lkml.org 
[lkml]   [2019]   [Feb]   [12]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
Date
SubjectRe: [PATCH] pstore/ram: Avoid possible failure of dummy device unregister
On Mon, Jan 21, 2019 at 11:19 PM Yue Hu <huyue2@yulong.com> wrote:
>
> From 7c1f672a2d7b7c2cfef313060bd429afc4af995b Mon Sep 17 00:00:00 2001
> From: Yue Hu <huyue2@yulong.com>
> Date: Tue, 22 Jan 2019 14:47:00 +0800
> Subject: [PATCH] pstore/ram: Avoid possible failure of dummy device unregister
>
> In ramoops_register_dummy() if create platform device of dummy
> failed, the problem is following code called:
>
> dummy = NULL;
> ramoops_unregister_dummy();
>
> However platform_device_unregister() will check the pointer:
>
> void platform_device_del(struct platform_device *pdev)
> {
> int i;
>
> if (pdev) {
> ...
> }
> }
> void platform_device_put(struct platform_device *pdev)
> {
> if (pdev)
> put_device(&pdev->dev);
> }
> void platform_device_unregister(struct platform_device *pdev)
> {
> platform_device_del(pdev);
> platform_device_put(pdev);
> }
>
> So the dummy device maybe always exists in the system, this is bad
> case, we need to avoid it.
>
> Signed-off-by: Yue Hu <huyue2@yulong.com>
> ---
> fs/pstore/ram.c | 1 -
> 1 file changed, 1 deletion(-)
>
> diff --git a/fs/pstore/ram.c b/fs/pstore/ram.c
> index 8db1f7f..1d56a20 100644
> --- a/fs/pstore/ram.c
> +++ b/fs/pstore/ram.c
> @@ -932,7 +932,6 @@ static void __init ramoops_register_dummy(void)
> if (IS_ERR(dummy)) {
> pr_info("could not create platform device: %ld\n",
> PTR_ERR(dummy));
> - dummy = NULL;
> ramoops_unregister_dummy();

No, this needs to be cleared to NULL to avoid leaving a ERR_PTR (which
are non-NULL, see IS_ERR() above it), so that it can be safe to
unconditionally call platform_device_unregister().

--
Kees Cook

\
 
 \ /
  Last update: 2019-02-12 21:17    [W:0.024 / U:3.304 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site