This is a note to let you know that I've just added the patch titled
iio: cros_ec: fix an use-after-free in cros_ec_sensors_push_data()
to the 6.5-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
iio-cros_ec-fix-an-use-after-free-in-cros_ec_sensors_push_data.patch
and it can be found in the queue-6.5 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 7771c8c80d62ad065637ef74ed2962983f6c5f6d Mon Sep 17 00:00:00 2001
From: Tzung-Bi Shih <tzungbi@xxxxxxxxxx>
Date: Tue, 29 Aug 2023 11:06:22 +0800
Subject: iio: cros_ec: fix an use-after-free in cros_ec_sensors_push_data()
From: Tzung-Bi Shih <tzungbi@xxxxxxxxxx>
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.c#L1189
[2]: https://elixir.bootlin.com/linux/v6.5/source/drivers/iio/common/cros_ec_sensors/cros_ec_sensors_core.c#L198
Cc: stable@xxxxxxxxxxxxxxx
Fixes: aa984f1ba4a4 ("iio: cros_ec: Register to cros_ec_sensorhub when EC supports FIFO")
Signed-off-by: Tzung-Bi Shih <tzungbi@xxxxxxxxxx>
Reviewed-by: Guenter Roeck <groeck@xxxxxxxxxxxx>
Reviewed-by: Stephen Boyd <swboyd@xxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20230829030622.1571852-1-tzungbi@xxxxxxxxxx
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
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);
Patches currently in stable-queue which might be from tzungbi@xxxxxxxxxx are
queue-6.5/iio-cros_ec-fix-an-use-after-free-in-cros_ec_sensors_push_data.patch
