On Tue, 29 Aug 2023 13:50:59 -0700 Guenter Roeck groeck@google.com wrote:
On Mon, Aug 28, 2023 at 8:06 PM Tzung-Bi Shih tzungbi@kernel.org wrote:
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().
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
Applied to the fixes-togreg branch of iio.git. Note I'll be rebasing that tree on rc1 before I send a pull request. So this will take a week or two to go upstream.
Thanks,
Jonathan
Changes from v1(https://patchwork.kernel.org/project/linux-iio/patch/20230828094339.1248472-...):
- Use iio_device_{claim|release}_buffer_mode() instead of accessing `mlock`.
drivers/iio/common/cros_ec_sensors/cros_ec_sensors_core.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/drivers/iio/common/cros_ec_sensors/cros_ec_sensors_core.c b/drivers/iio/common/cros_ec_sensors/cros_ec_sensors_core.c index b72d39fc2434..6bfe5d6847e7 100644 --- 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_dev *indio_dev, /* * 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_dev *indio_dev, 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); -- 2.42.0.rc2.253.gd59a3bf2b4-goog