Re: [PATCH v2] driver: uio: fix possible memory leak and use-after-free in __uio_register_device

[Hamish Martin]

On Fri, 2019-01-04 at 22:19 +0800, liujian wrote:
> 'idev' is malloced in __uio_register_device() and leak free it before
> leaving from the uio_get_minor() error handing case, it will cause
> memory leak.
> 
> Also, in uio_dev_add_attributes() error handing case, idev is used
> after
> device_unregister(), in which 'idev' has been released, touch idev
> cause
> use-after-free.
> 
> Fixes: a93e7b331568 ("uio: Prevent device destruction while fds are
> open")
> Fixes: e6789cd3dfb5 ("uio: Simplify uio error path by using devres
> functions")
> Signed-off-by: liujian <liujian56@xxxxxxxxxx>
> ---
> v1->v2:
> change git log and fix code
> 
> Âdrivers/uio/uio.c | 10 +++++++---
> Â1 file changed, 7 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/uio/uio.c b/drivers/uio/uio.c
> index 1313422..be2a943 100644
> --- a/drivers/uio/uio.c
> +++ b/drivers/uio/uio.c
> @@ -940,9 +940,12 @@ int __uio_register_device(struct module *owner,
> Â	atomic_set(&idev->event, 0);
> Â
> Â	ret = uio_get_minor(idev);
> -	if (ret)
> +	if (ret) {
> +		kfree(idev);
> Â		return ret;
> +	}
> Â
> +	device_initialize(&idev->dev);
> Â	idev->dev.devt = MKDEV(uio_major, idev->minor);
> Â	idev->dev.class = &uio_class;
> Â	idev->dev.parent = parent;
> @@ -953,7 +956,7 @@ int __uio_register_device(struct module *owner,
> Â	if (ret)
> Â		goto err_device_create;
> Â
> -	ret = device_register(&idev->dev);
> +	ret = device_add(&idev->dev);
> Â	if (ret)
> Â		goto err_device_create;
> Â
> @@ -985,9 +988,10 @@ int __uio_register_device(struct module *owner,
> Âerr_request_irq:
> Â	uio_dev_del_attributes(idev);
> Âerr_uio_dev_add_attributes:
> -	device_unregister(&idev->dev);
> +	device_del(&idev->dev);
> Âerr_device_create:
> Â	uio_free_minor(idev);
> +	put_device(&idev->dev);
> Â	return ret;
> Â}
> ÂEXPORT_SYMBOL_GPL(__uio_register_device);

Looks good to me. Thanks for dealing with those issues.
Reviewed-by: Hamish Martin <hamish.martin@xxxxxxxxxxxxxxxxxxx>