iio: inv_mpu6050: Fix use-after-free in ACPI code

In some cases this can result in incorrectly returning a negative value
from asus_acpi_get_sensor_info and the AK8963 magnetometer failing to
show up.

Note cpm is an alias for buffer.pointer which isn't apparent in this
patch on it's own.

Cc: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Signed-off-by: Crestez Dan Leonard <leonard.crestez@intel.com>
Acked-by: Daniel Baluta <daniel.baluta@intel.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

1 files changed, 3 insertions, 2 deletions

diff --git a/drivers/iio/imu/inv_mpu6050/inv_mpu_acpi.c b/drivers/iio/imu/inv_mpu6050/inv_mpu_acpi.c
index f62b8bd9ad7e..dd6fc6d21f9d 100644
--- a/drivers/iio/imu/inv_mpu6050/inv_mpu_acpi.c
+++ b/drivers/iio/imu/inv_mpu6050/inv_mpu_acpi.c
@@ -56,6 +56,7 @@ static int asus_acpi_get_sensor_info(struct acpi_device *adev,
         int i;
         acpi_status status;
         union acpi_object *cpm;
+        int ret;
 
         status = acpi_evaluate_object(adev->handle, "CNF0", NULL, &buffer);
         if (ACPI_FAILURE(status))
@@ -82,10 +83,10 @@ static int asus_acpi_get_sensor_info(struct acpi_device *adev,
                         }
                 }
         }
-
+        ret = cpm->package.count;
         kfree(buffer.pointer);
 
-        return cpm->package.count;
+        return ret;
 }
 
 static int acpi_i2c_check_resource(struct acpi_resource *ares, void *data)