[PATCH] iio: buffer: Fix memory leak in iio_buffer_register_legacy_sysfs_groups()

[Yang Yingliang]

If the second iio_device_register_sysfs_group() fails,
'legacy_buffer_group.attrs' need be freed too or it will
cause memory leak:

unreferenced object 0xffff888003618280 (size 64):
  comm "xrun", pid 357, jiffies 4294907259 (age 22.296s)
  hex dump (first 32 bytes):
    80 f6 8c 03 80 88 ff ff 80 fb 8c 03 80 88 ff ff  ................
    00 f9 8c 03 80 88 ff ff 80 fc 8c 03 80 88 ff ff  ................
  backtrace:
    [<00000000076bfd43>] __kmalloc+0x1a3/0x2f0
    [<00000000c32e4886>] iio_buffers_alloc_sysfs_and_mask+0xc31/0x1290 [industrialio]
    [<000000002fcd0bb8>] __iio_device_register+0x52e/0x1b40 [industrialio]
    [<000000008116530c>] __devm_iio_device_register+0x22/0x80 [industrialio]
    [<000000008a47327c>] adjd_s311_probe+0x195/0x200 [adjd_s311]
    [<00000000f8eeb456>] i2c_device_probe+0xa07/0xbb0
    [<000000000e86686c>] really_probe+0x285/0xc30
    [<00000000a49db55c>] __driver_probe_device+0x35f/0x4f0
    [<00000000d1fd43a1>] driver_probe_device+0x4f/0x140
    [<000000008cdafdfa>] __device_attach_driver+0x24c/0x330
    [<000000006466e92e>] bus_for_each_drv+0x15d/0x1e0
    [<00000000154fbb1c>] __device_attach+0x267/0x410
    [<000000007c84d5d1>] bus_probe_device+0x1ec/0x2a0
    [<0000000019967467>] device_add+0xc3d/0x2020
    [<00000000a16d2d51>] i2c_new_client_device+0x614/0xb00
    [<00000000a56a901d>] new_device_store+0x1f4/0x410

Reported-by: Hulk Robot <hulkci@xxxxxxxxxx>
Fixes: d9a625744ed0 ("iio: core: merge buffer/ & scan_elements/ attributes")
Signed-off-by: Yang Yingliang <yangyingliang@xxxxxxxxxx>
---
 drivers/iio/industrialio-buffer.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/iio/industrialio-buffer.c b/drivers/iio/industrialio-buffer.c
index ba1c5c898e53..88741385764e 100644
--- a/drivers/iio/industrialio-buffer.c
+++ b/drivers/iio/industrialio-buffer.c
@@ -1367,10 +1367,10 @@ static int iio_buffer_register_legacy_sysfs_groups(struct iio_dev *indio_dev,
 
 	return 0;
 
-error_free_buffer_attrs:
-	kfree(iio_dev_opaque->legacy_buffer_group.attrs);
 error_free_scan_el_attrs:
 	kfree(iio_dev_opaque->legacy_scan_el_group.attrs);
+error_free_buffer_attrs:
+	kfree(iio_dev_opaque->legacy_buffer_group.attrs);
 
 	return ret;
 }
-- 
2.25.1