iio: fix memory leak in iio_device_register_eventset()

commit 86fdd15 upstream.

When iio_device_register_sysfs_group() returns failed,
iio_device_register_eventset() needs to free attrs array.

Otherwise, kmemleak would scan & report memory leak as below:

unreferenced object 0xffff88810a1cc3c0 (size 32):
  comm "100-i2c-vcnl302", pid 728, jiffies 4295052307 (age 156.027s)
  backtrace:
    __kmalloc+0x46/0x1b0
    iio_device_register_eventset at drivers/iio/industrialio-event.c:541
    __iio_device_register at drivers/iio/industrialio-core.c:1959
    __devm_iio_device_register at drivers/iio/industrialio-core.c:2040

Fixes: 32f1717 ("iio: core: rework iio device group creation")
Signed-off-by: Zeng Heng <zengheng4@huawei.com>
Link: https://lore.kernel.org/r/20221115023712.3726854-1-zengheng4@huawei.com
Cc: <Stable@vger.kernel.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/iio/industrialio-event.c

@@ -549,14 +549,16 @@ int iio_device_register_eventset(struct iio_dev *indio_dev)
 
 	ret = iio_device_register_sysfs_group(indio_dev, &ev_int->group);
 	if (ret)
-		goto error_free_setup_event_lines;
+		goto error_free_group_attrs;
 
 	ev_int->ioctl_handler.ioctl = iio_event_ioctl;
 	iio_device_ioctl_handler_register(&iio_dev_opaque->indio_dev,
 					  &ev_int->ioctl_handler);
 
 	return 0;
 
+error_free_group_attrs:
+	kfree(ev_int->group.attrs);
 error_free_setup_event_lines:
 	iio_free_chan_devattr_list(&ev_int->dev_attr_list);
 	kfree(ev_int);