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iio: inkern: only release the device node when done with it

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'of_node_put()' can potentially release the memory pointed to by
'iiospec.np' which would leave us with an invalid pointer (and we would
still pass it in 'of_xlate()'). Note that it is not guaranteed for the
of_node lifespan to be attached to the device (to which is attached)
lifespan so that there is (even though very unlikely) the possibility
for the node to be freed while the device is still around. Thus, as there
are indeed some of_xlate users which do access the node, a race is indeed
possible.

As such, we can only release the node after we are done with it.

Fixes: 17d82b47a215d ("iio: Add OF support")
Signed-off-by: Nuno Sá <nuno.sa@analog.com>
Link: https://lore.kernel.org/r/20220715122903.332535-2-nuno.sa@analog.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
This commit is contained in:
Nuno Sá 2022-07-15 14:28:49 +02:00 committed by Jonathan Cameron
parent 15b2ac6785
commit 79c3e84874
1 changed files with 4 additions and 2 deletions
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6
drivers/iio/inkern.c
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@ -165,9 +165,10 @@ static int __of_iio_channel_get(struct iio_channel *channel,
idev = bus_find_device(&iio_bus_type, NULL, iiospec.np,
iio_dev_node_match);
of_node_put(iiospec.np);
if (idev == NULL)
if (idev == NULL) {
of_node_put(iiospec.np);
return -EPROBE_DEFER;
}
indio_dev = dev_to_iio_dev(idev);
channel->indio_dev = indio_dev;
@ -175,6 +176,7 @@ static int __of_iio_channel_get(struct iio_channel *channel,
index = indio_dev->info->of_xlate(indio_dev, &iiospec);
else
index = __of_iio_simple_xlate(indio_dev, &iiospec);
of_node_put(iiospec.np);
if (index < 0)
goto err_put;
channel->channel = &indio_dev->channels[index];