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From:   Alexandru Ardelean <ardeleanalex@gmail.com>
Date:   Mon, 18 Oct 2021 09:41:10 +0300
Message-ID: <CA+U=DsorPFMpz3QS=dYrV4_UmeyeZXbS2Afpt7UHCkwo3JEABA@mail.gmail.com>
Subject: Re: [PATCH v2] iio: buffer: Fix memory leak in iio_buffers_alloc_sysfs_and_mask()
To:     Yang Yingliang <yangyingliang@huawei.com>
Cc:     LKML <linux-kernel@vger.kernel.org>,
        linux-iio <linux-iio@vger.kernel.org>,
        Lars-Peter Clausen <lars@metafoo.de>,
        Jonathan Cameron <jic23@kernel.org>
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On Mon, Oct 18, 2021 at 9:29 AM Yang Yingliang <yangyingliang@huawei.com> wrote:
>
> 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.
>

Reviewed- by: Alexandru Ardelean <ardeleanalex@gmail.com>

> Reported-by: Hulk Robot <hulkci@huawei.com>
> Fixes: d9a625744ed0 ("iio: core: merge buffer/ & scan_elements/ attributes")
> Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
> ---
> v2:
>   move iio_buffer_unregister_legacy_sysfs_groups() into
>   __iio_buffer_free_sysfs_and_mask()
> ---
>  drivers/iio/industrialio-buffer.c | 12 +++++++-----
>  1 file changed, 7 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/iio/industrialio-buffer.c b/drivers/iio/industrialio-buffer.c
> index a95cc2da56be..b29d105a75fe 100644
> --- a/drivers/iio/industrialio-buffer.c
> +++ b/drivers/iio/industrialio-buffer.c
> @@ -1583,8 +1583,12 @@ 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);
> @@ -1638,7 +1642,7 @@ 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;
>  }
> @@ -1655,11 +1659,9 @@ 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);
>         }
>  }
>
> --
> 2.25.1
>