[PATCH v2] media: vcodec: Fix potential array out-of-bounds in encoder queue_setup

[PATCH v2] media: vcodec: Fix potential array out-of-bounds in encoder queue_setup

[Wei Chen]

variable *nplanes is provided by user via system call argument. The
possible value of q_data->fmt->num_planes is 1-3, while the value
of *nplanes can be 1-8. The array access by index i can cause array
out-of-bounds.

Fix this bug by checking *nplanes against the array size.

Fixes: 4e855a6efa54 ("[media] vcodec: mediatek: Add Mediatek V4L2 Video Encoder Driver")
Signed-off-by: Wei Chen <harperchen1110@gmail.com>
Cc: stable@vger.kernel.org
---
Changes in v2:
- Add Fixes tag and CC stable email address
- Change the title to be more expressive

 drivers/media/platform/mediatek/vcodec/mtk_vcodec_enc.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/media/platform/mediatek/vcodec/mtk_vcodec_enc.c b/drivers/media/platform/mediatek/vcodec/mtk_vcodec_enc.c
index 9ff439a50f53..9e8817863cb8 100644
--- a/drivers/media/platform/mediatek/vcodec/mtk_vcodec_enc.c
+++ b/drivers/media/platform/mediatek/vcodec/mtk_vcodec_enc.c
@@ -821,6 +821,8 @@ static int vb2ops_venc_queue_setup(struct vb2_queue *vq,
 		return -EINVAL;
 
 	if (*nplanes) {
+		if (*nplanes != q_data->fmt->num_planes)
+			return -EINVAL;
 		for (i = 0; i < *nplanes; i++)
 			if (sizes[i] < q_data->sizeimage[i])
 				return -EINVAL;
-- 
2.25.1

Re: [PATCH v2] media: vcodec: Fix potential array out-of-bounds in encoder queue_setup

[Chen-Yu Tsai]

On Thu, Aug 10, 2023 at 4:23 PM Wei Chen <harperchen1110@gmail.com> wrote:
>
> variable *nplanes is provided by user via system call argument. The
> possible value of q_data->fmt->num_planes is 1-3, while the value
> of *nplanes can be 1-8. The array access by index i can cause array
> out-of-bounds.
>
> Fix this bug by checking *nplanes against the array size.
>
> Fixes: 4e855a6efa54 ("[media] vcodec: mediatek: Add Mediatek V4L2 Video Encoder Driver")
> Signed-off-by: Wei Chen <harperchen1110@gmail.com>
> Cc: stable@vger.kernel.org

Reviewed-by: Chen-Yu Tsai <wenst@chromium.org>

Re: [PATCH v2] media: vcodec: Fix potential array out-of-bounds in encoder queue_setup

[Eugen Hristev]

Hi Wei,

On 8/10/23 11:23, Wei Chen wrote:
> variable *nplanes is provided by user via system call argument. The
> possible value of q_data->fmt->num_planes is 1-3, while the value
> of *nplanes can be 1-8. The array access by index i can cause array
> out-of-bounds.
> 
> Fix this bug by checking *nplanes against the array size.
> 
> Fixes: 4e855a6efa54 ("[media] vcodec: mediatek: Add Mediatek V4L2 Video Encoder Driver")
> Signed-off-by: Wei Chen <harperchen1110@gmail.com>
> Cc: stable@vger.kernel.org
> ---
> Changes in v2:
> - Add Fixes tag and CC stable email address
I guess stable needs to be added by the maintainer, not by the submitter

> - Change the title to be more expressive

Subject message should include mediatek I believe, as `media: vcodec:` 
does not reference the mediatek vcodec.

> 
>   drivers/media/platform/mediatek/vcodec/mtk_vcodec_enc.c | 2 ++
>   1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/media/platform/mediatek/vcodec/mtk_vcodec_enc.c b/drivers/media/platform/mediatek/vcodec/mtk_vcodec_enc.c
> index 9ff439a50f53..9e8817863cb8 100644
> --- a/drivers/media/platform/mediatek/vcodec/mtk_vcodec_enc.c
> +++ b/drivers/media/platform/mediatek/vcodec/mtk_vcodec_enc.c
> @@ -821,6 +821,8 @@ static int vb2ops_venc_queue_setup(struct vb2_queue *vq,
>   		return -EINVAL;
>   
>   	if (*nplanes) {
> +		if (*nplanes != q_data->fmt->num_planes)
> +			return -EINVAL;

Have you run v4l2-compliance on the device to make sure nothing is broken ?

>   		for (i = 0; i < *nplanes; i++)
>   			if (sizes[i] < q_data->sizeimage[i])
>   				return -EINVAL;


Greetings,

Re: [PATCH v2] media: vcodec: Fix potential array out-of-bounds in encoder queue_setup

[Nicolas Dufresne]

Hi,

Le jeudi 10 août 2023 à 08:23 +0000, Wei Chen a écrit :
> variable *nplanes is provided by user via system call argument. The
> possible value of q_data->fmt->num_planes is 1-3, while the value
> of *nplanes can be 1-8. The array access by index i can cause array
> out-of-bounds.
> 
> Fix this bug by checking *nplanes against the array size.
> 
> Fixes: 4e855a6efa54 ("[media] vcodec: mediatek: Add Mediatek V4L2 Video Encoder Driver")
> Signed-off-by: Wei Chen <harperchen1110@gmail.com>
> Cc: stable@vger.kernel.org
> ---
> Changes in v2:
> - Add Fixes tag and CC stable email address
> - Change the title to be more expressive
> 
>  drivers/media/platform/mediatek/vcodec/mtk_vcodec_enc.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/media/platform/mediatek/vcodec/mtk_vcodec_enc.c b/drivers/media/platform/mediatek/vcodec/mtk_vcodec_enc.c
> index 9ff439a50f53..9e8817863cb8 100644
> --- a/drivers/media/platform/mediatek/vcodec/mtk_vcodec_enc.c
> +++ b/drivers/media/platform/mediatek/vcodec/mtk_vcodec_enc.c
> @@ -821,6 +821,8 @@ static int vb2ops_venc_queue_setup(struct vb2_queue *vq,
>  		return -EINVAL;
>  
>  	if (*nplanes) {
> +		if (*nplanes != q_data->fmt->num_planes)
> +			return -EINVAL;

I don't think the claim really exists. 	For this driver, when *nplane is set,
it will be:


        case V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE:
                requested_planes = f->fmt.pix_mp.num_planes;
                if (requested_planes == 0 ||
                    requested_planes > VIDEO_MAX_PLANES)
                        return -EINVAL;
                for (i = 0; i < requested_planes; i++)
                        requested_sizes[i] =
                                f->fmt.pix_mp.plane_fmt[i].sizeimage;
                break;

Or the value the driver have set it in the previous call with *nplane == 0. So
unless there is a bug, this should not happen, and more importantly, the core
should not let that happen, meaning it should not be driver jobs to validate
this.

my 2 cents,
Nicolas


>  		for (i = 0; i < *nplanes; i++)
>  			if (sizes[i] < q_data->sizeimage[i])
>  				return -EINVAL;

Re: [PATCH v2] media: vcodec: Fix potential array out-of-bounds in encoder queue_setup

[Greg KH]

On Thu, Aug 10, 2023 at 12:12:39PM +0300, Eugen Hristev wrote:
> Hi Wei,
> 
> On 8/10/23 11:23, Wei Chen wrote:
> > variable *nplanes is provided by user via system call argument. The
> > possible value of q_data->fmt->num_planes is 1-3, while the value
> > of *nplanes can be 1-8. The array access by index i can cause array
> > out-of-bounds.
> > 
> > Fix this bug by checking *nplanes against the array size.
> > 
> > Fixes: 4e855a6efa54 ("[media] vcodec: mediatek: Add Mediatek V4L2 Video Encoder Driver")
> > Signed-off-by: Wei Chen <harperchen1110@gmail.com>
> > Cc: stable@vger.kernel.org
> > ---
> > Changes in v2:
> > - Add Fixes tag and CC stable email address
> I guess stable needs to be added by the maintainer, not by the submitter

It's easiest if it is added by the submitter, makes the maintainer's job
much easier.

thanks,

greg k-h