In the Linux kernel, the following vulnerability has been resolved: platform/chrome: sensorhub: Fix memory overread in ring handler `max_r

In the Linux kernel, the following vulnerability has been resolved:

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

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.

 1int fifo_info_length =
 2        sizeof(struct ec_response_motion_sense_fifo_info) +
 3        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.