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platform/chrome: sensorhub: Fix memory overread in ring handler

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`max_response` and `sensor_num` are read from different EC commands:

- `max_response` is from cros_ec_get_proto_info().
    ec_dev->max_response = info->max_response_packet_size -
                                    sizeof(struct ec_host_response);

- `sensor_num` is from cros_ec_get_sensor_count().
    sensor_num = cros_ec_get_sensor_count(ec);

With a malfunctioning EC firmware, it is possible that the `msg->insize`
(i.e., `fifo_info_length` in the context) could be clamped in
cros_ec_cmd_xfer() because `msg->insize` is greater than `max_response`.

    int fifo_info_length =
            sizeof(struct ec_response_motion_sense_fifo_info) +
            sizeof(u16) * sensorhub->sensor_num;

This means the number of read bytes could be less than expected.  As a
result, the subsequent memcpy() in cros_ec_sensorhub_ring_handler()
overreads the `resp->fifo_info` buffer.

Check the return value of cros_ec_cmd_xfer_status() and abort if the
number of bytes read does not match the expected length.

Fixes: 145d59baff ("platform/chrome: cros_ec_sensorhub: Add FIFO support")
Reviewed-by: Tomasz Figa <tfiga@chromium.org>
Link: https://lore.kernel.org/r/20260702082745.1014968-1-tzungbi@kernel.org
Signed-off-by: Tzung-Bi Shih <tzungbi@kernel.org>
This commit is contained in:
Tzung-Bi Shih 2026-07-02 08:27:45 +00:00
parent a0a8cd9fc9
commit d1ceb2b232
1 changed files with 8 additions and 1 deletions
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9
drivers/platform/chrome/cros_ec_sensorhub_ring.c
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@ -825,8 +825,15 @@ static void cros_ec_sensorhub_ring_handler(struct cros_ec_sensorhub *sensorhub)
sensorhub->msg->outsize = 1;
sensorhub->msg->insize = fifo_info_length;
if (cros_ec_cmd_xfer_status(ec->ec_dev, sensorhub->msg) < 0)
ret = cros_ec_cmd_xfer_status(ec->ec_dev, sensorhub->msg);
if (ret < 0)
goto error;
if (ret != fifo_info_length) {
dev_warn_ratelimited(sensorhub->dev,
"Mismatch read length: size %d - expected %d\n",
ret, fifo_info_length);
goto error;
}
memcpy(fifo_info, &sensorhub->resp->fifo_info,
fifo_info_length);