind); out_loc = roundup(out_loc, length);