From patchwork Tue Aug 29 03:06:22 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Tzung-Bi Shih X-Patchwork-Id: 13368536 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 47F5AA47 for ; Tue, 29 Aug 2023 03:06:46 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id EB733C433C7; Tue, 29 Aug 2023 03:06:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1693278406; bh=QKe8SUE1Ew+GerDkUiq65QOLr+UYSEHt3K5MUDwaSC0=; h=From:To:Cc:Subject:Date:From; b=cpv9R3GNpa4yz4bv0ge0kjV1mTzL8SX4F9ply1yWfryfW5SlOPPpj1gRR4N/mPvs/ FbLr8VPD8GxTEeKz3qH89hZ18pJM+AUezgYWb+FCxWlxV5f4XHtuoz1d6yQq6XoXF/ XviRCxp+PI4ORKolz1XwIzVXh1PgtQzkGkThoPqDwRTBIzeiONillc3eUF3K+nyCX2 5Lm8uOAqA0ZmMaPTY9yg68oAmgr9aGqq/tLy8C9peEaQtdv1Z1Ubl+M0HURFKwhzs9 TXz27/7KIkkbyM4zZIJFIQf/W0wxhI1H9PxZqprFi6QZS2ALQGuHa3ZofWWjHRPkNE 57dPr4GvFGDag== From: Tzung-Bi Shih To: bleung@chromium.org, groeck@chromium.org, jic23@kernel.org, lars@metafoo.de Cc: chrome-platform@lists.linux.dev, tzungbi@kernel.org, gwendal@chromium.org, linux-iio@vger.kernel.org, dianders@chromium.org, swboyd@chromium.org, stable@vger.kernel.org Subject: [PATCH v2] iio: cros_ec: fix an use-after-free in cros_ec_sensors_push_data() Date: Tue, 29 Aug 2023 11:06:22 +0800 Message-ID: <20230829030622.1571852-1-tzungbi@kernel.org> X-Mailer: git-send-email 2.42.0.rc2.253.gd59a3bf2b4-goog Precedence: bulk X-Mailing-List: chrome-platform@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 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@vger.kernel.org Fixes: aa984f1ba4a4 ("iio: cros_ec: Register to cros_ec_sensorhub when EC supports FIFO") Signed-off-by: Tzung-Bi Shih Reviewed-by: Stephen Boyd Reviewed-by: Guenter Roeck --- Changes from v1(https://patchwork.kernel.org/project/linux-iio/patch/20230828094339.1248472-1-tzungbi@kernel.org/): - 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);