linux-kernel - Re: [PATCH] media: v4l2-dev: fix error handling in __video_register

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <Z9KvJteBVuPE8Hrs@kekkonen.localdomain>
Date: Thu, 13 Mar 2025 10:10:46 +0000
From: Sakari Ailus <sakari.ailus@...ux.intel.com>
To: Ma Ke <make24@...as.ac.cn>
Cc: mchehab@...nel.org, hverkuil@...all.nl, viro@...iv.linux.org.uk,
	bartosz.golaszewski@...aro.org, benjamin.gaignard@...labora.com,
	hljunggr@...co.com, linux-media@...r.kernel.org,
	linux-kernel@...r.kernel.org, stable@...r.kernel.org
Subject: Re: [PATCH] media: v4l2-dev: fix error handling in
 __video_register_device()

Hi Ma,

Thanks for the patch.

On Thu, Mar 13, 2025 at 03:43:18PM +0800, Ma Ke wrote:
> Once device_register() failed, we should call put_device() to
> decrement reference count for cleanup. Or it could cause memory leak.
> 
> As comment of device_register() says, 'NOTE: _Never_ directly free
> @dev after calling this function, even if it returned an error! Always
> use put_device() to give up the reference initialized in this function
> instead.'
> 
> Found by code review.
> 
> Cc: stable@...r.kernel.org
> Fixes: baa057e29b58 ("media: v4l2-dev: use pr_foo() for printing messages")
> Signed-off-by: Ma Ke <make24@...as.ac.cn>
> ---
>  drivers/media/v4l2-core/v4l2-dev.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/media/v4l2-core/v4l2-dev.c b/drivers/media/v4l2-core/v4l2-dev.c
> index 5bcaeeba4d09..1619614e96bf 100644
> --- a/drivers/media/v4l2-core/v4l2-dev.c
> +++ b/drivers/media/v4l2-core/v4l2-dev.c
> @@ -1060,6 +1060,7 @@ int __video_register_device(struct video_device *vdev,
>  	if (ret < 0) {
>  		mutex_unlock(&videodev_lock);
>  		pr_err("%s: device_register failed\n", __func__);
> +		put_device(&vdev->dev);

Fixing this isn't quite as simple. The release callback is actually set
below so there's no release callback set for this device yet.

>  		goto cleanup;
>  	}
>  	/* Register the release callback that will be called when the last

-- 
Kind regards,

Sakari Ailus