6.5-stable review patch. If anyone has any objections, please let me know.
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From: Tzung-Bi Shih tzungbi@kernel.org
commit 7771c8c80d62ad065637ef74ed2962983f6c5f6d upstream.
cros_ec_sensors_push_data() reads `indio_dev->active_scan_mask` and calls iio_push_to_buffers_with_timestamp() without making sure the `indio_dev` stays in buffer mode. There is a race if `indio_dev` exits buffer mode right before cros_ec_sensors_push_data() accesses them.
An use-after-free on `indio_dev->active_scan_mask` was observed. The call trace: [...] _find_next_bit cros_ec_sensors_push_data cros_ec_sensorhub_event blocking_notifier_call_chain cros_ec_irq_thread
It was caused by a race condition: one thread just freed `active_scan_mask` at [1]; while another thread tried to access the memory at [2].
Fix it by calling iio_device_claim_buffer_mode() to ensure the `indio_dev` can't exit buffer mode during cros_ec_sensors_push_data().
[1]: https://elixir.bootlin.com/linux/v6.5/source/drivers/iio/industrialio-buffer... [2]: https://elixir.bootlin.com/linux/v6.5/source/drivers/iio/common/cros_ec_sens...
Cc: stable@vger.kernel.org Fixes: aa984f1ba4a4 ("iio: cros_ec: Register to cros_ec_sensorhub when EC supports FIFO") Signed-off-by: Tzung-Bi Shih tzungbi@kernel.org Reviewed-by: Guenter Roeck groeck@chromium.org Reviewed-by: Stephen Boyd swboyd@chromium.org Link: https://lore.kernel.org/r/20230829030622.1571852-1-tzungbi@kernel.org Signed-off-by: Jonathan Cameron Jonathan.Cameron@huawei.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/iio/common/cros_ec_sensors/cros_ec_sensors_core.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-)
--- a/drivers/iio/common/cros_ec_sensors/cros_ec_sensors_core.c +++ b/drivers/iio/common/cros_ec_sensors/cros_ec_sensors_core.c @@ -190,8 +190,11 @@ int cros_ec_sensors_push_data(struct iio /* * Ignore samples if the buffer is not set: it is needed if the ODR is * set but the buffer is not enabled yet. + * + * Note: iio_device_claim_buffer_mode() returns -EBUSY if the buffer + * is not enabled. */ - if (!iio_buffer_enabled(indio_dev)) + if (iio_device_claim_buffer_mode(indio_dev) < 0) return 0;
out = (s16 *)st->samples; @@ -210,6 +213,7 @@ int cros_ec_sensors_push_data(struct iio iio_push_to_buffers_with_timestamp(indio_dev, st->samples, timestamp + delta);
+ iio_device_release_buffer_mode(indio_dev); return 0; } EXPORT_SYMBOL_GPL(cros_ec_sensors_push_data);