Re: [PATCH] iio: trigger: sysfs: fix possible memory leak in iio_sysfs_trig_init()

[Jonathan Cameron <jic23@kernel.org>]

On Sat, 22 Oct 2022 15:42:12 +0800
Yang Yingliang <yangyingliang@huawei.com> wrote:

> dev_set_name() allocates memory for name, it need be freed
> when device_add() fails, call put_device() to give up the
> reference that hold in device_initialize(), so that it can
> be freed in kobject_cleanup() when the refcount hit to 0.
> 
> Fault injection test can trigger this:
> 
> unreferenced object 0xffff8e8340a7b4c0 (size 32):
>   comm "modprobe", pid 243, jiffies 4294678145 (age 48.845s)
>   hex dump (first 32 bytes):
>     69 69 6f 5f 73 79 73 66 73 5f 74 72 69 67 67 65  iio_sysfs_trigge
>     72 00 a7 40 83 8e ff ff 00 86 13 c4 f6 ee ff ff  r..@............
>   backtrace:
>     [<0000000074999de8>] __kmem_cache_alloc_node+0x1e9/0x360
>     [<00000000497fd30b>] __kmalloc_node_track_caller+0x44/0x1a0
>     [<000000003636c520>] kstrdup+0x2d/0x60
>     [<0000000032f84da2>] kobject_set_name_vargs+0x1e/0x90
>     [<0000000092efe493>] dev_set_name+0x4e/0x70
> 
> Fixes: 1f785681a870 ("staging:iio:trigger sysfs userspace trigger rework.")
> Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
Applied to the fixes-togreg branch of iio.git and marked for stable.

Thanks,

Jonathan

> ---
>  drivers/iio/trigger/iio-trig-sysfs.c | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/iio/trigger/iio-trig-sysfs.c b/drivers/iio/trigger/iio-trig-sysfs.c
> index d6c5e9644738..6b05eed41612 100644
> --- a/drivers/iio/trigger/iio-trig-sysfs.c
> +++ b/drivers/iio/trigger/iio-trig-sysfs.c
> @@ -203,9 +203,13 @@ static int iio_sysfs_trigger_remove(int id)
>  
>  static int __init iio_sysfs_trig_init(void)
>  {
> +	int ret;
>  	device_initialize(&iio_sysfs_trig_dev);
>  	dev_set_name(&iio_sysfs_trig_dev, "iio_sysfs_trigger");
> -	return device_add(&iio_sysfs_trig_dev);
> +	ret = device_add(&iio_sysfs_trig_dev);
> +	if (ret)
> +		put_device(&iio_sysfs_trig_dev);
> +	return ret;
>  }
>  module_init(iio_sysfs_trig_init);
>