From: Hans Verkuil <hverkuil@xs4all.nl>
To: Pan Bian <bianpan2016@163.com>,
Jacob Chen <jacob-chen@iotwrt.com>,
Ezequiel Garcia <ezequiel@collabora.com>,
Mauro Carvalho Chehab <mchehab@kernel.org>,
Heiko Stuebner <heiko@sntech.de>
Cc: linux-rockchip@lists.infradead.org, linux-kernel@vger.kernel.org,
linux-arm-kernel@lists.infradead.org,
linux-media@vger.kernel.org
Subject: Re: [PATCH] media: rockchip/rga: fix potential use after free
Date: Sat, 9 Nov 2019 12:08:01 +0100 [thread overview]
Message-ID: <e89f6a90-4899-0945-e11a-67be6a28e7c0@xs4all.nl> (raw)
In-Reply-To: <1572969354-8967-1-git-send-email-bianpan2016@163.com>
On 11/5/19 4:55 PM, Pan Bian wrote:
> The variable vga->vfd is an alias for vfd. Therefore, releasing vfd and
> then unregister vga->vfd will lead to a use after free bug. In fact, the
> free operation and the unregister operation are reversed.
>
> Signed-off-by: Pan Bian <bianpan2016@163.com>
> ---
> drivers/media/platform/rockchip/rga/rga.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/media/platform/rockchip/rga/rga.c b/drivers/media/platform/rockchip/rga/rga.c
> index e9ff12b6b5bb..613b868fce33 100644
> --- a/drivers/media/platform/rockchip/rga/rga.c
> +++ b/drivers/media/platform/rockchip/rga/rga.c
> @@ -901,9 +901,9 @@ static int rga_probe(struct platform_device *pdev)
> return 0;
>
> rel_vdev:
> - video_device_release(vfd);
> -unreg_video_dev:
> video_unregister_device(rga->vfd);
> +unreg_video_dev:
> + video_device_release(vfd);
> unreg_v4l2_dev:
> v4l2_device_unregister(&rga->v4l2_dev);
> err_put_clk:
>
This isn't right, you need to update the goto labels as well.
With this change unreg_video_dev releases the vdev, while rel_vdev
unregisters it. Very confusing.
I'd also rename unreg_video_dev to unreg_vdev to be consistent with
rel_vdev.
Regards,
Hans
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prev parent reply other threads:[~2019-11-09 11:08 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-05 15:55 [PATCH] media: rockchip/rga: fix potential use after free Pan Bian
2019-11-09 11:08 ` Hans Verkuil [this message]
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