linux-kernel - Re: [PATCH] media: fix null pointer dereference in v4l_vb2q_enable_media

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Date:	Fri, 4 Mar 2016 06:34:04 +0200
From:	Olli Salonen <olli.salonen@....fi>
To:	Shuah Khan <shuahkh@....samsung.com>
Cc:	Mauro Carvalho Chehab <mchehab@....samsung.com>,
	linux-media <linux-media@...r.kernel.org>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] media: fix null pointer dereference in v4l_vb2q_enable_media_source()

Hi Shuah,

Thanks for your quick reaction. This patch seems to fix the oops I got earlier.

Tested-by: Olli Salonen <olli.salonen@....fi>

Cheers,
-olli

On 4 March 2016 at 04:24, Shuah Khan <shuahkh@....samsung.com> wrote:
> Fix the null pointer dereference in v4l_vb2q_enable_media_source().
> DVB only drivers don't have valid struct v4l2_fh pointer.
>
> [  548.443272] BUG: unable to handle kernel NULL pointer dereference
> at 0000000000000010
> [  548.452036] IP: [<ffffffffc020ffc9>]
> v4l_vb2q_enable_media_source+0x9/0x50 [videodev]
> [  548.460792] PGD b820e067 PUD bb3df067 PMD 0
> [  548.465582] Oops: 0000 [#1] SMP
>
> Signed-off-by: Shuah Khan <shuahkh@....samsung.com>
> Reported-by: Olli Salonen <olli.salonen@....fi>
> ---
>  drivers/media/v4l2-core/v4l2-mc.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/media/v4l2-core/v4l2-mc.c b/drivers/media/v4l2-core/v4l2-mc.c
> index 643686d..a39a3cd 100644
> --- a/drivers/media/v4l2-core/v4l2-mc.c
> +++ b/drivers/media/v4l2-core/v4l2-mc.c
> @@ -214,6 +214,8 @@ int v4l_vb2q_enable_media_source(struct vb2_queue *q)
>  {
>         struct v4l2_fh *fh = q->owner;
>
> -       return v4l_enable_media_source(fh->vdev);
> +       if (fh && fh->vdev)
> +               return v4l_enable_media_source(fh->vdev);
> +       return 0;
>  }
>  EXPORT_SYMBOL_GPL(v4l_vb2q_enable_media_source);
> --
> 2.5.0
>