patch "iio: buffer: Fix memory leak in iio_buffers_alloc_sysfs_and_mask()" added to char-misc-testing

This is a note to let you know that I've just added the patch titled

iio: buffer: Fix memory leak in iio_buffers_alloc_sysfs_and_mask()

to my char-misc git tree which can be found at
git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc.git
in the char-misc-testing branch.

The patch will show up in the next release of the linux-next tree (usually sometime within the next 24 hours during the week.)

The patch will be merged to the char-misc-next branch sometime soon, after it passes testing, and the merge window is open.

If you have any questions about this process, please let me know.

From 486a25084155bf633768c26f022201c051d6fd95 Mon Sep 17 00:00:00 2001
From: Yang Yingliang <[email protected]>
Date: Mon, 18 Oct 2021 14:37:18 +0800
Subject: iio: buffer: Fix memory leak in iio_buffers_alloc_sysfs_and_mask()

When 'iio_dev_opaque->buffer_ioctl_handler' alloc fails in iio_buffers_alloc_sysfs_and_mask(), the 'attrs' allocated in iio_buffer_register_legacy_sysfs_groups() will be leaked:

unreferenced object 0xffff888108568d00 (size 128):
comm "88", pid 2014, jiffies 4294963294 (age 26.920s) hex dump (first 32 bytes):

    80 3e da 02 80 88 ff ff 00 3a da 02 80 88 ff ff  .>.......:......
    00 35 da 02 80 88 ff ff 00 38 da 02 80 88 ff ff  .5.......8......
  backtrace:
    [<0000000095a9e51e>] __kmalloc+0x1a3/0x2f0
    [<00000000faa3735e>] iio_buffers_alloc_sysfs_and_mask+0xfa3/0x1480 [industrialio]
    [<00000000a46384dc>] __iio_device_register+0x52e/0x1b40 [industrialio]
    [<00000000210af05e>] __devm_iio_device_register+0x22/0x80 [industrialio]
    [<00000000730d7b41>] adjd_s311_probe+0x195/0x200 [adjd_s311]
    [<00000000c0f70eb9>] i2c_device_probe+0xa07/0xbb0

The iio_buffer_register_legacy_sysfs_groups() is called in __iio_buffer_alloc_sysfs_and_mask(), so move the iio_buffer_unregister_legacy_sysfs_groups() into __iio_buffer_free_sysfs_and_mask(), then the memory will be freed.

---
 drivers/iio/industrialio-buffer.c | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

index 1c3972150ab4..2f98ba70e3d7 100644
@@ -1587,8 +1587,12 @@ static int __iio_buffer_alloc_sysfs_and_mask(struct iio_buffer *buffer,
 	return ret;
 }
 
-static void __iio_buffer_free_sysfs_and_mask(struct iio_buffer *buffer)
+static void __iio_buffer_free_sysfs_and_mask(struct iio_buffer *buffer,
+					     struct iio_dev *indio_dev,
+					     int index)
 {
+	if (index == 0)
+		iio_buffer_unregister_legacy_sysfs_groups(indio_dev);
 	bitmap_free(buffer->scan_mask);
 	kfree(buffer->buffer_group.name);
 	kfree(buffer->buffer_group.attrs);

@@ -1642,7 +1646,7 @@ int iio_buffers_alloc_sysfs_and_mask(struct iio_dev *indio_dev)
 error_unwind_sysfs_and_mask:
 	for (; unwind_idx >= 0; unwind_idx--) {
 		buffer = iio_dev_opaque->attached_buffers[unwind_idx];
-		__iio_buffer_free_sysfs_and_mask(buffer);
+		__iio_buffer_free_sysfs_and_mask(buffer, indio_dev, unwind_idx);
 	}
 	return ret;
 }

@@ -1659,11 +1663,9 @@ void iio_buffers_free_sysfs_and_mask(struct iio_dev *indio_dev)
 	iio_device_ioctl_handler_unregister(iio_dev_opaque->buffer_ioctl_handler);
 	kfree(iio_dev_opaque->buffer_ioctl_handler);
 
-	iio_buffer_unregister_legacy_sysfs_groups(indio_dev);
-
 	for (i = iio_dev_opaque->attached_buffers_cnt - 1; i >= 0; i--) {
 		buffer = iio_dev_opaque->attached_buffers[i];
-		__iio_buffer_free_sysfs_and_mask(buffer);
+		__iio_buffer_free_sysfs_and_mask(buffer, indio_dev, i);
 	}
 }
 

2.33.1